Question 1. Define circulation and mention the importance of circulation in living organisms.
Answer:
Circulation:
Circulation is the physiological process by which nutrients, respiratory gases, hormones, and metabolic waste matters are transported within a body through a fluid medium.
Importance of circulation:
WBBSE Life Science And Environment Class 9 Solutions
Circulation is important for living organisms as it plays the following roles:
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Question 2 Give a brief account of the different components of the human circulatory system.
Answer:
Components of the human circulatory system:
The human circulatory system is composed of three major components:
1. Circulating fluids
2. Vessels
3. A pumping organ (heart).
Circulating fluids: Blood and lymph are the circulating fluids of the human circulatory system.
WBBSE Class 9 Circulation Long Answer Questions
1. Blood: Blood is the red-colored fluid connective tissue, which carries different important materials through the blood vessels.
2. Lymph: Lymph is a special tissue fluid that flows through the lymphatic ducts, and lymph glands. It acts as another transporting medium apart from blood.
Vessels: Blood flows through three types of vessels, which form an intricate network in the human body. These are arteries, veins, and capillaries.
1. Arteries: Arteries are thick-walled vessels with roundish lumen. They carry oxygenated blood (except pulmonary arteries) from the heart to the tissues. Arteries show rhythmic pulsation.
2. Veins: Veins have thinner walls and flattish lumen. Veins carry deoxygenated blood (exception-pulmonary vein) from the tissues to the heart. They have valves to maintain the unidirectional blood flow.
3. Capillaries: These are very thin-walled blood vessels present between the arteries and the veins. These fine vessels reach deep into the tissues.
Heart: It is a muscular, four-chambered sack-like structure, which pumps blood continuously into arteries and helps blood to flow through the network of vessels in the human body.
WBBSE Life Science And Environment Class 9 Solutions
Question 3. Schematically mention different types of blood corpuscles of the human body.
Answer:
Different types of blood corpuscles or cells of the human body:
Question 4 Mention the functions of lymph, cerebrospinal fluid, and sweat.
Answer:
Functions of lymph:
The functions of lymph are as follows:
1. It supplies nutrients and oxygen deep into the tissues
2. Lymphocyte cells and antibodies present in the lymph, kill germs
3. Absorbs fat from the Intestine
4. It collects the metabolic wastes from the tissue fluid
5. Lymph maintains pressure, volume and composition of the tissue fluids.
Functions of cerebrospinal fluid:
The functions of cerebrospinal fluid are mentioned below:
1. Acts as a shock absorber for the brain & spinal cord
2. Supplies nutrition and oxygen to the brain tissue
3. Helps in the removal of metabolic wastes from the CNS.
Functions of sweat:
The functions of sweat are as mentioned below:
1. It maintains the acid-base balance, water balance and the body temperature.
2. Some salts, urea and many other materials are excreted through sweat.
Key Long Answer Questions on Human Circulatory System
Question 5. Define plasma and briefly discuss the composition of plasma.
Answer:
Plasma:
Plasma is the yellowish, slightly alkaline, transparent watery matrix of blood.
Composition of plasma:
Plasma contains water (91-92%) and solid matter (8-9% ). These solid matters include different inorganic and organic materials.
1 Inorganic matters of plasma (0.9%): Compounds of sodium, potassium, calcium, magnesium, phosphorus, iron, copper, chlorine, iodine, etc.
2 Organic matters of plasma (7-8%): Organic matters of plasma are mentioned below.
1. Sugar-glucose
2. Protein-serum albumin, serum globulin, prothrombin, fibrinogen, etc.
3. Fat-cholesterol, lecithin, phospholipids, neutral fat molecules.
4. Non-protein nitrogenous compounds-urea, uric acids, ammonia, creatinine, creatine, etc. [E] Pigments-bilirubin, biliverdin, ß-carotene etc.
5. Secreted materials-hormones, enzymes etc.
6. Gases-oxygen, carbon dioxide etc.
WBBSE Life Science And Environment Class 9 Solutions
Question 6: Mention the functions of blood plasma. How is water utilized in the human body?
Answer:
Functions of blood plasma:
The functions of blood plasma are:
1. Plasma helps in the transportation of nutrients, metabolic waste matters, hormones, etc.
2. It maintains the acid-base balance of the body.
3. Plasma proteins develop immunity and provide protection against many diseases.
4. Plasma proteins, like prothrombin and fibrinogen, help in blood clotting.
Utility of water in the human body:
Water is utilized in the human body in different ways which are as follows:
1. Water acts as the main component of the protoplasm.
2. It helps in the hydrolysis of food matters in digestion.
3. Water acts as the medium of diffusion and osmosis for nutrients, respiratory gases, metabolic wastes and hormones.
Important Long Answer Questions for Chapter 3 Life Science
Question 7 Briefly describe the role of blood in the human body.
Answer:
Functions of blood in the human body:
For human life, blood is an ultimate essentiality.
We need blood for:
Question 8. Explain the significance of blood grouping. How do you inspire somebody to blood donation?
Answer:
Significance of blood grouping:
Due to the presence of various agglutinogens and agglutinins, transfusion is not possible among all groups. If the donor’s and recipient’s blood react to cause agglutination (antigen-antibody reaction i.e., clumping of RBCs), their blood groups will be treated as mismatched or incompatible.
There will be no agglutination if the blood groups are compatible. In case of incompatible transfusion, agglutinogen of the donor’s RBC reacts with agglutinin of the recipient’s plasma to cause agglutination.
Ways to inspire somebody for blood donation:
To inspire somebody to blood donation, I shall try to eliminate his on her misconceptions regarding blood donation by saying that
1. Blood donation causes no harm to the donor.
2. The donated blood is replenished within a week.
3. Blood donation reduces the chance of heart attack and hypertension.
4. Blood can not be created artificially. So, in certain emergency situations, donated blood can save a patient’s life.
5. It is a noble gesture of a person towards society.
Practice Long Answer Questions on Circulation
Question 9 Mention the mechanism of blood coagulation in brief.
Answer:
Mechanism of blood coagulation:
The main steps of blood clotting are mentioned below:
1. Some blood platelets break near the wounds. From broken platelets enzyme Platelet- thromboplastin and from damaged tissue, tissue- thromboplastin is secreted.
2. These two enzymes, with other proteins and Ca2+prepare
3. This thrombin then reacts with another plasma protein, fibrinogen, to produce fine thread-like fibrin molecules. In this reaction also calcium ions play a supporting role. The fibrin molecules form a dense network at the opening of the wound. The blood cells get trapped in that net.
Within a few minutes, blood at that point is transformed into a thick, viscous, jelly-like mass, called thrombus. This thrombus plugs the wound and stops bleeding.
Understanding Blood Circulation for Long Answers
Question 10 Briefly describe the structure of the human heart.
Answer:
Structure of the human heart:
The human heart is a hollow, muscular, blunt-ended conical sac-like structure. It is externally covered with a bi-layered coating called pericardium. If a human heart is cut longitudinally, we can see the following anatomical features in it. Chambers of the heart: The human heart has four chambers. The upper two are called auricles or atria and the two, at the lower side, are the ventricles.
1. Auricles or atria: Auricles have comparatively thinner walls. According to the relative position, these are denoted as left and right atria. The two atria are separated by the inter-atrial septum.
2. Ventricles: These two chambers are located below the auricles. Ventricular walls are thicker and more muscular. A thick interventricular septum separates the two ventricles.
2 Valves of heart:
The left and the right atria are connected to respective ventricles with two openings, called left and right atrioventricular apertures. These two apertures are fitted with two valves. The right atrioventricular valve has three cusps (flaps), so it is called a tricuspid valve. The left one has two cusps, so it is called bicuspid valve or mitral valve.
The exits of the aorta and pulmonary trunk are fitted with two outwardly directed valves. These are known as aortic valve and pulmonary valve respectively. These are commonly called semilunar valves because of their half-moon-shaped cusps.
Concepts Related to Physiological Processes for Long Answers
Question 11 Describe the structure of the pacemaker system of the human heart.
Answer:
Structure of the pacemaker system of the human heart:
The pacemaker of the human heart is made up of a few cardiac muscle cells, specialized to generate spontaneous impulses within the heart. This impulse is spread all over the heart and makes it beat continuously in a rhythm. These tissues are called the junctional tissues or pacemakers of the heart.
The main impulse-generating center of the heart is called -the Purkinje sinoatrial node (SA node), located near the junction of the superior vena cava and right auricle. It can generate 70-80 beats/min. The next center is the atrioventricular node (AV node), positioned at the right atrioventricular wall.
It can take over the charge from an inactive SA node and can generate 60-70 beats/min. SA node and AV nodes are interconnected by three pairs of internodal connectors. From the AV node, a bundle of junctional tissues comes down through the interventricular septum.
This is called the bundle of His. This bundle is also capable of generating about 50 beats/min. This bundle then ramifies into several branches and spread in the ventricular wall as Purkinje fibers.
WBBSE Class 9 Life Science Solutions
Question 12. Briefly describe the course of circulation through the human heart.
Answer:
A course of circulation through the human heart:
The human heart beats spontaneously in a rhythmic fashion. Due to this contraction and expansion, blood is pumped through the blood vessels and circulates throughout the body. The contraction and expansion of the heart is called systole and diastole respectively. During systole and diastole, the following events occur in different chambers of the heart.
1 Diastole of auricles:
In this phase, the auricles expand, and auriculoventricular valves close. Pressure decreases in the auricles. Soon deoxygenated blood from the superior and inferior vena cava and coronary sinus enters into the right auricle. At the same time, oxygenated blood from pulmonary veins enters into the left auricle.
2 Systole of auricles:
As the auricles get completely filled, they contract. Pressure increases in the auricle. With this pressure, both tricuspid and bicuspid valves open towards the right and left ventricles respectively.
3 Diastole of ventricles:
Diastole of ventricles starts with the systole of auricles. With the opening of tricuspid and bicuspid valves deoxygenated blood enters into the right ventricle and oxygenated blood rushes into left ventricle respectively.
4 Systole of ventricles:
When the two ventricles get filled with blood, ventricular systole starts. So pressure increases inside these chambers. With this pressure tricuspid and bicuspid valves close with a jerk. With maximum ventricular pressure, the pulmonary and aortic valves open at a time.
Then deoxygenated blood from the right ventricle and oxygenated blood from the left ventricle are pumped out through the pulmonary trunk and aorta respectively. In the human heart, blood flows through two separate circuits.
The right portion of it carries deoxygenated blood and oxygenated blood flows through the left portion. In a normal human heart, the mixing of two different types of blood never happens. Therefore, the human heart acts as a perfectly double-circuit heart.
Study Guide for Class 9 Life Science Circulation Questions
Question 13 Draw a line diagram of the L.S. of the human heart to show the course of circulation through it, with labeling.
Answer:
Diagram of the human heart:
Following is a labeled diagram of the L.S. of a human heart showing the course of circulation through it.
WBBSE Class 9 Life Science Solutions
Question 14 What is meant by double circulation? Show the path of double circulation with a schematic diagram.
Answer:
Double circulation:
In higher vertebrates like birds and mammals, the heart is four-chambered. Her blood flows in two separate circuits, one through the systemic path and the other through the pulmonary path.
This type of circulation is known as double circulation. It is called a double circulatory system since it has two loops. One is from the heart to the lungs and the other is from the heart to the rest of the body.
Diagram of the path of double circulation:
The following labeled diagram shows the path of double circulation.
Question 15 Comparison among human RBC, WBC, and platelets.
Answer:
Comparison among human RBC, WBC, and platelets:
Question 16 Briefly describe the ABO system of blood grouping.
Answer:
ABO System of blood grouping:
Karl Landsteiner (1900) classified human blood into four groups depending on the presence of agglutinogen or antigen A, B, AB, O in RBC and agglutinin or antibody a, b, ab in plasma. This is known as blood grouping. The four human blood groups are A, B, AB, and O. The combinations of antigen or agglutinogen and antibody or agglutinin factors in RBC and plasma respectively in the four blood groups are shown below
Question 17 Depicts the general composition of blood through a flowchart.
Answer:
Composition of blood:
Sample Long Answer Questions from WBBSE Class 9 Life Science
Question 18. Write about the significance of blood grouping for transfusion. Represent the compatibility of different blood groups through a table.
Answer:
Significance of blood grouping for transfusion:
Transfusion of blood may be made directly from the donor’s body or from the preserved blood in the blood bank. Some precautionary measures are necessary for transfusion. These include compatibility tests (matching ABO blood groups), tests for Rh factor, etc.
If the donor’s blood does not match with that of the recipient, the RBCs are agglutinated and the patient suffers from several damages. Blood group AB has no agglutinin in plasma through its RBC contains both agglutinogen A and B. So, it can receive blood from all groups without agglutination.
This group is called ‘Universal recipient. On the other hand, blood group O has no agglutinogen in RBC through its plasma contains both agglutinin a and B. So it can donate blood to all groups without agglutination. Hence, this group is called ‘Universal donor.
Compatibility of blood groups:
Compatibility between different blood groups has been represented in the following table
Question 19 What is the Rh blood group system? State its significance.
Answer:
Rh blood group system:
The Rh blood group system is based on the Rh factor which was discovered by Landsteiner and Weiner (1940). In this system, blood is grouped on the basis of the presence or absence of a special agglutinogen or antigen called the ‘Rh factor’ in the RBC.
