WBBSE Solutions For Class 9 Life Science And Environment Chapter 2 Major Organs Of Human Body And Their Function

Chapter 2 Levels Of Organization Of Life Summary

1. A group of tissues having a common origin and those having the same function is collectively called an organ.
2. We have many organs like skin, stomach, pancreas, lungs, heart, spleen, kidney, liver, brain, spinal cord, testes, ovary, etc.
3. Each of these performs different functions.
4. The stomach is an organ of the digestive system related to the digestion of foodstuffs.
5. The heart is an organ that deals with the circulation of blood.
6. The kidney is an organ that helps to excrete waste products from our bodies.

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Chapter 2 Levels Of Organization Of Life Major Organs Of The Human Body And Their Function Long Answer Type Questions

Question 1. What is skin? Mention its distribution in the human body and discuss its functions.

Answer:

Skin:-

The skin is the outer covering of the human body and is considered the largest organ.

The skin consists of two layers:

1. Epidermis and
2. Dermis.

Distribution of skin:

The skin is spread throughout the body surface and guards the underlying muscles, bones, ligaments and internal organs.

Functions of skin:

The functions of the skin are as follows:

1. The skin protects our body from mechanical injuries.
2. Enzymes and salts, secreted through sweat, kill bacteria and other germs.
3. Sensory cells in the skin help us to feel the heat, touch, pressure, etc.
4. Skin absorbs sunrays to synthesize vitamin D for the body.

Question 2 Mention the location of the stomach in the human body. Discuss its functions.

Answer:

WBBSE Life Science And Environment Class 9 Solutions

Location of the human stomach:

The stomach is situated on the left side of the upper abdomen, just below the muscular diaphragm.

Functions of the stomach:

The functions of the human stomach are as follows:

The stomach is a large ‘J’ shaped sac-like structure that receives food from the esophagus, stores it for some time, and acts as a site of digestion of protein and fat.

HCl, secreted from the oxyntic cells of the stomach, helps in activating gastric enzymes.

Activated pepsin, present in gastric juice, acts upon proteins to break it into smaller derivatives, called peptones.

4. Lipase, present in gastric juice, helps in the hydrolysis of fat.
5. As the pH inside the stomach is acidic, microbes find it difficult to survive within it. Therefore, most microbes of the digestive flora remain within the gut and not in the stomach.

Question 3. Mention the location of the liver in the human body. Discuss its functions.

Answer:

Location of the liver:

The liver is present on the right ventral side of the upper abdomen, just below the diaphragm.

Functions of the liver:

The functions of the human liver are as follows:

1. The liver secretes bile, which neutralizes the acidic contents of the stomach.
2. Bile salts emulsify fat and help in its digestion.
3. Liver primarily absorbs nutrients from the blood before supplying it to different parts of the body.
4. It acts as the site of several metabolic activities.
5. Urea is synthesized within the liver.
6. The liver detoxifies various harmful components of the blood, like urea.
7. It helps in the synthesis of blood-coagulating components like prothrombin, fibrinogen, etc.

Question 4. Mention the location of the pancreas in the human body. State its functions.

Answer:

Location of the pancreas:

Pancreas is an irregular, elongated gland situated in the abdominal cavity below the stomach, extending from the duodenum to the spleen.

Functions of the pancreas:

The functions of the pancreas are as follows:

1. It secretes different digestive enzymes for the digestion of proteins, carbohydrates, and fats. The enzymes are trypsin, amylase, and lipase.
2. The pancreas produces essential hormones like insulin, glucagon, and somatostatin in the body.

WBBSE Life Science And Environment Class 9 Solutions

Question 5. Mention the location of the heart in the human body. State its functions.

Answer:

Location of heart:

The heart is located in the thoracic cavity between the two lungs. It remains slightly tilted towards the left.