This antigen was first observed in Rhesus monkeys. Human blood having RBCs bearing Rh factor is called Rh positive (+) and blood without Rh factor is called Rh negative (-).
Significance:
If the blood of an Rh-positive donor is introduced into Rh negative recipient’s body then an anti-Rh factor is formed in the recipient’s blood within 12 days.
If then, the same donor’s blood is introduced into the same recipient’s body a second time, then the donor’s RBCs are agglutinated in the recipient’s body.
As a result, the recipient suffers from damage. So, it is essential to match the donor’s and recipient’s blood before transfusion.
WBBSE Class 9 Life Science Solutions
Question 20. Mention the name, position, and function/significance of different types of valves of the human heart.
Answer:
Valves of the human heart:
The main valves of the human heart are the Bicuspid or mitral, Tricuspid, Pulmonary semilunar, and Aortic semilunar valves. Other valves of the human heart are the Thebesian or Coronary and Eustachian or Caval valves.
Question 1. What is the significance of excretion?
Answer:
Significance of excretion:
Excretion is an important physiological process that helps to lead a healthy life. Its significance is discussed in the next section.
1. Maintenance of a fit and healthy life: Excretion removes all toxic and harmful matters produced in the cells by various metabolic activities.
2. Maintenance of water balance: Excretion removes excess water from the cells to maintain water balance in the body.
3. Recycling of matters: By excretion, many elements, present in the waste materials, are disposed of in nature. These are made available for reuse by the action of decomposers.
4. Economic importance: Many plant excretory products, especially alkaloids, have certain medicinal importance. Gums, resins, tannins, latex, etc. are used for industrial purposes. Some nitrogen-rich animal excretory products are used as fertilizers.
Read and Learn More Class 9 Life Science Long Answer Questions
Question 2 How do plants dispose of excretory materials?
Answer:
Excretion in plants:
Plants eliminate excretory products by the following processes:
1. Shedding of leaves: Trees, such as hog palm, Albizia, silk cotton, etc. store excretory substances in leaves. These trees shed leaves once a year to dispose of those excretory substances.
2 Exfoliation of barks: Some trees, such as guava, Arjun, etc. deposit waste matter in their bark. These plants naturally peel off their bark to eliminate those waste matters from time to time.
3 Shedding of fruits: Plants like lemon, apple, tamarind, etc. store excretory matters, like different organic acids (e.g. citric acid, tartaric acid, malic acid, etc.) or essential oils in their fruits. These are removed from these plants by shedding fruits.
4 Shedding of flowers: In some plants, excretory products are stored in their flowers. These products are excreted when different parts of the flowers are shredded.
Example: Clove flower.
5 Alkaloids: Sometimes alkaloids are stored in the stems and leaves of some plants like banyan, Calotropis, etc. In alkaloids, different types of excretory products remain solubilized. In case of injury, these alkaloids are released outside and in this way, other soluble excretory products are also released.
6 Resin secretion: In the resin ducts of the stem and leaves of some plants, like pine, a complex insoluble excretory product called resin is present.
7 Gum excretion: In some plants such as babul, soluble wastes are excreted in the form of gum.
8 Excretion of water: Potato, tomatoes, etc. solubilize different excretory products in water and then excrete them with the help of hydathodes.
WBBSE Class 9 Excretion Long Answer Questions
Question 3. Compare the different non-nitrogenous excretory products of plants.
Answer:
Non-nitrogenous excretory products of plants:
The non-nitrogenous excretory products of plants are gum, latex, and resin. Comparison among gum, latex, and resin.
Important Long Answer Questions for Chapter 3 Life Science
Question 4. Distinguish between excretion in plants and animals.
Answer:
Differences between excretion in plants and animals:
Question 5. Briefly describe the structure of the human excretory system.
Answer:
Structure of the human excretory system:
The human excretory system consists of a pair of kidneys, two ureters, a urinary bladder, and a urethra.
Kidneys:
The kidneys are brown-colored, bean-shaped structures, positioned at either side of the vertebral column, just below the ribs. The concave face of the kidney is called the pelvis.
The section of the kidney shows two distinct regions outer cortex and an inner medulla. A renal artery enters and a renal vein leaves each kidney through the pelvis.
Numerous fine tubular structures, called nephrons, are present in kidneys, which filter blood from the specially designed renal capillaries.
2 Ureter:
Ureters are two in number. Each ureter is a 35 cm long, slightly curved tube, emerging from the renal pelvis. Ureters are usually 2-4 mm in diameter.
The ureters connect kidneys to the urinary bladder, present at the lower portion of the abdominal cavity.
3 Urinary bladder and urethra:
The urinary bladder is a muscular sac, located at the front lower portion of the abdominal cavity. Urethra is a muscular tube that descends from the floor of the bladder.
The base of the urethra is equipped with sphincter muscles, which help to hold the urine inside the urinary bladder. Urine enters the urinary bladder via the ureters and leaves via the urethra. The capacity of a typical human bladder is 300-500 ml.
Practice Long Answer Questions on Excretion
Question 6. Briefly describe the structure of the nephron with a diagram.
Answer:
Structure of nephron:
A nephron has two parts-Malpighian corpuscles and renal tubule.
1 Malpighian corpuscles:
It is situated at the free and blind end of a nephron. This portion is composed of Bowman’s capsule and glomerulus. The free and blind end of the nephron forms a cup-shaped double-walled structure, called the Bowman’s capsule.
A fine branch of the renal artery enters into the Bowman’s capsule as an afferent arteriole. It ramifies to form a capillary network inside the capsule, where these capillaries reunite and return as efferent arteriole. It is comparatively narrower than the afferent arteriole. This capillary network is called the glomerulus.
2 Renal tubule:
It is a convoluted tubule, extending from the base of the Bowman’s capsule and ending in the collecting tubule. The renal tubule has three parts- the proximal convoluted tubule, which starts from the base of the Bowman’s capsule; the loop of Henle, which is a ‘U’-shaped loop-like structure, and the distal convoluted tubule, which ultimately meets a comparatively wider collecting tubule. Several collecting ducts finally unite to form thicker ducts, called the duct of Bellini.
Sample Long Answer Questions from WBBSE Class 9 Life Science
Question 7. Describe the steps of urine formation in the human kidney.
Answer:
Steps of urine formation in the human kidney:
The mechanism of urine formation in the nephron involves four different phases, which are mentioned below.
1 Glomerular ultrafiltration:
Due to increased blood pressure in the glomerular capillaries, water from blood plasma enters Bowman’s capsule. This water carries different excretory materials like urea, uric acid, etc., and many essential substances like glucose, amino acids, smaller protein molecules, salts, ions, vitamins, etc.
This process is known as glomerular ultrafiltration and the dilute fluid, collected in the Bowman’s capsule, is called glomerular filtrate.
2 Reabsorption:
Glucose and different ions (K+, Na+, etc.) are reabsorbed in cells of the renal tubule from the glomerular filtrate by active transport. Cells of proximal convoluted tubules reabsorb the small protein molecules by phagocytosis.
Ions like phosphates, bicarbonates, chlorine, etc., vitamin C, amino acids, and many other substances are reabsorbed by the renal tubule. All these reabsorbed essential materials then return to the blood.
3 Secretion: Creatine, creatinine, hippuric acid, etc. are some excretory materials, which are secreted from the renal tubule.
4 Passive absorption of water:
Excess water from the glomerular filtrate is reabsorbed by passive transport in the loop of Henle and the distal convoluted tubule. Reabsorption of water is controlled by a posterior pituitary hormone, named Antidiuretic Hormone (ADH).
After these four steps, normally concentrated urine is formed in the nephron, which is received by the collecting tubule and finally reaches the duct of Bellini.
Concepts Related to Physiological Processes for Long Answers
Question 8. Write about the roles of the accessory excretory organs other than the kidney.
Answer:
Roles of excretory organs other than kidney:
WBBSE Life Science And Environment Class 9 Solutions
Question 1 Mention the different types of plant nutrition with examples.
Answer:
Different types of plant nutrition with examples:
Plants perform nutrition in different ways, which are mentioned below:
1 Autotrophic nutrition:
In this process, plants perform nutrition by synthesising their own food from simple inorganic matter by photosynthesis followed by assimilation of the simple sugars produced in this process.
Example: All green plants, certain blue-green algae or cyanobacteria, protists like Euglena, Chrysamoeba and photosynthetic bacteria like Rhodopseudomonas, Rhodospirillum etc.
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2 Heterotrophic nutrition:
The plants which cannot carry photosynthesis due to the lack of photosynthetic pigments and depend on other living or dead or decaying organic matter for food are called heterotrophs. Their mode of nutrition is called heterotrophic heterotrophic nutrition discussed below.
1. Parasitic nutrition: In this process, some plants grow on other plants (called hosts) and draw nutrition from them.
Example: Plants like Cuscuta, Rafflesia, etc. show parasitic nutrition.
2. Saprophytic nutrition: In this process, some plants draw nutrition from dead organisms and decaying organic matter.
Example: All types of fungi, like Agaricus, Mucor, Penicillium etc. perform saprophytic nutrition.
WBBSE Class 9 Nutrition Long Answer Questions
3. Symbiotic nutrition: In some cases, two different plants live in close association and mutually benefited from that association. This mode of nutrition is called symbiotic nutrition.
Example: Lichen is a symbiotic association of algae and fungi. Here, the fungal part provides the settling platform and water to the algal part. In return, the algae synthesise and supply food.
4. Insectivory: Certain plants draw nitrogenous nutrients from small insects. These plants have special organs, typically modified for trapping insects. This mode of nutrition is called insectivory.
Example: Pitcher plant, sundew, and bladderwort are some plants which show insectivory.
2 Why animal nutrition is also called heterotrophic nutrition? Briefly describe different types of animal Nutrition.
Answer:
The reason behind animal nutrition being called heterotrophic nutrition:
Animals cannot synthesise their own food from simple inorganic materials like CO2 and water. For nutrition, they depend on other organisms.
They depend on plants or other organisms for their food. As animals depend on other organisms for food their mode of nutrition is called heterotrophic nutrition.
Different types of animal nutrition:
The following types of nutrition are found in animals:
1 Parasitic nutrition: Some animals draw nutrients from other living organisms (hosts), thereby benefiting themselves and harming the others. This mode of nutrition is called parasitic nutrition.
Example: Tapeworms, roundworms, Plasmodium etc. live inside the body of the host and are called endoparasites. Lice, ticks etc. live on the body surface of the host and are called ectoparasites.
2 Saprozoic nutrition: Some animals draw nutrients from decaying organic matter. This mode of nutrition is called saprozoic nutrition.
Example: Earthworms and Amphitrite (a marine annelid) show saprozoic nutrition.
3 Symtiotic nutrition: Sometimes, two organisms develop a close association between them, from which both are nutritionally benefited. This type of nutrition is called symbiotic nutrition.
Example: E. coli gets shelter and food in human intestine. In return, they synthesise vitamin.
4 Coprophagy: Faeces of many animals contain nutritionally important substances. Some animals draw nutrients by consuming their own faeces, or of other animals. This type of nutrition is called coprophagy.
Example: Rabbits, guinea pigs, dung beetles etc. show coprophagy.
5 Sanguinivory: Some animals draw nutrients from blood of other animals. This mode of parasitic nutrition is called sanguinivory.
Example: Auchmeromyia (blood-sucking maggot), leeches, vampire bats etc. show this type of nutrition.
Key Long Answer Questions on Human Nutrition
Question 3 Distinguish between autotrophic nutrition and heterotrophic nutrition.
Answer:
Differences between autotrophic nutrition and heterotrophic nutrition:
Question 4. Compare parasitic, saprophytic and symbiotic nutrition.
Answer:
Comparison among parasitic, saprophytic and symbiotic nutrition:
Important Long Answer Questions for Chapter 3 Life Science
Question 5 Distinguish between holophytic and holozoic nutrition.
Answer:
Differences between holophytic and holozoic nutrition:
WBBSE Life Science And Environment Class 9 Solutions
Question 6 Briefly discuss the different phases of holozoic nutrition.
Answer:
Phases of holozoic nutrition:
Holozoic nutrition involves five different phases, which are mentioned below:
1 Ingestion:
In this step, food materials are taken into the mouth, chewed by teeth and pushed into the food pipe or oesophagus. Besides teeth, the tongue also helps in this process. Salivary secretion makes the food bolus softer to facilitate this process.
2 Digestion:
This step involves the mouth, stomach, liver, pancreas and small intestine. Several enzymes are secreted inside these organs from the glandular cells. In the presence of water, these enzymes act upon respective food materials and help in the breakdown of the matter into simple and absorbable forms. This step is known as hydrolysis or digestion of food.
3 Absorption:
Mainly small intestine is involved in this process. The stomach and large intestine also play some role in it. End products of digestion are taken into the blood capillaries, where they are absorbed.
4 Assimilation:
All tissues of the body are involved in this process. In this penultimate phase of holozoic nutrition, various nutritionally important compounds and ions, absorbed in the blood from GI tract, enter into cells and become a part of the protoplasm.
5 Egestion:
This process involves the rectum and anus of the large intestine. In this last phase, undigested food matters are temporarily stored and then discharged as faeces.
Practice Long Answer Questions on Nutrition
Question 7 Briefly describe the structure of the human alimentary canal.
Answer:
Structure of the human alimentary canal:
The long tube or passage extending from mouth to anus through which food passes during digestion is called the alimentary canal.
It is composed of the following parts:
1 Mouth:
It is the opening of the alimentary canal, guarded by a pair of lips. The inner chamber is known as the buccal cavity, which consists of a muscular tongue at the base. The cavity also consists of an upper and a lower jaw, fitted with a maximum of 32 teeth (16 on each jaw).
2 Pharynx: It is a slightly swollen, muscular chamber behind the buccal cavity.
3 Oesophagus: It is a straight, vertical, muscular tube, that carries food from the pharynx to the stomach.
4 Stomach:
It is a J-shaped muscular sac, present on the left side of the upper abdominal cavity. It consists of four regions-the cardiac stomach (upper portion, close to the heart), fundic stomach (wide middle portion), the body (portion between fundic stomach and pyloric stomach) and the pyloric stomach (lower portion, attached to the duodenum).
5 Small intestine:
It is a very long, narrow and highly convoluted tube, that extends from the stomach to the large intestine and occupies a maximum portion of the abdominal cavity. It has three portions-duodenum (emerging from the stomach), jejunum (the middle region) and ileum (meets the large intestine).
6 Large intestine:
This tube is less coiled and broader than the small intestine. It consists of three parts- caecum (the dilated portion, where the small intestine meets), colon (the tubular part consisting of four regions-ascending colons, transverse colon, descending colon and sigmoid colon), rectum (a wide tube, next to the sigmoid colon, that proceeds downward and opens through the anus).
WBBSE Life Science And Environment Class 9 Solutions
Question 8. State the differences between small and large intestines. Distinguish between the stomach and small intestine.
Answer:
Differences between small and large intestines:
Differences between the stomach and small intestine:
Understanding Nutritional Components for Long Answers
Question 9 Briefly describe the name, location and secretary substance of different digestive glands of the human alimentary system.
Answer:
Different digestive glands of the human alimentary system:
The human alimentary system consists of different types of digestive glands.
These are discussed below:
WBBSE Life Science And Environment Class 9 Solutions
Question 10. Mention the names, sources and roles of the different amylolytic enzymes in digestion.
Different amylolytic enzymes in digestion:
The names, sources and roles of different amylolytic enzymes that take part in digestion are given below:
Question 11. Mention the names, sources and roles of different proteolytic and lipolytic enzymes in digestion.
Different proteolytic enzymes in digestion:
The names, sources and roles of different proteolytic enzymes are given below:
Different lipolytic enzymes in digestion:
The names, sources and roles of different lipolytic enzymes are given below:
WBBSE Class 9 Life Science Solutions
Question 12 How does absorption of digested food matter occur in the human GI tract? Briefly explain the method of assimilation of nutrients in the human body.
Answer:
Method of absorption of food:
Absorption mainly occurs in the small intestine. The inner wall of the intestine develops many small finger-like projections called villi (singular-villus).
Each villus has a central lymph duct called lacteal, and a few blood capillaries. Monosaccharides, amino acids and glycerol are absorbed in the blood capillaries. Fatty acids are taken into the lacteals.
Besides the small intestine, a few materials are absorbed through the epithelial lining of the stomach and large intestine. These include water, alcohol, few salts and drugs.
Method of assimilation of food:
From the intestine, blood carries glucose, fructose, amino acids and a few fatty acid molecules to the liver, through hepatic portal vessels. After supplying nutrients in the liver, this blood moves to the systemic circulation.
Lymph ducts carry simple fat molecules and finally transfer them to the systemic circulation. As a result, all nutrients reach every tissue and cell through blood. Finally, these essential molecules are incorporated into the protoplasm of the cells.
Question 13 Briefly explain the fate of the nutrients in a living cell. Mention the features of a balanced diet.
Answer:
The Fate of Nutrients in a living cell:
The absorbed nutrients get assimilated within the cells and carry out different functions. Monosaccharides participate in cellular respiration as respiratory substrates.
These are oxidised to generate energy, which is necessary for different life activities. Proteins help in building body cells and lipids are kept as stored matter.
Vitamins act as coenzymes and minerals act as cofactors of various enzymes, or as fundamental components of some cellular molecules. Almost all end products of digestion undergo necessary changes within the cells through the process of metabolism.
Features of a balanced diet:
Foods, that we take every day, do not always make a balanced diet. Moreover, any single food material cannot be treated as a balanced diet.
It should have certain features which are as follows:
1. It should help to maintain the growth and perfect shape of the body.
2. It should perfectly meet the calorific demand of a body.
3. It should help to develop resistance against infection.
WBBSE Class 9 Life Science Solutions
Question 14 What do you understand by the term mechanical digestion? Mention the different types of mechanical digestion.
Answer:
Mechanical digestion:
The process by which dry and semi-solid foods are converted into smaller fragments in the GI tract and also the process by which the food is pushed forward along the G1 tract is called mechanical digestion.
Different types of mechanical digestion:
Generally, mechanical digestion is of three types:
1 Mastication or chewing: Food matters taken into the buccal cavity undergo mechanical processing. Different types of teeth help to cut, tear and masticate the food matter into small particles. Saliva moistens it to form a soft and smooth dough-like matter. This whole process is known as mastication or chewing of food.
2 Swallowing: The process by which the food passes from the mouth to the pharynx and then enters the oesophagus by shutting the epiglottis, is known as swallowing or deglutition.
3 Movements of the GI tract: Movements of the gastrointestinal tract occur, which help in the forward movement of food. Generally, two types of movements are seen-peristalsis and segmentation movement.
Question 15 Describe the different phases of protein digestion with the help of a suitable schematic diagram.
Answer:
Different phases of protein digestion:
Digestion of protein occurs stepwise, mostly in the stomach and small intestine. Several proteolytic enzymes (enzymes that break down protein) influence the process of protein digestion.
The different phases of protein digestion are as follows:
1 Digestion in the buccal cavity: Since no proteolytic enzyme is present in the buccal cavity, protein digestion does not occur here.
2 Digestion in the stomach:
This is the site where protein digestion starts. Upon entering the stomach, the food is converted into chyle after it gets mixed with the gastric juice secreted from the gastric glands of the stomach.
The presence of HCl in the gastric juice makes the chyle acidic and activates the proteolytic enzyme pepsin. Pepsin converts proteins into peptones. However, pepsin is unable to execute the complete digestion of proteins into peptones and therefore, incomplete digestion of proteins occur in the stomach.
3 Digestion in the small intestine:
Upon entering the small intestine, the undigested proteins and peptones mix with the pancreatic and the enteric juices. Proteolytic enzymes, named trypsin and chymotrypsin present the pancreatic juice hydrolyse peptones and undigested proteins into small peptides.
After that, these small peptides are broken down into amino acids by the action of another enzyme, called erepsin, which is present in the enteric juice. These amino acids are then absorbed into the blood with the help of villi present in the small intestine.
WBBSE Class 9 Life Science Solutions
Question 16. Explain the different steps of carbohydrate digestion with the help of a suitable schematic diagram.
Answer:
Different steps of carbohydrate digestion:
Carbohydrate digestion occurs mainly in the buccal cavity and in the small intestine.
1 Digestion in the buccal cavity:
Carbohydrates especially boiled starch’ present in the food, mix with Ptyaline present in the salivary juice and is converted to maltose and isomaltose. Maltase present in saliva converts maltose into 2 molecules of glucose.
The quantity of maltase in the saliva is very low and therefore, small amounts of glucose are formed in the buccal cavity by the action of the salivary enzymes.
2 Digestion in the stomach:
Digestion of carbohydrates does not occur in the stomach due to the absence of amylolytic or carbohydrate-digesting enzymes. Only a small amount of sucrose is hydrolysed into glucose and fructose with the help of HCI.
3 Digestion in the small intestine:
In the small intestine, both boiled and unboiled starch gets converted into maltose by the action of pancreatic amylase. Maltase present in enteric juice then breaks down maltose into 2 molecules of glucose. The majority of the ingested starch is broken down by pancreatic amylase.
But if any portion of the starch is still left unbroken, then intestinal amylase will act on it to break it down into simpler components. Moreover, intestinal lactase and sucrase hydrolyse lactose into glucose and galactose and sucrose into glucose and fructose respectively.
In this way, complex carbohydrates are broken down into simple monosaccharide units which are then absorbed in the body.
Concepts Related to Physiological Processes for Long Answers
Question 17 What do you mean by fat digestion? Briefly describe the different steps involved in fat digestion.
Answer:
Fat digestion:
The process by which fats or lipids are broken down into fatty acids and glycerol in the alimentary canal with help of the enzyme lipase and bile salts present in the digestive juice is called fat digestion.
Different steps of fat digestion:
Fat digestion mainly occurs in the stomach and in the small intestine. The different steps of fat digestion are described below.
1 Digestion in the buccal cavity: Fat digestion does not occur in the buccal cavity due to insufficient amount of fat digestive enzymes.
2 Digestion in the stomach:
When the ingested food enters the stomach, it gets mixed with the gastric juice. Gastric lipase, present in the gastric juice, breaks down fats into fatty acids and glycerol.
Digestion in the small intestine: As the lipid molecules enter the duodenum of the small intestine, they get mixed with the bile, pancreatic and intestinal juices. The bile salts present in the bile juice emulsify the lipid molecules.
Then pancreatic and intestinal lipases act on the emulsified fats and break them into fatty acids and glycerol. In this way, fat is broken down into fatty acids and glycerol which are then absorbed in the bloodstream.
WBBSE Class 9 Life Science Solutions
Question 18 What is basal metabolic rate? Mention the factors that regulate basal metabolic rate.
Answer:
Basal Metabolic Rate (BMR):
Basal metabolic rate is the amount of energy given out per hour and per square metre of body surface area of a person who is awake, but at complete mental and physical rest in a comfortable environment and in a post-absorptive state, i.e. 12 to 18 hours after a meal.
It is the minimum amount of energy required to maintain vital physiological functions such as breathing, blood circulation etc. The BMR of a healthy adult man is 40 kcal/hour/sq. metre body surface area and the BMR of a healthy adult female is 37 kcal/hour/sq. metre body surface area. It is generally measured with the help of Benedict Roth’s apparatus.
Factors regulating basal metabolic rate:
The factors which regulate the basal metabolic rate are discussed below:
1 Body surface area: BMR is directly proportional to the body surface area.
2 Age: Children have greater body surface area as compared to their body weight, therefore, in children, BMR is more than in adults.
3 Sex: Males have greater BMR than females.
4 Nutritional status: Long-term malnutrition causes a decrease in BMR.
5 Weather: People living in temperate regions have greater BMR than people living in warmer areas.
Benedict Roth apparatus
6 Endocrine glands: Hormones secreted from the thyroid, adrenal glands and anterior pituitary, increase BMR.
7 Body temperature: BMR increases or decreases with an increase or decrease in body temperature.
Study Guide for Class 9 Life Science Nutrition Questions
Question 19. State the significance of metabolism. What do you mean by metabolic disorders and state the reasons for metabolic problems in humans?
Significance of metabolism:
The significance of metabolism is as follows:
1 Maintenance of body homeostasis: Metabolism is essential for the normal functioning of all biochemical reactions taking place in the body.
2 Generation of energy: Metabolism provides energy, which is needed for the normal functioning of various body processes.
Metabolic disorders/problems:
The condition in which normal body metabolism is altered, is called metabolic disorders or problems. Generally, metabolism decreases or sometimes halts in such conditions.
Reasons for metabolic disorders in humans:
The reasons for metabolic disorders in humans are as follows:
1. Insufficient enzymes: A decrease in functional enzymes is one of the main reasons of metabolic problems.
2 Insufficient hormones: Hormones generally regulate several metabolic processes. In the absence of such hormones, these metabolic processes are altered leading to metabolic problems.
3 Genetic problems: Generally mutations of genes, involved in different metabolic pathways, lead to metabolic disorders.
WBBSE Class 9 Life Science Solutions
Question 20. Mention the role of the small intestine in the digestion of food. OR, Describe the digestion of food in the small intestine with the help of a suitable schematic diagram.
Answer:
Digestion in the small intestine:
Question 21. Mention the determining factors of a balanced diet. List a balance diet chart of an adult person of your own choice.
Factors of a balanced diet:
The determining factors of a balanced diet in humans are:
1. Sex
2. Age
3. Metabolism
4. Physical activity
5. Growth and pregnancy
6. Body weight
7. Weight and size
8. Genetics
9. Hormone levels
10. Any illness
Diet chart for a healthy person:
A healthy diet chart for adults:
WBBSE Class 9 Life Science Question And Answer
Question 22. Mention the name, symptoms and causes of some metabolic diseases in the human body.
Answer:
Name, symptoms and causes of some metabolic diseases:
Sample Long Answer Questions from WBBSE Class 9 Life Science
Question 23. Draw a labelled diagram of the human alimentary system.
Answer:
A labelled diagram of the human alimentary system:
WBBSE Life Science And Environment Class 9 Solutions
Question 1. Mention the source and role of the basic raw materials of photosynthesis.
Answer:
Source and role of basic raw materials of photosynthesis:
WBBSE Class 9 Photosynthesis Long Answer Questions
Question 2. Write the role of chlorophyll in photosynthesis. How is photosynthesis related to the flow of energy in the environment?