Functions of heart:

The functions of the human heart are as follows:

1. Pumping of the heart helps the blood to flow through the blood vessels of the body.
2. It drives oxygenated blood from the left ventricle through systemic circulation to different organs and tissues of the body.
3. Deoxygenated blood from the right ventricle goes out to the lungs through the pulmonary circulation.
4. The heart receives deoxygenated and oxygenated blood into its right auricle and left auricle respectively.

Question 6 Mention the location of the kidney in the human body. State its functions.

Answer:

Location of the kidney:

Kidneys are held at the back wall of the abdominal cavity on either side of the vertebral column. The right kidney is positioned slightly lower than the left one.

Functions of kidneys:

The functions of kidneys are as follows:

1. Formation of urine by filtration of blood.
2. Maintenance of water and electrolyte balance of our body.
3. Regulation of blood pressure by secretion of renin.
4. Control of formation of RBC by secretion of erythropoietin.

WBBSE Life Science And Environment Class 9 Solutions

Question 7. Mention the location of the spleen in the human body. Mention the functions of the spleen.

Answer:

Location of the spleen:

The spleen of the human body is located on the upper far left side of the abdomen, below the left side of the stomach.

Functions of the spleen:

The functions of the spleen are as follows:

1. In the embryonic state, the spleen acts as the site of RBC formation.
2. In adults, it produces lymphocytes (B-cells and T-cells) to help the proper functioning of the immune system.
3. The spleen separates out and removes damaged, inactive, and aged RBC from the bloodstream.
4. It stores large quantities of RBC and leucocytes and releases them into the bloodstream according to the need of the body.

Question 8. What is the ovary? Mention the position of the human ovary and state its functions.

Answer:

Ovary:

The primary sex organ or gonad of the female body is called the ovary.

Location of the ovary:

Human ovaries are located at the two sides of the lower abdominal cavity in females. Each ovary is an almond-shaped structure, which is held in the abdominal wall with a thin membranous structure, a fibrous cord, known as the ovarian ligament.

Functions of the ovary:

The functions of the human ovary are as follows:

1. Several primordial germ cells are present in the ovary, which ultimately mature as ovum or female reproductive cells.
2. The ovary secretes hormones like estrogen and progesterone. These two female hormones help to maintain the feminine. features and reproductive cycle in females.
3. The hormone relaxin, secreted from the ovary, facilitates labor during childbirth.

WBBSE Life Science And Environment Class 9 Solutions

Question 9 What is testis? Mention its location in the human body and state its functions.

Answer:

Testis:

The primary sex organ or gonad of the male body is called the testis.

Location of the testis:

Human testis are paired structures, which are held in a sac-like structure, called the scrotum, outside the lower abdomen in males. These are placed between the penis and anus.

Functions of the testis:

The functions of testis are as follows:

1. Male gametes (spermatozoa) are formed within the seminiferous tubules of the testis.
2. Spermatozoa are nourished and stored inside the testis.
3. Testis secretes a hormone, named testosterone, which controls the development of masculine features like the formation of a beard, muscular body, etc., in adult males. It also controls the maturity of spermatozoa.

Question 10. Mention the location of the spinal cord in the human body. Discuss its function.

Answer:

Location of the spinal cord:

The long, hollow, cylindrical structure extending from the posterior part of the medulla oblongata in the brain upto the level of first lumber vertebra in the neural canal of the vertebral column, is known as the spinal cord.

Functions of the spinal cord:

The functions of the spinal cord are as follows:

1. The spinal cord receives nerve impulses from the brain and conducts it to the muscles and visceral organs.
2. The spinal cord plays a role in the perception of senses such as touch, pressure, temperature, and pain.
3. The spinal cord controls different types of unconditioned reflexes.

Question 11. Mention the location of the brain in the human body. Discuss its function.

Answer:

Location of the brain:

Brain and spinal cord Brain is the swollen anterior part of the central nervous system which is covered by meninges, remains protected inside the skull and has gray matter on the outer side and white matter on the inner side.