Answer:
Role of chlorophyll in photosynthesis:
Chlorophyll gets excited by the absorption of photon particles of sunlight and dissociates the water absorbed by the root hairs into H+ and OH– ions. Chlorophyll also converts solar energy into chemical energy which is stored within ATP in the form of potential energy.
Read and Learn More Class 9 Life Science Long Answer Questions
Relation of photosynthesis with energy flow in the environment:
Key Long Answer Questions on Photosynthesis
WBBSE Life Science And Environment Class 9 Solutions
Question 3 Mention the name, location, and functions of the main pigments for photosynthesis.
Answer:
Name, location, and function of main photosynthetic pigments:
Important Long Answer Questions for Chapter 3 Life Science
Question 4. Write the differences between absorption and action spectra. Why leaf is the ideal place for photosynthesis?
Answer:
Difference between the absorption spectrum and the action spectrum
Leaf-the ideal place for photosynthesis:
WBBSE Life Science And Environment Class 9 Solutions
Question 5 Briefly explain the chemical reaction of photosynthesis. Differentiate between primary photosynthetic pigments and accessory photosynthetic pigments.
Answer:
The chemical reaction of photosynthesis:
The equation of the chemical reaction of photosynthesis can be summarised as follows:
\(\underset{\text { carbon dioxide }}{6 \mathrm{CO}_2}+\underset{\text { Water }}{12 \mathrm{H}_2 \mathrm{O}} \underset{\text { Sunlight }}{\stackrel{\text { Chlorophyll }}{\longrightarrow}} \underset{6}{\mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6}+\underset{\text { Oxygen }}{6 \mathrm{O}_2 \uparrow}+6 \mathrm{H}_2 \mathrm{O}\)
This equation can be explained as:
1. 6 carbon dioxide molecules and 12 water molecules react to produce one glucose molecule 6 molecules of oxygen and 6 molecules of water.
2. The reaction requires energy in the form of light (mainly sunlight) and occurs in the presence of the biocatalyst, a green pigment called chlorophyll.
3. Carbon dioxide and water combine through a number of chains. reactions to synthesize glucose.
4. Oxygen is evolved as a byproduct in this process.
Differences between primary photosynthetic pigments and accessory photosynthetic pigments:
Practice Long Answer Questions on Photosynthesis
6 Briefly describe the reactions of the light-dependent phase of photosynthesis.
Answer:
Reactions of the light-dependent phase of photosynthesis:
The reactions of the light-dependent phase of photosynthesis occur in the grana of chloroplastids. ATP, NADPH2, H2O, and O2, are the end products of this light-dependent phase of photosynthesis.
Five different reactions occur in this phase, which are mentioned below:
1. Activation of chlorophyll:
Solar energy reaches the earth in the form of energy-packed particles, called photons. When these photon particles hit the chlorophyll molecules present in the chloroplast of mesophyll tissue, they get excited and release energized electrons. This event is known as the activation of chlorophyll.
2. Photolysis of water:
Activated chlorophyll dissociates water molecules into hydrogen ions or protons (H+) and hydroxyl ions (OH–). This light-dependent dissociation of the water molecules is called photolysis or ionization of water.
3. Reduction of NADP+:
NADP is a proton acceptor, present in the chloroplasts. Proton (H+) produced during the photolysis of water, reacts with NADP+ and reduces it to produce NADPH + H+. In this reaction, necessary electrons for the subsequent reactions are emitted from the excited chlorophylls.
4. Production of oxygen:
Hydroxyl ions (OH¯), produced during the dissociation or photolysis of water, release electrons and are transformed into hydroxyl radicals [OH]. These radicals combine to form water (H2O) and oxygen (O2) molecules.
5 Photosynthetic phosphorylation: The energized electrons, released from the photon-hit chlorophylls, help to combine adenosine diphosphate (ADP) and inorganic phosphate (IP) to produce an energy-rich compound, called adenosine triphosphate (ATP). This reaction is known as photosynthetic phosphorylation or photophosphorylation.
∴ \(\mathrm{ADP}+\mathrm{Pi} \longrightarrow \text { ATP }\)
Concepts Related to Photosynthesis for Long Answers
Question 7. Briefly describe the steps of the light-independent phase of photosynthesis along with a diagram.
Answer:
The steps of the light-independent phase of photosynthesis:
The reactions of the light-independent phase occur in the stroma of chloroplastids. The end product of this phase is glucose (carbohydrate) and RuBP is synthesized. Four different reactions occur in this phase of photosynthesis. These are described in the following matter.
1. Carbon assimilation:
Photosynthetic plants absorb CO2, from the atmosphere. This CO2 reacts with RuBP in the stroma of chloroplast to produce phosphoglyceric acid (PGA). The enzyme RuBis CO2 catalyzes this reaction. In this reaction, the carbon atom (C) of CO2 is assimilated within the cellular organic compounds. This reaction is known as carbon assimilation.
2 Reduction of PGA:
In this step, two products of the light-dependent phase, namely NADPH + H+ and ATP come into action. NADPH + H+ reacts with phosphoglyceric acid and reduces it to produce phosphoglyceraldehyde (PGAld). ATP supplies the necessary chemical energy for this reaction.
∴ \(12 \mathrm{PGA}+12\left(\mathrm{NADP}+\mathrm{H}^{+}\right)+12 \mathrm{ATP} \longrightarrow 12 \mathrm{PGAId}+12 \mathrm{NADP}++12 \mathrm{ADP}+12 \mathrm{Pi}\)
3 Resynthesis of RuBP:
Out of the total PGAld produced, 5/6th part undergoes a cycle of reactions and resynthesizes RuBP. This reaction of resynthesis of RuBP occurs in a cyclic manner. This reaction cycle is named the Calvin cycle.
As scientist Melvin Calvin first traced this cycle, this cycle is named the Calvin cycle. In this cycle, several intermediate compounds are produced in subsequent steps.
4 Glucose synthesis:
Out of the total PGAld produced, 1/6th part takes part in the synthesis of glucose. Within the stroma of chloroplasts, PGAld molecules undergo a series of reactions to synthesize glucose.
2\(\text { PGAId } \longrightarrow \mathrm{C}_6 \mathrm{H}_{12} \mathrm{O}_6 \text { (Glucose) }\)
WBBSE Life Science And Environment Class 9 Solutions
Question 8 Write the significance of the light-dependent phase of photosynthesis. What is the significance of the light-independent phase of photosynthesis?
Answer:
Significance of the light-dependent phase of photosynthesis:
1. During photophosphorylation of the light-dependent phase, solar energy is converted into chemical energy and is stored as ATP.
2. ATP, produced during photophosphorylation, and NADPH+H+, produced during the reduction of NADP+, in the light-dependent phase, help in the reduction of PGA to PGAld, later in the light-independent phase.
3. During the Hill reaction, water gets dissociated to liberate oxygen. This oxygen helps in the respiration of all living organisms as well as in combustion.
Significance of light-independent phase of photosynthesis:
1. Solar energy gets stored in glucose as potential energy. This energy helps the living world, directly or indirectly, to perform all metabolic activities.
2. The CO2 released into the environment by all organisms during respiration, is taken up by plants during the light-independent phase. As a result, the balance of CO2 and O2 is maintained in the environment.
3. During this phase, the assimilation of carbon takes place, and carbohydrates, in the form of glucose, is produced as an end product. This glucose, either directly or indirectly, is the source of food for all heterotrophic living organisms.
Sample Long Answer Questions from WBBSE Class 9 Life Science
Question 9 What is the significance of photosynthesis?
Answer:
Significance of photosynthesis:
1. Trapping and transformation of solar energy:
Solar energy from the sun is trapped by chlorophyll and transformed into chemical potential energy in the glucose molecule. This energy is then passed on from the producers (plants) to the consumers through the food chain and is liberated during respiration.
2 Source of food:
Through the process of photosynthesis, inorganic materials like water and CO2 combine to produce organic molecule glucose, which is the basic component of all food matters on earth. Not only plants, but other animals also obtain this food, either directly or indirectly, to survive.
3 Maintainance of O2 and CO2 balance in the environment:
During respiration, all living organisms release CO2 and absorb O2. On the other hand, green plants release O, and
4 Source of fuel:
Due to natural disasters, like earthquakes, plants get trapped under the soil and in due course of time get converted into coal and mineral oils. The energy obtained from these coal and mineral oils originally is solar energy which was entrapped by the plants in the past. This is how photosynthesis is the only source of different types of fuel.
5 Sources of human welfare:
We get different types of important materials from plants, like food, wood, paper, cloth, rubber, gum, paint, etc. Apart from these, we get different alkaloids like morphine, quinine, reserpine, etc., and various medicines from plants. Therefore, plants, more specifically photosynthesis, is very important physiological process for human welfare.
Question 1 What are inhalation and exhalation? Briefly describe the salient features of the respiratory organs of animals.
Answer:
Inhalation: The mechanical process, by which organisms take in air from the environment, is called inhalation.
Exhalation: The mechanical process, by which living organisms give out carbon dioxide-rich air from their respiratory organs, into the environment, is called exhalation.
Salient features of the respiratory organs of animals:
1 Moistness: The moist cell membrane of unicellular organisms and the moist skin of earthworms, leeches, frogs, and toads act as respiratory organs. Atmospheric oxygen enters into the blood vessels through these moist skin, by diffusion.
2 Surface area: A respiratory organ should have a large surface area because surface area improves its efficiency by transporting or exchanging enough oxygen. The thin and numerous lamellae of gills and densely packed alveoli of lungs make these two organs best suited for aquatic and aerial respiration respectively.
Read and Learn More Class 9 Life Science Long Answer Questions
3 Vascularity: A respiratory organ should be well vascularised. This helps in the better exchange of respiratory gases. The rich distribution of blood capillaries in the gills and lungs makes these respiratory organs highly efficient for gaseous exchange.
WBBSE Class 9 Respiration Long Answer Questions
Question 2 Explain the role of different parts of the plant body in gaseous exchange.
Answer:
Role of different parts of plant body in gaseous exchange:
Plants do not have typical respiratory organs like animals. Few sites on a plant body help in the exchange of O2 and CO2. These are stomata, lenticels, pneumatophores, etc.
1 Stomata: Stomata are the tiny pores, present on the surface of leaves, tender stems, and other parts of the plant body that help in the exchange of gases. These are the special intracellular spaces bordered by two specialized bean-shaped parenchyma cells, called guard cells, which open and close. Thus, allowing the exchange of gases.
2 Lenticels: Lenticels are lens-shaped spaces, formed in the cracks on the bark of trees. These function as pores, providing the pathway for the direct exchange of gases between the internal tissues and atmosphere through the bark, which is otherwise impermeable to gases.
3 Pneumatophores: Halophytes (mainly mangrove trees) grow on saline muddy soil in the delta region of rivers. This soil has poor oxygen content. To counter it, some roots of these plants grow vertically upward against gravity and come above the soil.
These roots are highly porous. These are called pneumatophores or breathing roots, which help in the exchange of gases directly from the air.
WBBSE Life Science And Environment Class 9 Solutions
Question 3 How do insects perform organ-level respiration with the help of the trachea?
Answer:
Tracheal respiration in insects:
In insects (such as cockroaches), a network of very thin-walled tubes is spread in the body. These tubes are known as trachea. Air enters the tracheal system through tiny paired pores present on pleurites along the two sides of the body.
These pores are called spiracles. Trachea ramifies or forms branches inside the body cavity, longitudinally and transversely to form a tracheal network. The finest ends of tracheal branches are called tracheoles.
Each tracheole ends in a large tracheal end cell, which gives off some fine cytoplasmic processes. These processes enter into intercellular tissue fluid.
Gaseous exchange occurs between the tracheal end cells and tissue fluid and finally from tissue fluid to the cells by the process of diffusion.
Key Long Answer Questions on Human Respiration
Question 4 Briefly describe the main respiratory organ of fishes. How do fishes perform aquatic respiration?
Answer:
Structure of respiratory organs of fishes:
Gills perform the respiratory function in fish. In the case of cartilaginous fishes, these are present in gill clefts, and in bony fishes, these are held in gill chambers at two sides of the head, covered with a bony plate, called the operculum. A gill has a curved bony skeletal structure, called a gill arch.
Two rows of thin and flat gill filaments are densely arranged in a parallel manner along the gill arch like teeth of a comb. Numerous, very thin membranous folds emerge from either side of a gill filament, called gill lamellae. Gill filaments and lamellae are supplied with a dense network of blood capillaries.
Mechanism of aquatic respiration in fishes:
Fishes continuously open and close their mouth. When they open their mouth, freshwater flows into the buccal cavity. They open the opercula to allow water to pass through the gills to flood the gill filaments before leaving the two gill chambers.
As the water passes through the gills, O2 diffuses into the blood capillaries and CO2 diffuses out in the water. This is how fishes perform aquatic respiration.
Important Long Answer Questions for Chapter 3 Life Science
Question 5 Describe the structure of the human lung. Mention its function. Structure of the human lung
Answer:
Lungs are paired, sac-like structures located in the thoracic cavity of the human body, well protected by the rib cage. Lungs remain separated from the abdominal cavity by a muscular sheet or membrane, called the diaphragm.
Each lung is covered with a double-layered covering called pleura. The outer layer is called the parietal and the inner one is called the visceral pleura. A fluid-filled space is present between these two layers.
The left lung is slightly smaller with two lobes to accommodate the heart and the right one is larger with three lobes. A long, thin-walled, tubular wind-pipe or trachea goes down vertically along the medial chest line and divides into two bronchi (singular-bronchus) before entering the lungs.
Each bronchus then ramifies several times, from finer to finest air tubules, called bronchioles. Finally, each of the bronchioles ends into a tiny balloon-shaped alveolus (plural- alveoli). Thus, countless alveoli form a lung.
Two human lungs are composed of 30 to 50 crore of alveoli. The wall of each alveolus is rich in blood capillaries. That is why healthy lungs appear reddish pink.
Function:
1. Lungs are the chief respiratory organs in man. It helps in respiration.
2. In the lungs O2 enters from the alveolar air into the blood capillaries and CO2 comes out from the blood capillaries into the alveolar air.
Practice Long Answer Questions on Respiration
Question 6 Describe the breathing mechanism of man.
Answer:
Mechanism of human breathing:
The organ-level respiration or breathing in man involves two phases:
1. Inspiration
2. Expiration.
1 Inspiration:
1. As we breathe in, diaphragm muscles contract and move down toward the abdominal cavity.
2. Intercostal (present in between ribs) muscles contract to pull the ribs upward to some Diaphragm comes down extent.
3. By these two actions, the space inside the ribcage increases. This reduces the pressure inside the chest cavity and in the pleural fluid.
4. In this situation, thoracic pressure reaches below atmospheric pressure. As a result, oxygen-rich air from the atmosphere rushes into the body through the nostrils, nasal passage, glottis, larynx, trachea, bronchus, and bronchioles to reach the alveoli.
Gaseous exchange occurs between alveolar air and capillary blood. After this exchange, the air inside the lungs becomes rich in carbon dioxide (CO2). After this, the brain sends a signal for expiration.
2 Expiration:
1. The diaphragm expands and moves towards the chest cavity.
2. Intercostal muscles relax and the ribs go down to their normal position.
3. Due to the above two actions, the internal volume of the chest cavity reduces. As a result, pressure increases in the pleural fluid, as well as in the lungs.
4. The lungs contract and the CO2-rich air, inside the lung, is pushed out along the reverse path.
Concepts Related to Physiological Processes for Long Answers
Question 7 How do the lungs get weak and diseased? How can the lungs be kept fit?
Answer:
Reason for weak and diseased lungs:
Lungs are very important organs in our body, which are involved in respiration. If the lungs do not perform their function perfectly, we will fall sick. Lungs lose their efficiency due to aging, obesity, infections, and in most cases smoking.
A dark-colored tar is deposited in the lungs of smokers, which contains several potential carcinogens (cancer-inducing substances), leading to lung cancer. Smokers develop a chronic lung disease, called emphysema. In this case, gaseous exchange reduces and the efficiency of the lungs declines permanently.
Passive smokers (who unconsciously inhale the smoke released by active smokers) are the worst victims of this bad habit and also suffer from the same diseases. Due to allergic effects, a person may suffer from asthma and COPD (Chronic Obstructive Pulmonary Disease).
Infection with Mycobacterium tuberculosis may lead to a serious lung disease, called tuberculosis, whose symptoms are coughing (sometimes with sputum with blood), chest pain, weakness, weight loss, fever, etc
Methods of keeping the lungs fit:
Breathing exercise or ‘pranayam’ keeps our lungs healthy. The basis of this exercise is steady, forceful, and rhythmic inspiration and expiration. It increases the extensibility of the lungs and thus, increases the oxygen intake capacity of the body.
But, pranayam should be practiced under the proper guidance of a competent yoga teacher. Moreover, swimming, cycling, jogging and even walking keep our lungs healthy.
Study Guide for Class 9 Life Science Respiration Questions
Question 8. Write about the accessory respiratory organs with examples. Mention its necessity in animals. 3+2
Answer:
Accessory respiratory organs:
In some bony fishes, living in muddy water where oxygen supply is scanty, respiration by gills is supplemented by a special organ called the accessory breathing organ. e.g. Koi (Anabas), Magur (Clarias), Singhi (Heteropneustes).
The name of the accessory respiratory organ of Magur is called the arborescent organ; for Singhi it’s a tubular air sac and for Koi, it’s a labyrinthine organ.
Necessity in animals:
1. These fishes are unable to live submerged in water and are allowed to grasp air through mouth by lifting their head above water when oxygen concentration is very low in the water. Absorption of oxygen appears to be the primary function of the accessory respiratory organ.
2. Some fishes have the natural instinct to make short excursions to the land from their primal aquatic homes.
Sample Long Answer Questions from WBBSE Class 9 Life Science
Question 9 What is meant by active and passive smoking? Write the poisonous effect of smoking.
Answer:
Active smoking: Active smoking is the intentional inhalation of tobacco smoke by a smoker. Smokers puff directly from cigarettes.
Passive smoking: Passive smoking is the involuntary inhalation of smoke from tobacco products. Such smoke is called Secondhand Smoke (SHS) or Environmental Tobacco Smoke (ETS).
The poisonous effect of smoking:
1. Emphysema means excess air in the lungs, caused by many years of smoking, resulting in chronic infection, obstruction of airways makes expiration difficult, bronchiolar obstruction increases, etc.,
2. Lung cancer or carcinoma occurs due to many carcinogenic agents present in tobacco smoke,
3. Chronic obstructive pulmonary disease (COPD)
4. Heart disease, stroke
5. Eye diseases
6. Increases the risk of tuberculosis,
7. Problems of the immune system including rheumatoid arthritis.
Question 1 Give a brief account of different microbial bio-control agents.
Answer:
Different microbial bio-control agents:
Different bacteria, viruses, fungi, and protozoa can be used as bio-control agents.
1 Bacteria as a bio-control agent:
Bacillus thuringiensis produces a poison, called Bt toxin, which is used to control the growth of larvae of moths, beetles and flies. Scientists have introduced genetic materials of these bacteria in corn, vegetables and cotton plants.
As a result, Bt-toxin is synthesized in these plants, so that insect parasites cannot attack them. Pseudomonas fluorescence has been commercially used as a fungicide. Bacillus papillae is used to control the Japanese beetle, a pest of maple and rose plants.
2 Virus as a bio-control agent:
1. Caudovirales is a group of phage viruses, which kill Salmonella (bacteria) from water bodies. This phage virus can be used to eliminate Salmonella from drinking water to protect us from severe diarrhea.
2. Nuclear Polyhedrosis Virus (NPV) or Cytoplasmic Polyhedrosis Virus (CPV) can kill larvae of moths and butterflies. These viruses are used to destroy some harmful insects like pine sawflies, gypsy moths, tussock moths, etc.
Read and Learn More Class 9 Life Science Long Answer Questions
3 Protozoa as a bio-control agent:
1. Nosema locustae is a protozoan microbe, which is used to control some insect pests.
2. Mattesia grandis, another protozoan, effectively controls cotton ball weevils.
WBBSE Class 9 Microbes in Human Welfare Long Answer Questions
4 Fungus as a bio-control agent:
Beauveria bassiana is a fungus, which can control mosquito populations effectively. It can be used in those areas, where mosquitoes have developed resistance against chemical insecticides. It can also control termites, whiteflies, and many other insects.
WBBSE Life Science And Environment Class 9 Solutions
Question 2. What is meant by biofertiliser? Mention the roles of bacteria as biofertilisers.
Answer:
Biofertilizer:
Certain microorganisms have the ability to promote plant growth by increasing the supply or availability of primary nutrients to plants. These are applied in crop fields to increase soil fertility. These are known as biofertilizers.
Roles of different bacteria as biofertilizers:
1. Rhizobium leguminosarum is a symbiotic bacteria present in the root nodules of leguminous plants. These bacteria trap atmospheric nitrogen and convert it into nitrates. Ultimately this nitrate is transferred to the plant body as an essential nutrient.
2. Frankia is another symbiotic bacteria, which dwells in the root nodules of plants like Casuarina, Rubus, Alnus, etc.
3. Some soil-living, aerobic bacteria can absorb atmospheric nitrogen into the cells. After death, this nitrogen is released in soil as nitrates and increases its fertility. Azotobacter sp., Azomonas sp., Derxia sp., Azospirillum sp., etc., are some examples.
4. Among the anaerobic nitrogen-fixing bacteria Clostridium sp., Chromatium sp., and Chlorobium sp. are mentionable.
5. Some bacteria like Thiobacillus, Micrococcus, and Acrobacter are capable of solubilizing inorganic phosphorus from insoluble compounds in the soil. The use of these bacteria as biofertilizers enhance the phosphate nutrition of plants.
Important Long Answer Questions for Chapter 4 Life Science
Question 3. What do you mean by nitrogen fixation? Mention the roles of cyanobacteria as biofertilizers.
Answer:
Nitrogen fixation:
Nitrogen fixation is a process in which nitrogen (N2) in the atmosphere is converted into ammonia (NH3). The nitrogen fixation process occurs naturally in the soil by nitrogen-fixing bacteria.
Roles of cyanobacteria as biofertilizers:
Some cyanobacteria can trap atmospheric nitrogen. These include Anabaena sp., Nostoc sp., Aulosira sp., Stigonema sp., Plectonema sp., etc. These are now cultured in the water of paddy fields. When these organisms die and decompose, nitrates get absorbed in the soil and increase its fertility.
Recently Azolla is being cultivated in the irrigated paddy fields. Azolla is an aquatic fern. Nitrogen-fixing cyanobacteria Anabaena azollae live in the leaves of this fern. These cyanobacteria fix nitrogen from the atmosphere and supply it to Azolla.
Azolla die and get decomposed in the soil. Through this process, soil get nitrogen from the decomposed body of this fern. In Southeast Asian countries, the cultivation of Azolla in paddy fields is a regular practice now.
It has reduced the need for chemical fertilizers and has cut down the cost of paddy cultivation. Besides this, cyanobacteria secrete ascorbic acid, Vit. B and auxin in the soil.
WBBSE Life Science And Environment Class 9 Solutions
Question 4. Mention the roles of mycorrhiza as a bio-fertilizer. Why are bio fertilizers and bio-control agents getting more acceptance all over the world?
Answer:
Roles of mycorrhiza as bio-fertiliser:
Mycorrhiza is a symbiotic association between the roots of some vascular plants and some fungi. In this association, the fungi develop hyphae (fine filaments of the fungal vegetative body) around the root tip or inside the cortex of the roots of the vascular plants.
The fungal hyphae can absorb phosphorus and nitrogenous nutrients from the soil very efficiently. It can also remove harmful heavy metals like lead, mercury, etc., from the soil to reduce soil pollution.
Mycorrhiza is formed in oaks, pines, orchids, and some crop plants. The fungi involved in the formation of mycorrhiza are Boletus sp., Amanita sp., Glomus, etc.
Reasons behind acceptance of biofertilizers and bio-control agents:
Chemical fertilizers are expensive. Production of these fertilizers needs large infrastructure and power. Chemical fertilizers reduce natural soil fertility and change soil pH. The same is applicable in the case of pesticides, these are very expensive and all of these materials increase environmental pollution.
However, in comparison with chemical fertilizers, the production cost of biofertilizers is negligible. Pest control by biological agents does not need any infrastructure at all.
Production of bio-fertilizer does not need heavy infrastructure and power. Moreover, bio-control is an eco-friendly procedure and biofertilizers do not cause soil pollution.
Bio-fertilizer and pest control by biological agents not only retain the natural resources of the earth but also prevent them from getting amalgamated with chemical precipitations. So bio-fertilizers and bio-control agents are getting more acceptance all over the world.
Practice Long Answer Questions on Microbial Benefits
Question 5. What is a pest? Write about the role of microbes in the biological control of pests.
Answer:
Pest:
Pests are species whose presence directly or indirectly affects the benefits, advantages, and welfare of human beings.
Examples: Tryporyza incestuous, Leptocoriza varicosis, Hispa armiger, Bandicota bengalensis, Bandicota indicia, etc.
Role of microbes in the biological control of pests:
WBBSE Life Science And Environment Class 9 Solutions
Question 6. What do you mean by biological pest control? Mention its advantages and disadvantages.
Answer:
Biological pest control:
The control of pests with the aid of biological agents (bacteria, viruses, protozoa, etc.) is known as biological pest control. Example-Use of bacteria, and birds to control pest moths.
Advantages:
1. Biofertilizers do not harm non-target organisms, they are very specific.
2. No toxic chemicals are used in their preparation, hence, there are no residues of such chemicals left in soil or water.
3. No bioaccumulation of chemicals in food chains occurs due to the use of biofertilizers.
4. Long-term usage of biofertilizers does not generate any resistance to pests.
Disadvantages:
1. A low level of pests has to be sustained for the maintenance of control agents.
2. Development and research of appropriate control agents is expensive and lengthy.
Understanding the Role of Microbes for Long Answers
Question 7. Write different characteristics or properties of bio-fertilizer. Mention the advantages and disadvantages of biofertilizers.