Functions of the brain:

The functions of the brain are as follows:

1. The brain processes all sensory information like vision, smell, hearing, taste, touch, etc., and generates responses accordingly.
2. The brain acts as the center for memory, intelligence, thinking, and all other mental activities.
3. Coordination among all organs of our body and their activities are maintained by the brain.

WBBSE Life Science And Environment Class 9 Solutions

Chapter 2 Levels Of Organization Of Life Major Organs Of The Human Body And Their Function Short Answer Type Questions

Question 1 What is meant by organ?

Answer:

Organ:-

An organized group of various specialized tissues that carry out a specific function of the body, is called an organ. Example-Heart, brain, etc.

Question 2 What is a sebaceous gland? What is sweat?

Answer:

Sebaceous gland: The gland present in the dermis layer of the skin, that secretes an oily substance called sebum, which keeps the skin smooth, is called the sebaceous gland.
Sweat: Sweat glands of skin produce aqueous fluid called sweat. It excretes water, NaCl, urea, amino acids, CO₂,

Question 3. Name the two layers of skin. Write the function of sweat.

Answer:

The two layers of skin:

1. Epidermis
2. Dermis.

The function of sweat: Excretion and cooling effect.

Question 4. Define Melanocyte. State its function.

Answer:

Melanocyte:

A cell in the skin and eyes that produces and contains the pigment called melanin. They are located in the layer of basal cells at the deepest part of the epidermis.

Functions:
1. Melanocyte produces a pigment called Melanin.
2. Melanin protects against UV-induced DNA damage by absorbing and scattering UV radiation.

Question 5. Why does your skin change color in the sun?

Answer:

Skin Change Color In The Sun Because:-

Exposure to ultraviolet radiation from the sun causes changes to skin color. It occurs not because of increased melanin production but due to the redistribution of melanin stored in keratinocytes in the upper layers of the skin.

WBBSE Life Science And Environment Class 9 Solutions

Question 6 Why bleeding does not occur due to cut or de to cut or scrape on the epidermis of the skin?

Answer:

There are no blood vessels in the epidermis. Due to this reason, bleeding does not occur even if the epidermis is cut or scraped.

Question 7. Mention the location and function of the peptic cell.

Answer:

Location And Function Of The Peptic Cell:-

The peptic cell is located in the mucous layer of the stomach. It is also known as the chief cell.

Function: It secretes a substance called pepsinogen which gives rise to pepsin, an enzyme that helps in the digestion of protein.

Question 8. Mention the location and function of the oxyntic or parietal cell.

Answer:

In the stomach, the mucous layer contains oxyntic or parietal cells that secrete HCl.

Function

• Parietal cells secrete HCl and Intrinsic factors.
• HCl helps pepsin to digest protein up to peptone.
• HCl hydrolyses foods in the stomach.
• HCl kills bacteria and other germs engulfed with foods.
• Intrinsic factor helps in the absorption of Vitamin B₁₂.

Wbbse Class 9 Life Science Solutions

Question 9 What do you mean by gastric glands? What is its function?

Answer:

Gastric Glands And Its Functions:-

Gastric glands: microscopic tubular glands, found in the epithelium of the stomach.

There are three types of cells which are as follows:

1. Peptic cells or Chief cells
2. Parietal cells or Oxyntic cells.
3. Mucous cells or Goblet cells.

Function: The gastric juice secreted by the gastric glands of the stomach helps in protein metabolism.

Question 10 What is pleura? Write its function.

Answer:

Pleura: The lungs are surrounded by a thin transparent double-layered membrane called pleura.

Function:
1. Pleura protects the lungs from mechanical injury.
2. It helps in the free movement of the lungs.

Question 11 What is alveoli? State its function.

Answer:

Alveoli:

Alveoli are balloon-shaped air sacs present at the very end of the respiratory tree and are arranged in clusters throughout the lungs.

Function: The function of alveoli is to exchange oxygen and carbon dioxide molecules to and from the bloodstream.