Answer:
Characteristics or properties of biofertilizers:
1. Biofertilizers contain living microorganisms.
2. They improve the soil texture and yield of plants.
3. They do not allow pathogens to flourish.
4. They are eco-friendly and cost-effective.
5. They protect the environment from pollutants.
Advantages of biofertilizers:
1. They are cost-effective.
2. They supplement chemical fertilizers.
3. They are eco-friendly.
4. They reduce the cost of the use of fertilizers, especially regarding nitrogen and phosphorus.
5. They improve the texture, structure, and water-holding capacity of the soil.
6. There are no adverse effects on plant growth and soil fertility due to the usage of biofertilizers.
Disadvantages of biofertilizers:
1. Biofertilizers require special care for long-term storage because they are alive.
2. They must be used before their expiry date.
3. If other microorganisms contaminate the carrier medium or if a wrong strain is used, they are not as effective.
4. They lose their effectiveness if the soil is too hot or dry.
Concepts Related to Microbes in Human Welfare for Long Answers
Question 8. Differentiate between organic manure and bio-fertilizer.
Answer:
Difference between organic manure and bio-fertilizer:
Sample Long Answer Questions from WBBSE Class 9 Life Science
Question 9. Differentiate between inorganic manure and bio-fertilizer.
Answer:
Difference between inorganic manure and bio-fertilizer:
WBBSE Life Science And Environment Class 9 Solutions
Question 1. Briefly explain the impact of light on living organisms.
Answer:
Effect of Light on living organisms:
1. In green plants, chloroplasts tend to concentrate on the surface of a leaf which gets more light.
2. In some plants, a span of daylight affects their flowering and other physiological activities. This phenomenon is known as photoperiodism. The plants, such as dahlia, sugarcane, strawberry, etc., flowers bloom during shorter daylight periods and are called Short Day Plants (SDP). The plants, such as peas, radishes, spinach, etc., flowers bloom during longer daylight periods and are called Long Day Plants (LDP).
In some plants, such as tomatoes, cucumbers, cotton, etc., a span of daylight does not have any significant impact on blooming. These are known as Day Neutral Plants (DNP).
WBBSE Class 9 Ecology Long Answer Questions
3. Light enhances the pigmentation of the skin. Animals living in hot and humid climates have darker body colours. Animals living in polar regions have pale body colours. Similarly, the human population living in strongly sunlit regions have darker body colour.
4. Photoperiod is the controlling factor for the breeding features of different animals. The animals, such as sheep, goats, deer, etc., breed during decreasing day length of autumn, known as Short Day Breeders (SDB).
Read and Learn More Class 9 Life Science Long Answer Questions
On the other hand, lemurs, horses, hamsters, etc., breed during increasing day length of spring and are known as Long Day Breeders (LDB). Also, there are certain animals, whose breeding is not affected by day length. These animals include guinea pigs, cats, rabbits, etc.
Important Long Answer Questions for Chapter 5 Life Science
Question 2 Explain the effect of temperature on the living world.
Answer:
Effect of temperature on living organisms:
1. Plants growing in desert regions have light-coloured body hairs, that act as heat reflectors. Their leaves are modified into spines and they have fewer stomata to reduce transpiration.
The overall surface area of these plants is less, compared to other plants. As a result, the area exposed to air is reduced, thereby reducing the rate of transpiration.
2. Plants growing in the hot but humid climate of the tropical region, have broad flat and thick green leaves to increase the rate of transpiration.
3. In amphibians, reptiles and fishes, body temperature varies with environmental temperature. These animals are, therefore, known as poikilothermic animals. On the other hand, birds and mammals maintain constant body temperature in any environment. These are known as homeothermic animals.
4. Some animals, such as toads, house lizards, ants, etc., can withstand a wide range of temperature variations in the environment. These are called eurythermal animals. Some animals, such as fishes and cnidarians cannot tolerate wide temperature fluctuation. These are called stenothermal animals.
WBBSE Life Science And Environment Class 9 Solutions
Question 3. Explain the effect of relative humidity on living organisms.
Answer:
Effect of relative humidity on living organisms:
1. Plants growing in moist environments have wider leaves with many stomata to dispose of excess water and these plants perform transpiration at a higher rate.
Certain plants like tomatoes and a few types of grass dispose of excess water as tiny droplets through special water pores, called hydathodes, situated along the edge of the leaves to get rid of excess water.
2. Animals living in desert regions have few sweat glands and discharge scanty urine and dry faeces. A desert reptile, Moloch horridus have uniquely designed spiny skin to reduce water loss and maintain body humidity. Insects living in desert regions bear a layer of waxy cuticles over their body to reduce water loss.
3. Plants growing in arid climates develop features that help them to resist atmospheric dryness. They have elaborate root systems, few leaves, fewer stomata, waxy leaf and stem surfaces, elaborate tap root systems, etc. to conserve and collect more water.
4. Excessive relative humidity is favourable for the growth of the fungal population. In moist weather, different pathogenic and non-pathogenic fungi grow. In moist weather, the population of bryophytes and pteridophytes also increase significantly.
Practice Long Answer Questions on Ecology
Question 4. Explain the role of different factors regulating population size.
Answer:
Factors regulating population size:
Four factors play a significant role in regulating the population size.
These are:
1. Natality
2. Mortality
3. Immigration
4. Emigration.
1. Natality:
Natality can be defined as the ratio of total live births to a population in a specified community or area, over a specific period of time. We may express natality or birth rate as the number of live births per 1000 of the population per year. It can be represented as the following equation-
B = \(\frac{nb}{N} x 1000, where, B = natality or birth rate, N = total number of individuals in a population, nb number of live births.
2 Mortality:
Mortality can be defined as the ratio of total deaths to a population in a specified community or area, over a specific period of time. Population size decreases with the increase in mortality of the individuals.
Death rate or mortality is often expressed as the number of deaths per 1000 of the population per year. It can be represented as the following equation.
D = [latex]\frac{nd}{N}\) x 1000, where, D = mortality or death rate, N = total number of individuals in a population, nd = number of deaths
3 Immigration: Immigration is the mass entry of individuals in a population in a given area, from some other place. Therefore, immigration increases the population size very quickly.
4 Emigration: Emigration, on the other hand, means the mass departure of individuals from a population in a given area, to some other place. By emigration, population size goes down abruptly.
Concepts Related to Ecosystems for Long Answers
Question 5. Discuss different levels of positive interspecific interactions in the living world.
Answer:
Positive interspecific interactions in the living world:
Positive interactions in the living world are collectively known as cooperation. In nature, several species live together in cooperation. Here, both or at least one of the species, involved in the relation, is benefited, but neither of them is harmed. This cooperative relationship between different species helps in better growth, reproduction and survival.
Cooperation may be of different types:
1. Symbiosis
2. Mutualism
3. Protocooperation
4. Commensalism.
These are described below:
1. Symbiosis:
Symbiosis is an interspecific cooperation, in which two species live in a close physical association and both are benefited some way or the other. Symbiosis may be obligate (both species entirely depend upon one another for survival) or facultative (both species do not depend on their partner for survival).
Example:
In lichens, algae and fungi develop symbiotic associations. Here, the fungus acts as a settling platform and provides water and mineral to the alga. In return, the alga synthesises food for both.
2. Mutualism:
Mutualism is the cooperation between two species, in which both are benefited but close physical association and nutritional interdependence between them is not evident. Example-Insects collect nectar and pollen from flowers. In exchange, they help in spreading pollen grains from one place to another that help in plant reproduction.
3. Protocooperation:
Protocooperation is a positive interspecific interaction, where both members are benefited but, they do not depend on one another for survival. Growth and survival of both species is possible even in the absence of this interaction. Mutualism between insect and flower.
Example:
Sea-anemone often rides on the shell of a hermit crab. Here sea anemone intakes discarded food of the hermit crab and in return protects it from the predators by its stinging cells. This relation is not obligatory because both can live independently.
4. Commensalism:
Commensalism is the cooperation between two species, where one of the members is benefits, but the other member is neither benefited nor harmed. In this relation, close association occurs between the two species, but nutritional interdependence is not developed.
Example:
Epiphytic orchids grow on the branches of big trees, but carry out photosynthesis independently. By this process, orchids escape predation, but the host tree is neither harmed nor benefited.
WBBSE Life Science And Environment Class 9 Solutions
Question 6. Discuss competition, predation and parasitism in the living world.
Answer:
Interactions in the living world:
In the living world, intraspecific and interspecific interactions involve two individuals, of which either both or one of the members is benefited and the other member sustains a loss, gets injured or dies. Among these interactions competition, predation and parasitism are important.
Study Guide for Class 9 Life Science Ecology Questions
These are described below:
1. Parasitism:
Parasitism is the most advanced type of interspecific interaction, in which one species depends upon other species for food or shelter or both. Here, the dependent member (parasite) is benefited, but the other member (host) is deprived.
Example:
Tapeworms (Taenia sp.), roundworms (Ascaris sp.), etc. are parasitic worms that draw nutrients from humans (host). Dodder plants (Cuscuta sp.) suck nutrients from the phloem of the host plants.
2 Competition:
Competition can be defined as a negative interaction, where members of the same or other species fight with each other to acquire a limited supply of environmental resources food, water, shelter and mates.
Competition is mainly of two types:
1. Intraspecific competition
2. Interspecific competition.
1. Intraspecific competition: In this competition, members of the same species fight among themselves for food and mate.
Example: Fighting among dogs or fighting among cats.
2. Interspecific competition: This competition takes place between members of two or more different species, for food and shelter.
Example: Sparrows quarrelling with common maina or dogs fighting with cats.
3. Predation:
Predation is another type of interspecific interaction, in which one species attacks another species to kill and consume it. Here, the attacker is known as the predator and the one, which is attacked, is called the prey. The predator obtains nutrition and energy from the prey.
Example:
Tigers kill deer, praying mantis kills other insects, pitcher plants trap insects, etc. In all the above examples, the former ones are the predators and the latter ones are the prey.
WBBSE Life Science And Environment Class 9 Solutions
Question 7. Write down a brief note on different types of parasites in living world.
Answer:
Different types of parasites:
From an evolutionary point of view, parasitism is the most advanced type of interspecific interaction, in which one species depends upon other species for food or shelter or both. Here, the dependent member (parasite) is benefits, but the other member (host) is deprived. Different types of parasites are described below.
Based on their position in the host body, parasites are classified into two types:
1. Ectoparasites: These parasites draw nutrients from outside the body of the host.
Example:
Lice, ticks, and bedbugs live on the body surface of mammals. In the case of parasitism in plants, the Dodder plant needs special mention. Dodder plant
(Cuscuta sp.) produces root-like structures, called haustoria, which penetrate the vascular bundle of the host and derive nutrition directly.
2. Endoparasites: These parasites live inside the body of the host and collect nutrients from them.
Examples: Tapeworms, roundworms, Plasmodium (malarial parasite), liver fluke, etc. live inside the human body.
On the basis of the dependence of parasitism, they may be of two types-
3. Obligatory parasites: These species completely depend upon a host to complete their life cycle.
Example: Tapeworms, roundworms, Plasmodium, etc. spend their life permanently as parasites.
4. Facultative parasites: These species can survive without the parasitic mode of life but can also adapt a parasitic life.
Example: The parasitic nematode Strongyloides stercoralis can also be free living.
Sample Long Answer Questions from WBBSE Class 9 Life Science
Question 8. Briefly describe the general structural aspects of an ecosystem.
Answer:
The structural aspect of the ecosystem:
An ecosystem constitutes two types of components or factors:
1. Abiotic factors
2. Biotic factors.
1. Abiotic factors:
Abiotic factors include the non-living components of the ecosystem. They have a direct impact on the life process of living organisms.
Various abiotic components of the ecosystem are:
1. Organic component,
2. Inorganic component
3. Physical component.
1. Organic component:
Different organic matters, such as carbohydrates, proteins, fat, etc. are obtained from the dead and decaying organic remains of plants and animals. These organic matter mix with the soil and produce humus, which plays a significant role in regulating soil fertility.
2. Inorganic component:
It includes various mineral elements (such as calcium, magnesium, salts of sodium, potassium, sulphur, etc.) and gases (such as oxygen, nitrogen, carbon dioxide, etc.). Green plants use these elements for synthesizing their own food.
3. Physical component:
The physical component of the ecosystem includes various factors, such as light, temperature, humidity, altitude, steepness of slope, and firmness of soil. Of these, the most important physical factor is light, more specifically sunlight. Green plants trap solar energy and convert it to chemical energy to prepare their own food by the process of photosynthesis.
2 Biotic factors: The living organisms constitute the biotic factors of an ecosystem.
Various components of biotic factors are:
1. Autotrophs
2. Heterotrophs.
1. Autotrophs:
All those organisms, capable of synthesizing their own food by photosynthesis or chemosynthesis, are known as autotrophs. All green plants, photosynthetic and chemosynthetic microorganisms are examples of autotrophs.
2. Heterotrophs:
The living organisms, which depend directly or indirectly on autotrophs for their nutrition are known as heterotrophs.
Heterotrophs may be classified into three types:
1. Consumers
2. Decomposers
3. Transformers
1. Consumers:
These organisms directly or indirectly consume autotrophs, especially green plants and plant products, to gain nutrition and energy. So, they are called consumers. Depending upon the nature of food they eat, consumers are classified into three types- (a) Primary consumers: These animals directly consume green plants or plant products for nutrient and energy. Example-Deer, cow, grasshopper, etc. (all herbivores).
2. Secondary consumers: These animals directly consume herbivores for nutrition. Example-Frogs, small birds, rat, lizards, etc.
3. Tertiary consumers: These are larger consumers, which feed on both primary and secondary consumers.
Example: Owl, tiger, lion, falcon, king cobra, etc.
2. Decomposers and transformers:
The organisms, which get their nutrients from dead organisms and decaying organic matter and in this process break the larger organic compounds into smaller molecules, are called decomposers. Different microorganisms (such as bacteria) and some fungi (such as Agaricus) belong to this group.
Some bacteria act upon those small organic molecules, that are the end products of decomposition. These bacteria completely break those organic molecules and return the elementary components in nature. They are called transformers.
WBBSE Class 9 Life Science Solutions
Question 9. How does energy flow through an ecosystem?
Answer:
Energy flow in the ecosystem:
Energy flow can be defined as the unidirectional transfer of solar energy, in the form of organic matter, from producers to the highest level of consumers, through different trophic levels via food chains.
Sun is the ultimate source of energy in all ecosystems. Only photosynthetic organisms are capable of trapping and transforming the light energy form the sun into chemical energy in the form of food.
This energy is transferred from producers to consumers through food chain, which is called flow of energy. Energy flow in an ecosystem occurs through the following three steps.
1. Acquiring energy:
All green plants and other photosynthetic microorganisms can trap radiant energy from the sun. Only 0.02% of the total energy of sun comes to the earth as light. Of this, only 0.1% is trapped by means of photosynthesis. This process is called acquiring energy.
2. Utilizing energy:
The light energy from the sun, trapped by the green plants, is oxidized during respiration to produce chemical energy. This energy is necessary to carry out different metabolic activities. This process is called utilization of energy.
3. Transfer of energy:
From the green plants, net primary production passes to different level of consumers through food chain. The herbivores or primary consumers directly get their share of energy from producers.
By respiration, primary consumers utilize a greater portion of the transferred energy. the remaining portion of the energy is then transferred to the higher level of consumers in the same way.
When energy flow occurs from one trophic level to another, subsequently an amount of energy is lost in the process which cannot be regained further.
Moreover, the energy that follows from producer to consumer, can never be returned to the producer. Hence, the flow of energy is always unidirectional.
According to famous scientist, Lindeman, out of the total energy produced or received in a particular trophic level, only 10% of it is transferred to the next trophic level.
This is known as Lindeman’s 10% law. As a result, a very less amount of energy is received by the members of the highest trophic level.
Question 10. With an example, describe how the biogeochemical cycle of a nutrient operates in nature.
Answer:
Biogeochemical cycle of a nutrient:
Living organisms obtain different nutrients (such as C, H2, O2, N2, S, P, Ca, etc.) from the environment through food and as respiratory gases. These elements act as structural components of a living body.
These elements are returned to the environment by excretion, respiration and decomposition of dead or decaying organic matter. Within the biosphere, several are structurally and metabolically important. elements are exchanged between the biotic and the abiotic components of the ecosystem.
This exchange of elements occurs through a cyclic path, known as the nutrient cycle or biogeochemical cycle. Here, the carbon cycle is discussed below as an example.
The carbon cycle refers to the cyclic exchange of carbon in the physical and biological systems:
1. Reservoir Pool: Carbon bed of the lithosphere act as a reservoir pool for carbon.
2. Cyclical Pool: The cyclic pool of carbon involves the atmosphere and the sea water.
3. Utilisation of carbon from nature: It involves two pathways
1. Biological path:
The biological path of carbon utilization involves activities of green plants and shelled molluscs. Green plants trap carbon within cellular compounds by photosynthesis. Shelled molluscs utilize carbon of CO2 to prepare their shell. The echinoderms from air to form the spinous body surface with ossicles, which is made up of calcium carbonate.
2. Physiochemical path: The physiochemical path of carbon utilization involves certain marine deposits, such as limestone, dolomite, feldspar, etc. absorb carbon (CO2) to prepare calcium carbonate (CaCO3).
4 Return of carbon to nature:
Carbon is returned to the environment by two pathways:
1. Biological path:
All living forms (except a few anaerobes) release CO2 by respiration. CO2 is released into the nature by decomposition of organic matters. After the death of molluscs and sea corals, their calcium carbonate rich shells are decomposed to produce CO2.
2. Physiochemical path:
Combustion of fossil fuel, wood, etc., forest fire and volcanic eruption produce huge quantity of CO2. This cyclic process of utilization and return of carbon to nature occurs at the same rate. This helps to maintain constant carbon content in the environment.
WBBSE Class 9 Life Science Solutions
Question 11. What are the features of energy flow in an ecosystem.
Answer:
The characteristics of energy flow:
1. Solar energy is the main source of energy in all ecosystem.
2. Energy flow is unidirectional.
3. Amount of energy gradually decreases along the trophic level.
4. Energy flow in an ecosystem occurs through three steps-acquiring of energy, utilisation of energy and transfer of energy.
5. Energy flow in an ecosystem obeys the first and second laws of thermodynamics.
6. In the year 1942, Lindemann formulated 10% law of energy flow. According to this law, only 10% of total energy of any trophic level is transmitted to next trophic level during energy flow through several trophic levels.
Question 12. Deseribe about the different levels of ecological organisation.
Answer:
Different levels of ecological organisation:
The various levels of ecological organisations are:
1. Organism:
It is the lowest level of organisation, which includes both unicellular and multicellular organisms. All the living species in this level exhibits all the characteristics required for the existence of life.
2. Population:
A population is a group of individuals of a single species living together within a particular geographic area. They inter breed and complete with each other for resources.
3. Community:
It refers to the several populations that interact and inhabit a common environment and are inter dependent.
4. Ecosystem:
It is a set of all living species and abiotic components existing and interacting in a given area. There is an interaction with both living and non-living components of the environment.
5. Biosphere:
It is highest level of organisation. It is the global ecological system which consists of all the living organism and other factors which supports life. Biosphere mainly refers to the part of the earth’s crust.
WBBSE Class 9 Life Science Solutions
Question 13 How do you build a pond ecosystem?
Answer:
Pond Ecosystem:
The pond ecosystem contains two main components i.e.,
1. Abiotic.
2. Biotic.
1. Abiotic components:
They are formed as a result of the mixture of some organic and inorganic materials. They have direct or indirectly effects in aquatic organisms in the pond. These includes-light, temperature, dissolved oxygen, carbon dioxide, other gases, pH of water, turbidity, and dissolved minerals.
2. Biotic components:
They are the living components which consist of:
1. Producers:
They are the aquatic green plants, which may be divided into two groups:
1. Microphytes (Phytoplanktons): They are microscopic autotrophs, which fix solar energy. Example-Spirogyra, Zygonema, Volvox, Oedogonium, etc.
2. Macrophytes: They are large plants, which manufacture complex food. Example-Pistea, Hydrilla, etc.
2. Consumers:
They are those heterotrophic organisms, which consume producers as food.
Their types are:
1. Primary consumers: These herbivorous animals depend on autotrophic organisms such as microscopic plant eaters or zooplanktons, molluscs, beetles, Cyclops, Daphnia, etc.
2. Secondary consumers: These are primary carnivores, which depend on herbivorous animals for food.
Example: Insects, fish, frogs, crab, etc.
3. Tertiary consumers: These are the second grade of carnivores. They feed upon plants and animals (secondary consumers), therefore are called carnivores.
Example: Large fishes, frogs.
3. Decomposers:
Most of the decomposers of the pond ecosystem are saprophytes but some parasites are also found. Bacteria, and fungi, like Aspergillus, Cladosporium, Rhizopus, Alternaria, Fusarium, Saprolegnia, etc. are decomposers.
Generally, the decomposers either live in the soil layer beneath water or in the mud. They act on the dead and decayed organic matter of plants and animals and supply raw materials to the producers.
Understanding Ecosystem Dynamics for Long Answers
Question 14. Describe the structure of the forest ecosystem.
Answer:
Forest ecosystem:
The forest ecosystem contains two main components i.e.,
1. Biotic
2. Abiotic.
1 Biotic component:
1. Producer organisms: In a forest, the producers are mainly trees. Apart from trees, climbers, epiphytes, shrubs and ground vegetation. Dominant species of trees in major types of forest ecosystems are-Tectona grandis, acer, betula, picea, pine, cedrus.
2. Consumers:
In a forest, consumers are of three main types:
1. Primary consumers: These are herbivores which feed directly on producers.
Example: Ants, beetles, bugs, spiders, etc. feeding on tree leaves. Larger animals like elephants, deer, giraffe, etc. grazing on shoots and/or fruits of trees.
2. Secondary consumers: These are carnivores and feed on primary consumers.
Examples: Birds, lizards, frogs, snakes and foxes.
3. Tertiary consumers: These are secondary carnivores and feed on secondary consumers. These include top carnivores like lions, tigers, etc.
3. Decomposers:
These include a wide variety of saprotrophic microorganisms, like bacteria (Bacillus sp., Clostridium sp.), fungi (Aspergillus sp., Ganoderma sp., Fusarium sp.), actinomycetes (Streptomyces sp.). They attract dead or decayed bodies of organisms and thus decomposition takes place. Therefore, nutrients are released for reuse.
2 Abiotic components: These include basic inorganic and organic compounds present in the soil and atmosphere. In addition, dead organic debris is also found littered in forests.
WBBSE Life Science And Environment Class 9 Solutions
Question 1. Discuss the environmental and economic importance of a forest.
Answer:
Importance of a forest:
1. Watershed protection:
Afforestation along the slope of the watershed prevents runoff and reduces the deposition of slits in the riverbed. Some plants with mycorrhizal roots absorb heavy and toxic metals from the soil and reduce the chance of water toxicity.
2. Atmospheric regulation:
The scarcity of plants and excessive industrialization in urban areas reduces O2 and increases CO2 content in the atmosphere. Forest regulates O2, and CO2 balance. By respiration, organisms release CO2 and absorb O2 from the atmosphere.
By the process of photosynthesis, green plants of a forest release O2 and absorb CO2. In this way, the balance of O2 and CO2 in the atmosphere is maintained.
3. Erosion control:
Erosion means washing or blowing away of top layer of soil. Forests prevent soil erosion by several methods.
Read and Learn More Class 9 Life Science Long Answer Questions
They are:
1. The branches of roots firmly bind the soil particles with the ground.
2. The dense leaves of the forest prevent raindrops from hitting the soil particles directly and loosening it from the upper layer of soil.
3. The litter formed by the leaves on the forest floor, partly decomposes to form sticky humus. This sticky humus increases the adhering capacity of the soil particles and prevents soil erosion.
WBBSE Class 9 Natural Resources Long Answer Questions
4. Local use:
Humans exploit forests in different ways. People living in nearby villages collect firewood from the forest. Forests provide honey, timber, resin, honey, cotton, fur, wool, meat (from herbivores), etc. that are collected and marketed.
5. Productive use:
From a productive point of view, the forest has immense importance. Timber is the main economically important product of the forest, used to prepare sleepers, posts, log houses, plywood, laminates, galleries, furniture, etc.
Ecotourism is another productive aspect of the forest, from which the government earns a huge amount of revenue. Honey, rubber, and several medicinally important materials are collected from the forest.
Question 2. Briefly discuss the causes of deforestation.
Answer:
Causes of deforestation:
1. Subsistence agriculture:
It is an unscientific method of farming, where farmers concentrate on growing enough food for themselves and their families. They cut trees and burn smaller vegetation to prepare land for cultivation and cattle grazing.
2. Indiscriminate felling of trees:
The growing population has increased the demand for wood products, starting from match-sticks to furniture. Accordingly, the price of wood has also been increased. Due to this high price of wood, traders encourage indiscriminate felling of trees.
3. Urbanisation:
For the development of the state infrastructure, roads, and railway tracks are laid through forestland. Moreover, miners acquired the forestland for oil, coal, and ore mining. This level of human intervention has affected the lifestyle of both animals and plants and led to habitat fragmentation.
4. Forest fire:
In drier seasons, the local farmers and forest communities burn dry grasses to expand grazing areas. A high concentration of oxygen in the forest atmosphere drives this small fire into a firestorm. It goes out of control and destroys hundreds of trees and many smaller and bigger wild animals.
5. Desertification:
Rivers and streams flowing through forestlands often carry industrial pollutants. These toxic materials cause soil pollution, which leads to polluting the forest ecosystem.
WBBSE Life Science And Environment Class 9 Solutions
Question 3. Describe the consequences of deforestation.
Answer:
Consequences of deforestation:
1. Global warming: Due to deforestation and the rapid pace of industrialization, the concentration of greenhouse gases like CO, increases in the atmosphere. This results in global warming.
2 Climatic change: Transpiration by trees increases humidity in the atmosphere, which in turn enhances the chance of rainfall. In many parts of the world, the rate of rainfall has dropped significantly due to deforestation.
3 Change of soil character and erosion: The litter, deposited in the forest floor, decomposes to form humus, which keeps the soil healthy and moist in normal situations. Due to deforestation, the soil gets exposed to the sun and dries out. Moreover, soil particles become loose without binding of roots. Due to this, rain and wind wash off and blow away soil particles, reducing the chance of humification and resulting in soil erosion.
4 Flood and drought: The incidence of flood and drought has increased in every part of the world due to deforestation.
5. Wildlife extinction:
Forests provide habitat for millions of species of flora and fauna. Deforestation makes them homeless. As a result, a certain number of species as well as part of wildlife go extinct.