Question 12 What is a mixed gland?

Answer:

Mixed Gland:-

They have both an exocrine and an endocrine part. The exocrine part secretes juices with enzymes that come out through the duct. The endocrine part secretes hormones which is carried directly by blood or body fluids.

Examples: Pancreas, and testis.

Wbbse Class 9 Life Science Solutions

Question 13 Name two enzymes and two hormones secreted by the pancreas.

Answer:

Enzymes And Hormones Secreted By The Pancreas:-

Trypsin and chymotrypsin are the enzymes released by the pancreas. Insulin and glucagon are two hormones secreted from the endocrine part of the pancreas.

Question 14 Mention the location and functions of the human lungs.

Answer:

Location: The two lungs are situated at the two sides of the chest cavity within the rib cage.

Functions:
1. Lungs help in the intake of O₂-rich air by inspiration and expulsion of CO₂-rich air by expiration.
2. Lungs also help in the excretion of a few other toxic materials by expiration.

Question 15 Name a hormone and the major enzyme secreted by the stomach.

Answer:

Gastrin is a hormone secreted by the stomach and pepsin is the major enzyme secreted by the stomach.

Question 16 Name the two major blood vessels of the kidney and name the protective layer of the kidney.

Answer:

The two major blood vessels of the kidney are the renal vein and renal artery and the protective layer of the kidney is called a capsule.

 

Chapter 2 Levels Of Organization Of Life Major Organs Of The Human Body And Their Function Answer In A Single Word Or Sentence

Question 1 Which two layers constitute our skin?
Answer: Epidermis and hypodermis constitute our skin.

Question 2 Which is the largest sense organ of our body?
Answer: Skin is the largest sense organ of our body.

Question 3 Which organ of our body carries the sensory cells for the perception of heat and pressure?
Answer: Skin

Question 4 Mention the two functions of skin.
Answer: Two functions of the skin are:
[1] The skin helps in excretion and water regulation.
[2] It also helps in the regulation of body temperature.

Question 5 Which organ of our body can store the food for some time during digestion?
Answer: Stomach

Question 6 Which organ of the human digestive system acts as the killing field for most of the microbes, taken with food?
Answer: Stomach

Question 7. Besides killing germs within the consumed food, what other function does HCI do inside the stomach?
Answer: Besides killing germs within the consumed food, HCl activates pepsinogen into pepsin inside the stomach.

Question 8 Name a highly extensible sac-like structure located at the left side of the upper abdomen.
Answer: Stomach

WBBSE Class 9 Life Science Question And Answer

Question 9. The lumen of which organ always remains in an acidic state?
Answer: The lumen of the stomach always remains in an acidic state.

Question 10 Name the organ of a human body which helps in neutralising the acidic food mass, coming into duodenum from the stomach.
Answer: Liver secretes bile, which neutralises the acidic food mass, coming into duodenum from the stomach.

Question 11 The proteolytic enzyme, pepsin is secreted by which cell of stomach?
Answer: Peptic or chief cell of stomach secretes pepsin in an inactive form called pepsinogen.

Question 12 Which organ is located just below the stomach at the left side of the abdomen?
Answer: Spleen

Question 13 Name the local hormone secreted by stomach.
Answer: Gastrin

Question 14 Name the enzyme secreted by the stomach.
Answer: Pepsin

Question 15 Name the largest gland of human body which is composed of densely packed tissues.
Answer: Liver

Question 16 Name the largest digestive gland of our body.
Answer: Liver

Question 17 Name one mixed gland.
Answer: Pancreas

Question 18 From which digestive gland trypsin is secreted?
Answer: Pancreas

Question 19 Insulin hormone is secreted from which gland?
Answer: Pancreas

Question 20 Which digestive juice neutralises the HCI secreted by stomach?
Answer: Pancreatic juice

Question 21 Name the largest lymphoid gland of human body.
Answer: Spleen

Question 22 Which organ removes dead RBCs from blood?
Answer: Spleen removes dead RBCs from the blood.

Question 23 Name one gland in human body that secretes digestive enzymes along with hormones.
Answer: Pancreas

Question 24 Which two organs of our body contract and expand continuously throughout our lives?
Answer: Heart and lungs

Question 25 Name the paired organs which are protected by rib bones from all sides.
Answer: The lungs are the paired organs which are protected by rib bones from all sides.

WBBSE Class 9 Life Science Question And Answer

Question 26 Name the outer membrane of lungs.
Answer: Pleura

Question 27 Name the organ of our body, through which blood passes along two different paths.
Answer: Heart is the organ of our body, through which blood passes along two different paths.

Question 28 What do you mean by pericardium?
Answer: The heart remains surrounded by a double layered transparent sac called pericardium.
It protects the heart from mechanical friction with the adjoining structures.

Question 29 Which organ of our body remains protected in a roundish bony case known as cranium?
Answer: Brain

Question 30 Which organ transmits messages in form of impulses?
Answer: Brain

Question 31 This elongated cord-like structure acts as the centre for reflex action of our body. What is it?
Answer: Spinal cord

Question 32 Name the cells from which testosterone is secreted inside the testes of male.
Answer: Leydig cells

Question 33 Name two hormones secreted by the corpus luteum in females.
Answer: Oestrogen and progesterone

Question 34 What is the process of production of ovum called?
Answer: Oogenesis

Question 35 Name two hormones influencing secretion of oestrogen.
Answer: FSH (Follicle Stimulating Hormone) and LH (Luteinizing Hormone)

Question 36 Which paired structures keep our blood clean from metabolic wastes?
Answer: The kidneys keep our blood clean from metabolic wastes.

Question 37 In which organ ammonia is converted to urea?
Answer: Liver

Question 38 Name the chief excretory product of human.
Answer: Urea

Question 39 Renin and erythropoietin are released from which organ?
Answer: Kidney

WBBSE Class 9 Life Science Question And Answer

Chapter 2 Levels Of Organization Of Life Major Organs Of The Human Body And Their Function Fill in the blanks

Peritoneum is the membrane, lining the cavity of the abdomen and covering the abdominal organs.

Stomach helps in the partial digestion of protein, by secreting Pepsin

Contraction of the heart is known as Systole

There are Four chambers in the human heart.

1. Toxic wastes of the human body are filtered out by Kidney
2. The main organ of the circulatory system is Heart
3. Cranium is the protective covering of the human brain.
4. The process of production of spermatozoa is known as Spermatogenesis
5. Skin is the outer covering of the human body.
6. Tears contain lysozyme to destroy bacterial cell walls.
7. HCl is secreted by the Oxyntic or parietal cell of the stomach.
8. Lungs are located in the thoracic cavity above the diaphragm.
9. Structural unit of the lungs is Alveoli
10. Thoracic cage is made up of 12 pairs of Ribs
11. Spleen is situated in the left hypochondrium directly beneath the diaphragm.
12. Spleen engulfs bacteria and foreign particles in the blood.
13. Kidney is situated below the membrane called the Peritoneum membrane.
14. Bile is stored in Gall’s bladder
15. Ovary produces ovum.

Chapter 2 Levels Of Organization Of Life Major Organs Of The Human Body And Their Function State True Or False

Question 1. Sweat helps to kill bacteria.

Answer: True

Question 2. The pigment which gives color to the skin is melatonin.

Answer: False

Question 3 Skin is involved in the synthesis of vitamin D.

Answer: True

Question 4. The liver secretes bile.

Answer: True

WBBSE Class 9 Life Science Question Answer

Question 5 Spleen is an organ, where the formation and destruction of RBC occurs.

Answer: False

Question 6. The spleen controls the metabolism of carbohydrates, proteins, and fats.

Answer: False

Question 7. All emotions are the sensory information in the brain.

Answer: False

Question 8. Only the brain makes the central nervous system.

Answer: False

Question 9. The human heart drives oxygenated blood from the left ventricle to the body, through pulmonary circulation.

Answer: False

Question 10. The heart is an organ of the circulatory system.

Answer: True

Question 11. The kidney is held at the back wall of the abdominal cavity.

Answer: True

WBBSE Class 9 Life Science Question And Answer

Question 12. The kidney is a rod-shaped structure.

Answer: False

Question 13. The functional unit of the kidney is the neuron.

Answer: False

Question 14. Urea is produced in the kidneys.

Answer: False

Question 15. Diaphragm is present between the thoracic and abdominal cavities.

Answer: True

Chapter 2 Levels Of Organization Of Life Major Organs Of The Human Body And Their Function Match The Columns

Answer: 1-C; 2-A; 3-D; 4-E

Answer: 1-B; 2-A; 3-E; 4-C

Answer: 1-D; 2-E; 3-A; 4-B

Answer: 1-B; 2-A; 3-D; 4-C

Chapter 2 Levels Of Organization Of Life Major Organs Of The Human Body And Their Function Find The Odd One Out

Question 1. Sweat, Pepsin, Lipase, HCl
Answer: Sweat

Question 2. Nephron, Neurone, Alveoli, Skin
Answer: Skin

Question 3. O2 transport, CO2 release, Pleura, Alveoli
Answer: O2 transport

Question 4. Ribosome, Mitochondria, Pancreatic, amylase, Lysosome
Answer: Pancreatic amylase

WBBSE Class 9 Life Science Question And Answer

Question 5. Pancreas, Digestive juice, Testis, Ovary
Answer: Digestive juice

Question 6. Insulin,Testosterone,Progesterone, Oestrogen
Answer: Insulin

Question 7. Interstitial cells of Leydig, Sertoli cells, Islets of Langerhans, Spleen
Answer: Spleen

Question 8. Nerve, Brain, Spinal cord, Spleen
Answer: Spleen

Question 9. Pleura, Myocardium, Diaphragm, Liver
Answer: Liver

Question 10. Urea, Creatinine, Ammonia, Sperm
Answer: Sperm

Chapter 2 Levels Of Organization Of Life Major Organs Of The Human Body And Their Function Fill In The Blanks By Looking At The First Pair

1. O₂-CO₂, transport: Heart:: O₂-CO₂, exchange: Lungs

2. Kidney: Nephron:: Lung: Alveoli

3. Contraction and relaxation of Lungs::Diaphragm:: Contraction and relaxation of Heart: Myocardium

4. Carbohydrate metabolism Liver:: RBC storage: Spleen

5. Ionic balance: Kidney:: Immunity: Spleen

6. Circulation: Heart:: Excretion: Kidney

WBBSE Class 9 Life Science Question Answer

7. Memory: Brain:: Reflex action: Spinal cord

8. Body balance maintenance: Cerebellum:: Control reflex action: Testosterone

9. Ovary: Oestrogen:: Testis: Spinal cord

Chapter 2 Levels Of Organization Of Life Major Organs Of The Human Body And Their Function Among The Four Concepts Given, Three Of Them Belong To One. Find That

Question 1 Stomach, Peptic cell, Gastric Juice, HCl
Answer: Stomach

Question 2 Intelligence, Thoughts, Memory, Brain
Answer: Brain

Question 3 HCI secretion by the stomach, Protective power of body, Lysozyme secretion by sweat gland, Engulfing of bacteria by spleen
Answer: Protective power of the body

Question 4 Endocrine function, Testis, Ovary, Pancreas
Answer: Excretion

Question 5 Pancreas, Testis, Mixed gland, Ovary
Answer: Mixed Gland

Question 6 Leydig cells, Testis, Testosterone, Sperm production
Answer: Testis

Question 7 Corpus luteum, Ovary, Progesterone, Relaxin
Answer: Ovary