6. Environmental pollution:
Deforestation results in a decrease in atmospheric oxygen levels. At the same time carbon dioxide increases, which is a cause of air pollution. Mycorrhiza. developing in the root system of some trees can remove heavy and toxic metals from the soil. In the case of deforestation, soil becomes polluted.
Important Long Answer Questions for Chapter 5 Life Science
Question 4. Why should we conserve forests? Mention a few methods of forest conservation.
Answer:
Reasons for forest conservation:
Conservation is the protection, augmentation, and scientific management of resources so as to maintain them at their optimum level providing benefit to the present as well as future generations. Forests must be conserved because of their immense economic, protective, and regulative properties.
Forest conservation is important:
1. To maintain the ecosystem of the forest,
2. To maintain O2-CO2 balance in the environment,
3. To maintain the supply of forest products like timber, food, etc.,
4. To maintain the natural beauty and livelihood of the local people.
Methods of forest conservation:
1. Afforestation: It is the growth of forests on unprotected barren lands.
2. Reforestation: It is developing forest cover in the area that has been damaged or cleared during exploitation.
3. Separation of commercial forestry: Useful plants required by industry should be planted separately preferably on waste land.
4. Grazing: Grazing should be regulated according to the availability of pasturage.
5. Social Forestry: It is the growing of useful multipurpose trees and shrubs on common village lands, roadsides, railsides, etc. by cooperative efforts of people of the area. The plants provide fodder, small timber, and firewood to villagers.
6. Agroforestry: Multipurpose trees and shrubs are planted on the sides of crop fields to provide fodder, fuel, and timber.
Both social forestry and agroforestry reduce pressure on the forests. Trees are also planted at all vacant places and along roads in urban areas (urban forestry) to reduce air and noise pollution.
Practice Long Answer Questions on Natural Resources
Question 5. Mention the uses of water. Briefly describe the causes of water scarcity. Uses of water
Answer:
Water is an essential component of life. Water is one of the most vital natural resources on Earth for life to sustain. The availability and the quantity of water have always played a significant part in determining not only where the population can grow but also their quality of life. It is used in several ways.
1. Drinking:
Water is the most essential and universal drink necessary for life.
2. Agriculture and industrial purpose:
A large quantity of water is used for irrigation of crop fields. Different industries, such as metal, paper, chemical, wood, petrochemical, etc., and boilers of power plants require large quantities of water. Water is used as raw material, solvent, coolant, and washing medium.
Causes of water scarcity:
1. Drop in rainfall:
Rainfall has dropped radically in different parts of the world, resulting in moderate to severe water scarcity.
2. Global warming:
Excessive heat dries out surface water. But this loss is not totally replenished by rain.
3. Overutilization of water:
Over-utilization of groundwater is a result of poor water management, which leads to water scarcity and increased chance of arsenic contamination.
4. Pollution: Disposal of sewage water in streams and lakes is a wasteful technique. By this process, sources of freshwater are polluted and wasted. Tomod me
WBBSE Life Science And Environment Class 9 Solutions
Question 6. How is rainwater utilized to counter the scarcity of fresh water? Mention the advantages and disadvantages of rain water harvesting.
Answer:
Utilization of rainwater:
Rainwater is the largest source of fresh water. By scientific harvesting of rainwater, freshwater scarcity can be controlled to a great extent. Rainwater harvesting is a simple and effective method of water management by which rainwater is collected, stored, and used to meet the demand for fresh water.
The easiest and most popular method is rooftop rainwater harvesting. In this process, rainwater pipes of the roof are connected to a ground-level or underground reservoir.
The rainwater is stored in the reservoir and is used according to necessity. This water can be used directly for any non-potable purposes like watering plants, washing and cleaning, bathing, and toilets.
For cooking and drinking, this water must be disinfected and filtered. For using rain water at the community level, reservoirs of all premises are connected to one or more large community reservoirs.
Finally, this water is treated and disinfected centrally and then pumped to the overhead water supply tank or the main well of the village. Advantages and disadvantages of rainwater harvesting
1. Advantages:
1. Rainwater is generally free from germs and contaminants.
2. It is soft water with a slightly acidic pH and does not contain any salt.
3. Rainwater contains no corrosive substances, so it does not harm water pipes and reservoirs.
2 Disadvantages:
1. Rainwater harvesting is not practiced in areas with excessive suspended particulate matter in the air.
2. Toxic gaseous materials pollute the atmosphere in regions near chemical industries and fertilizer factories.
3. These gaseous pollutants mix with rain water and make it harmful.
Concepts Related to Resource Management for Long Answers
Question 7. Briefly describe different sources of food for human consumption.
Answer:
Different sources of food for human consumption:
1. Crop production:
The maximum quantity of food we consume is plant products. These include cereals (paddy, wheat, maize, millets, etc.), pulses (moong, masur, gram, pea, etc.) and oil seeds. (mustard seed, sunflower seed, groundnut seed, rape seed, etc.)
2. Horticulture:
Horticulture includes the cultivation of fruits, vegetables, nuts, seeds, herbs, etc. We get fruits and vegetables from horticultural farms. The fruits and vegetables which we use in cooking, are also horticultural products.
3. Cattle farming:
This industry is involved in the breeding and rearing of animals like cows, goats, pigs, etc. It provides us with animal products like meat and milk.
4. Poultry:
This industry is involved in breeding and rearing domestic birds like chickens, ducks, etc. This industry provides us with poultry products like meat and eggs.
5. Fishery:
Fisheries are meant for scientific breeding and rearing of fishes. Fisheries supply fish to our platter.
Question 8. Briefly describe the situation of food scarcity on a global basis. Mention the impacts of food scarcity on Earth.
Answer:
Global food scarcity:
During the last century, industrialization and urbanization have reached their peak. This situation has pushed agriculture already to the back row. Now the rate of agricultural production cannot meet the global demand for food crops.
The environmental changes and increasing population have aggravated this problem. All these factors have developed a scarcity of food all over the world. The situation has become more adverse in poorer and developing countries.
Out of 70 billion of the total world population, about 10 billion have been suffering from malnutrition and partial starvation. A few million are dying out of starvation or diseases caused by malnutrition. People from Africa, Latin America, and Asia are the main victims of food scarcity.
Impact of food scarcity:
Food scarcity is not only taking lives due to starvation and malnutrition, besides these, it also has some other impacts on human life and the environment. To increase crop production, a land is cultivated two or three times in a year.
In developing countries, chemical fertilizers are applied indiscriminately to increase yield. By this practice, the natural fertility of soil is lost, also the soil pH changes. Forest lands are encroached upon by farming.
This practice results in deforestation which is followed by soil erosion and flood. Random use of pesticides in the crop fields causes soil and water pollution that may result in many incurable diseases. Irrigation of crop fields by suction of underground water is reducing the underground water reserve and causing arsenic pollution.
Study Guide for Class 9 Life Science Natural Resources Questions
Question 9. Refer to a specific incident related to the world food problem. Give examples of different alternative food sources.
Answer:
The special incident related to the world food problem:
Between July 2011 and mid-2012, a severe drought affected the entire East Africa region. The drought caused a severe food crisis across Somalia, Ethiopia, and Kenya that threatened the livelihood of 9.5 million people. The United Nations officially declared famine in two regions in the southern part of Somalia.
Alternative food sources:
To meet the additional demand for food, scientists and nutrition experts have found dietary potentials in some plant products, other than the common food materials.
1. Moringa oleifera has incredible nutritional value. Many edible parts, like fruits, seeds, leaves, and flowers are rich in protein, iron, Vitamin A, and Vitamin C. It also has great medicinal importance.
2. Yam bean contains enough carbohydrates, dietary fibers, and Vitamin C. It can be consumed raw as salad or cooked, baked, and even fried. Yam bean seeds contain oil.
3. Sago is a carbohydrate-rich matter, extracted from the stem of some palm trees. The granular shape is obtained by mechanical processing. It is tasty and has good nutritive value.
4. Gum Arabic is used to prepare chewing gum. Gaur gum is applied as a thickener in confectionary formulations.
5. Green gaur beans are eaten as vegetables and are used as fodder.
WBBSE Life Science And Environment Class 9 Solutions
Question 10. Discuss the causes of the world food problem.
Answer:
Causes of world food problem:
1. Increase in price of food:
For the last three decades, the price of food has been increasing globally. Due to high price rises, people in developing countries are facing serious problems.
2. Old method of farming:
The practice of conventional farming like monoculture (without crop rotation), using of low yielding seed varieties, using of chemical fertilizers, farming without soil testing and lack of coordination between farmers and marketing sectors are the main reasons for food problems in developing countries.
3. Climatic change and natural calamities:
The scarcity of rainfall or excessive rain may affect the production rate. Natural calamities, like floods or droughts, also reduce the productivity of food throughout the world.
4. Erosion of soil and soil pollution:
Soil erosion reduces the land, available for cultivation. Extensive use of chemical fertilizer reduces soil fertility and productivity. This is another cause of food problems.
5. Population explosion:
On average, 80 million people are born every year. But yearly production of food does not always reach that level to feed those new mouths. Therefore, an increase in the total population also increases food scarcity.
Sample Long Answer Questions from WBBSE Class 9 Life Science
Question 11. Classify the resources of energy on the basis of use. Mention the importance of conservation of energy resources.
Answer:
Classification of energy resources:
1. Conventional energy resources:
Conventional energy resources are those which have been traditionally used for many years. These resources are also widely used at present and are likely to be depleted. Examples are petroleum, natural gas, and hydel power.
2. Non-conventional energy resources:
Non-conventional energy resources are alternate energy resources to conventional energy resources which are being considered to be used on a large scale. Conventional energy resources are likely to be depleted in about 50-60 years and non-conventional energy resources should be fully developed by then to meet the energy- requirement.
Examples: Solar energy, wind energy, geothermal energy, tidal power, biogas, etc.
Importance of conservation of energy resources:
1. Energy is of the basic needs of life, therefore resources of energy must be conserved.
2. The conventional resources of energy, especially coal and petroleum are non-renewable, therefore they must be conserved for future generations.
Question 12 Mention three basic steps towards the conservation of energy resources. Mention the different uses of energy.
Answer:
Basic steps towards conservation of energy resources
Steps towards conservation of energy resources are as follows:
1. Thermal power generation is to be regulated to conserve coal.
2. Conventional sources of energy are to be replaced by non-conventional energy sources as far as practicable.
3. Misuse and wastage of energy resources must be cut down substantially.
Different uses of energy:
1. Domestic use:
In rural areas, wood, coal, and kerosene oil are utilized for heating and lighting purposes. In urban areas, energy is used for cooking, lighting rooms, heating, cooling, running electronic gadgets, washing machines, dishwashers, vacuum cleaners, water suction pumps, etc.
2. Commercial use:
In commercial buildings, such as shops, malls, hotels, and restaurants, energy is used for lighting, cooling, heating, and running utility gadgets.
3. Industrial use:
In industries, coal, oil, and natural gas are used for heating, burning, and melting purposes. Lighting and running machines depend upon electrical energy.
4. Use in transport:
Most of the vehicles, ranging from motor-bikes to airplanes, motor-boats to huge ships, run on petroleum-based fuels.
Nowadays, atomic energy is used to run huge submarines and aircraft carriers.
Question 13. Mention the methods of energy conservation in daily life.
Answer:
Method of energy conservation in daily life:
1. Lighting:
Walls to be painted in a lighter shade. Lamps should be kept dust-free. Incandescent bulbs need to be replaced with CFL to LED lamps. Electronic chokes be used instead of copper chokes.
2. Fans:
Fans are to be switched off before leaving the room. Electronic regulators be fitted.
3. Electric iron:
Ironing is to be done at the right temperature. The sprayer is to be used for moistening.
4 Kitchen appliances:
Grinders should be used for wet grinding. Machines are not to be run in over or under-load conditions. The door of the microwave-oven is not to be opened frequently to check food. Flat bottom pans are to be used for the induction oven.
5. Gas oven:
Cooking should be done in regulated flame. Pressure cookers are to be used as much as possible. Pans are to be kept covered while cooking. Before cooking items are to be allowed to reach room temperature after taking them out of refrigerator.
6. Water heater:
Solar water heaters are to be used to replace electric water heaters.
7. Electronic devices:
Before leaving the room even for short intervals, TV and audio systems should be turned off.
8. Computers:
Computer monitor to be turned off during long time downloading.
9. Refrigerator:
Star-rated energy-saver models are to be used. Frequent opening of the door should be avoided. Door padding should be air-tight.
10. Washing machines:
Washing machines should be run in full load condition at optimum water level. Perfect water and detergent quantity should be maintained.
11. Air conditioners:
Energy-saving star-rated equipment is to be installed and to be selected according to cooling capacity and room size. The outdoor unit is to be fitted in a shady place. Filters should be cleaned regularly. The doors and windows of the room are to be sealed perfectly.
Understanding Sustainable Development for Long Answers
Question 14. Mention the need for the conservation of natural resources and classify natural resources.
Answer:
Need for conservation of natural resources:
1. To support life by supporting ecological balance.
2. To ensure that the future generation will be able to access the resources.
3. To preserve the biodiversity.
4. To ensure the survival of the human race.
Classification of natural resources:
