Chapter 2 Levels Of Organization Of Life Organic And Inorganic Molecules Summary Long Answer Type Questions
Question 1. Schematically represent the list of molecules, which are important for life.
Answer:
Important molecules of life
WBBSE Class 9 Life Science Solutions
Question 2. Briefly describe the roles of water in living organisms. Mention the importance of different gases and salts in living organisms.
Answer:
Roles of water in living organisms:
1. The body of a living organism consists of 70-90% water.
2. Water acts as the medium of all cellular reactions within protoplasm.
3. In plants, water helps in many physiological processes, like photosynthesis, the ascent of sap, germination of seeds, and transpiration.
4. In animals, water is the major component of body fluid.
It maintains salt and water balance and helps in the processes of digestion, excretion, etc.
5. In starfish sea urchins and other echinoderms, water helps in locomotion also.
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Importance of different gases in living organisms
Oxygen and carbon dioxide are the two most biologically important gases.
Their importance is as follows-
1. Oxygen is essential for respiration in all aerobic organisms. It helps to oxidize food and liberate energy.
2. Carbon, which is the raw material of photosynthesis, is obtained by autotrophs in the form of carbon dioxide.
Importance of salts in living organisms:
1. Salts maintain osmoregulation in the body of living organisms.
2. Salts control the production of thyroid hormones.
3. Salts help to form the structure of bones.
3 What is a carbohydrate? Classify carbohydrates according to their structure.
Answer:
Carbohydrate
A carbohydrate is a biomolecule, made up of carbon, hydrogen, and oxygen, where hydrogen and oxygen usually maintain a ratio of 2:1.
Organisms break down carbohydrates to produce energy for cellular processes.
The general formula of carbohydrate is Cn(H2O)n.
Classification of carbohydrates:
Structurally carbohydrates are of four types.
These are-
1. Monosaccharides:
Monosaccharides are the simplest form of carbohydrates that do not hydrolyze further into smaller units.
Example Glucose, fructose, galactose, etc.
2 Oligosaccharides:
Oligosaccharides are the type of carbohydrates, which are composed of 2-9 molecules of monosaccharides, joined by glycosidic bonds.
According to the number of molecules of monosaccharides present, oligosaccharides can be classified into disaccharides, trisaccharides, tetrasaccharides, pentasaccharides, etc.
Examples are Sucrose (disaccharide), raffinose (trisaccharide), stachyose (tetrasaccharide), verbascose (pentasaccharide), etc.
3 Polysaccharides:
Polysaccharides are composed of ten to numerous molecules of monosaccharides.
Example-Cellulose, glycogen, inulin, dextrin, starch, etc.
Question 4. Briefly mention the main characteristic features of carbohydrates and their importance in the living body.
Answer:
Main characteristic features of carbohydrates:
1. Carbohydrates are colorless, odorless, and mostly water-soluble (polysaccharides are insoluble in water) organic compounds.
2. Smaller carbohydrates (monosaccharides and disaccharides) are sweet tasting, hence, they are known as sugars.
3. Carbohydrates behave as reducing molecules due to the presence of aldehyde and ketone in them.
4. In larger carbohydrate molecules, monosaccharide units may arrange in either a linear or circular manner.
Importance of carbohydrates in the living body:
The importance of carbohydrates in the living body is as follows-
1. Energy production:
Monosaccharides (glucose and fructose) act as fuel to fulfill the body’s energy needs.
The calorific value of carbohydrates is 4.1 kcal/g.
2 Structural function:
Structural components of cell walls, cell coats, and blood group antigens are carbohydrates.
3 Synthesis of biomolecules: Glucose and other sugars are transformed into fats and amino acids by some physiological processes.
4. Bowel formation: Most animals are incapable of digesting cellulose.
So it is accumulated in the intestine as roughage, which in turn, helps in bowel formation.
5 Brain development: Galactose, derived from milk sugar (lactose), helps in brain development in infants.
6 Prevention of ketosis: Very low intake of carbohydrates causes the breakdown of fat and production of ketone bodies.
This causes a disease called ketosis. Regular intake of carbohydrates prevents the chance of ‘ketosis.
Question 5. Describe in brief the chemical structure of carbohydrates.
Answer:
Chemical structure of the carbohydrate:
Carbohydrates are the most abundant biomolecule on earth.
1 Structural components:
Carbohydrate consists of carbon (C), hydrogen (H), and oxygen (O) atoms, usually with a ratio of 1:2:1.
2 Chemical formula:
The general formula of carbohydrates is Cn (H2O)n. For example, the formula of glucose is C6H12O6. But there are some exceptions also. Such as the chemical formula of rhamnose is C6H1205
3 Chemical group:
The basic carbohydrate molecule possesses an aldehyde or ketone group and one hydroxyl group in every carbon atom except the one involved in the carbonyl group. The chemical structure of glucose and fructose is given here.
Isomerism Glucose and fructose have the same chemical formula, but because of their different chemical structure, they possess different physical and chemical properties. This phenomenon is known as isomerism.
Question 6. Classify monosaccharides based on the number of carbon atoms. Mention the characteristic features of monosaccharides.
Answer:
Classification of monosaccharides:
Based on the number of carbon atoms, monosaccharides can be classified into the following types.
1. Triose: These monosaccharides are composed of three carbon atoms. Example- Glyceraldehyde.
2 Tetrose: These monosaccharide molecules have four carbon atoms. Example-Erythrose.
3 Pentose: Five carbon atoms are present in a pentose monosaccharide. Example-Ribose.
4. Hexose: This is the most commonly occurring monosaccharide, which is composed of six carbon atoms. Example-Glucose, fructose, etc.
5 Heptose: Few monosaccharides are of this type, which has seven carbon atoms.
Example: Sedoheptulose.
Characteristic features of monosaccharides:
The characteristic features of monosaccharides are as follows
1. These are crystalline solids at room temperature and are quite soluble in water. Monosaccharides are colorless, sweet substances.
2. These are reducing sugars, and reducing mild oxidizing agents because they have free ketone or aldehyde groups.
3. These produce glycoside bonds when reacting with alcohol and form enediol compounds when reacting with base.
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Question 7. What Is amino acid? Mention the functions of amino acids.?
Solution:
Amino acid:
The organic compounds, composed of at least one amino group (-NH2) and one carboxyl group (-COOH), are called amino acids.
In an amino acid molecule, a central carbon atom remains attached with one amino group, one carboxyl group, one hydrogen atom, and one variable group Amino (R). Amino acids act as the structural unit of proteins.
Examples: Methionine, alanine, etc.
Functions of amino acid
Structural function:
Amino acids take part in the formation of protoplasm and different structural proteins, like keratin, elastin, etc. in living organisms.
2 Controlling of biochemical reactions:
Amino acids play an important role in enzyme formation, which controls various biochemical reactions in our body.
3 Haemoglobin formation:
Certain amino acids and iron atoms unite to form hemoglobin which is the oxygen and carbon dioxide transporting metalloprotein of blood.
4 Hormone production:
Certain amino acids unite to produce proteinaceous hormones, like ACTH, insulin, etc.
5 Antibody formation:
Some amino acids take part in antibody formation and thus help in developing immunity.
6 Nitrogen storage:
Amino acids store nitrogen in the form of amides.
7. Neoglucogenesis:
In the case of protein deficiency in the human body, amino acids produce glucose by the process of neoglucogenesis.
Question 8. Schematically represent the classification of protein.
Answer:
Classification of protein
Question 9. Mention different important functions of proteins in the human body. Write down the roles of lipids in life processes.
Answer:
Role of Proteins in the human body
1. Proteins are the building materials of a living cell.
2. Proteins are directly involved in the development of the embryo, growth, healing of wounds, repair of damaged tissues, etc.
3. Proteins are the main structural components of animal cell membranes and cell organelles, different body tissues, different enzymes, hormones and antibodies, and several other substances.
4. Nucleoproteins constitute chromosomes, which carry genes.
5. Protein is also a major source of energy. The calorific value of protein is 4.1 kcal/g.
6. Broken non-nitrogenous amino acids produce carbohydrates and fats through the process of deamination and transamination.
7. Proteins act as a buffer solution to maintain the pH of the body.
8. In mammals, proteins play an important role in the production of milk during lactation.
Roles of lipids in life processes:
The roles of lipids in life processes are as follows-
1. Lipids act as the reserve food materials of plants and animals.
2. Fat can generate maximum heat energy. Its calorific value is 9.3 kcal/g. Animals like frogs, snake, etc. store fat in the adipose cells under their skin, which protect them against extreme cold.
3. Fat deposits in the body of desert animals (such as camels) are oxidized to produce metabolic water, to counter extreme dryness.
Question 10. Give a brief account of different proteins based on their nutritional value along with their sources.
Answer:
Different proteins based on nutritional value:
The nutritional value of proteins depends upon the number of essential amino acids present in it.
1. First-class proteins:
The proteins which contain all essential amino acids in such a proportion that is necessary for building our body, are treated as first class proteins.
Sources-Different animal proteins like milk, meat, fish, egg, etc.
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2 Second class proteins:
The proteins which may contain essential amino acids but not in such a proportion, that is necessary for building the body, or lack a few essential amino acids, are known as second-class proteins.
Sources-Pulses, gram, rice, wheat, etc.
3 Third class proteins: These proteins do not contain essential amino acids, hence, play no role as body building material, these are merely catabolised to generate heat.
Source-Gelatin.
Question 11. Mention two biological importance of fatty acids. Mention the role of essential fatty acids in our body.
Answer:
Importance of fatty acids
Two biological importance of fatty acids are as follows:
1. Fatty acids are the units of fat, which is one of the most important structural components of the body.
2. Products of many fatty acids act as hormones.
Role of essential fatty acids:
The role of essential fatty acids in our body is mentioned below.
1. Essential fatty acids are responsible for keeping the skin glowing and wrinkle-free.
2. These help in maintaining the membrane permeability of skin cells.
3. These help in maintaining a steady supply of milk in the mammary glands of lactating mothers.
4. Essential fatty acids help to maintain water balance in the body.
5. These fatty acids help in growth and extend reproductive life.
6. These help in transporting cholesterol in the blood.
7. Function of the kidney is further supported due to the presence of some essential fatty acids.
Question 12. Describe the structure of a nucleotide and explain different structural components of nuclotide with schematic diagram. Mention the main roles of nucleotides in life processes.
Answer:
Structure of nucleotide:
Nucleotides are the units of nucleic acids. Several Phosphate group nucleotide monomers join in a linear sequence to constitute a nucleic acid molecule. A nucleotide is composed of three components-
1. A pentose (5C) sugar
2. A nitrogenous base
3. A phosphate group. A nucleotide monomer without phosphate is called a nucleoside. Practically, A phosphate group holds two successive nucleosides together.
Nucleotides have two basic types of nitrogenous bases:
1. Purines (including adenine and guanine),
2. Pyrimidines (include thymine, cytosine, and uracil).
Pentose sugar also of two types:
1. ribose
2. deoxyribose.
Schematic representation of different structural components of a nucleotide
Roles of nucleotides in life processes:
The main roles of nucleotides in life processes are as follows:
1. Nucleotides play an important role in cell signaling and metabolism.
2. The specific arrangement of nucleotides on a nucleic acid stores genetic information for performing all the biochemical activities in all living organisms.
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Question 13. Mention the types of nucleotides.
Answer:
Types of nucleotides:
Nucleotides are composed of pentose sugar, nitrogen bases, and phosphoric acid. The variation in the constituting ribose sugar and nitrogen bases causes the formation of different types of nucleotides.
1. Based on pentose sugar:
The pentose sugar, present within nucleotide, can be either ribose sugar or deoxyribose sugar. According to this, the nucleotides are termed ribonucleotide or deoxyribonucleotide respectively.
2 Based on nitrogen bases:
1. Based on nitrogenous bases, deoxyribonucleotides can be divided into four groups- dATP, dGTP, dTTP, and dCTP. A deoxyribonucleotide that is composed of one Adenine base, one Deoxyribose sugar, and a phosphate radical is called dATP or deoxyadenosine triphosphate.
Similarly, guanine, thymine, and cytosine-containing deoxyribonucleotides are known as dGTP or deoxyguanosine triphosphate, dTTP or deoxythymine triphosphate and dCTP or deoxycytidine triphosphate respectively.
2. Ribonucleotides act as structural units of RNA molecules. Similarly, ribonucleotides are also of four types. As ATP or adenosine triphosphate, GTP or guanosine triphosphate, UTP or uracil triphosphate, and CTP or cytosine triphosphate.
Question 14. What is nucleic acid? Schematically describe the classification of nucleic acid.
Answer:
Nucleic acid:
The biological macromolecules, which are the polymers of nucleotides, present in all living cells and responsible for determining and regulating the genetic characteristics of an organism, are known as nucleic acid.
Example: Deoxyribonucleic acid [DNA] and ribonucleic acid [RNA]
Question 15. Write down the structure of the RNA molecule. Describe the function of RNA molecules.
Answer:
Structure of RNA molecule
1. ORNA is a single-stranded polymer of ribonucleotides.
2. RNA is composed of five carbon containing ribose sugar, nitrogen bases, and a phosphate group.
3. The nitrogenous bases present in RNA are adenine [A], guanine [G], uracil [U], and cytosine [C].
4. RNA molecules may fold upon themselves to form a complex structure.
The function of RNA molecule
1. All physiological functions of the body of an organism are regulated by proteins. mRNA molecule is responsible for the synthesis of protein molecules. rRNA and tRNA also help in protein synthesis.
2. In RNA virus, RNA acts as its genetic material and is transmitted during its replication.
Index:
A = Adenine, G = Guanine
C=Cytosine, U = Uracil
Structure of RNA
Question 16. Schematically represent the different components of a DNA molecule. Briefly describe the structure of a DNA molecule.
Answer:
Components of a DNA molecule
Structure of a DNA molecule:
A DNA molecule is a double-stranded, coiled, helical structure, running in opposite directions and made up of several nucleotide units. Many nucleotide monomers join in a linear sequence in two parallel strands to constitute a DNA molecule. The structural unit of DNA is composed of a sequence of deoxyribonucleotides.
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Such a nucleotide is composed of three components:
1. A five-carbon containing deoxyribose sugar,
2. Any one of the four nitrogenous bases (viz. adenine, guanine, thymine, and cytosine)
3. A phosphate group. Practically, two successive nucleosides are held Adenine Thymine together by a phosphate group to constitute a DNA strand. The two strands of a DNA molecule are zipped together by weak hydrogen bonds.
Here, adenine joins with thymine by two hydrogen bonds (A = T) and guanine joins with cytosine by three hydrogen bonds (G ≡ C).
Question 17. Mention the similarities and dissimilarities of DNA and RNA.
Answer:
Similarities between DNA and RNA
The similarities between DNA and RNA are as follows:
1. Both DNA and RNA are nucleic acids.
2. Both are made up of pentose sugar, nitrogenous base, and phosphate.
3. Both are treated as bio-macromolecules.
4. DNA and RNA carry the same types of purines, i.e. adenine and guanine.
5. Cytosine is present in both these molecules.
Dissimilarities between DNA and RNA:
Chapter 2 Levels Of Organization Of Life Organic And Inorganic Molecules
Long Answer Type Questions
Question 1. What is meant by vitamin? Schematically mention different types of vitamins.
Vitamin
The special component of food, which are present in very little quantities, but perform an elementary role in various physiological activities and help in developing immunity against different diseases are known as vitamins.
Different types of vitamins
Based on solubility vitamins can be divided into two types.
These are:
1. Fat-soluble vitamins – vitamins A, D, E, and K.
2. Water soluble vitamins – vitamin B complex, C and P.
Question 2. Mention some important features of vitamins.
Some important features of vitamin
1. Synthesis:
Most of the vitamins are synthesized in the plant body. A few are synthesized in the animal body (such as Vitamin A, D, K, and B12).
2. Daily requirement:
Vitamins act in very little quantities; therefore, the daily requirement of vitamins is very low.
3. Storage:
Vitamins are stored in very little quantity. Fat-soluble vitamins are stored in adipose tissue below the skin. Vitamin C is stored in the adrenal cortex.
4. Fate:
Vitamins are not digested. These are absorbed intact. However, during metabolic processes, these are partially denatured.
5. Solubility:
Some vitamins like vitamins B and C are soluble in water. Vitamins A, D, E, and K are soluble in fat and organic solvents, like ether, chloroform, etc.
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6. Help in enzymatic activity:
Some vitamins act as coenzymes and thus play an important role in enzymatic activity.
7. Role in metabolic reaction:
The requirement for vitamins is directly proportional to metabolic rate. Therefore, the daily requirement of vitamins for a physically active person or a pregnant woman is higher than for a normal person.
Question 3. Write down the names, sources, and roles of different fat-soluble vitamins in the human body.
Answer:
Names, sources, and roles of different fat-soluble vitamins in the human body
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Question 4. Mention the chemical names and deficiency diseases of different fat-soluble vitamins.
Answer:
Names and deficiency diseases of fat-soluble vitamins
Question 5. Mention names, sources, and functions of different minerals important for the human body.
Answer:
Names, sources, and functions of different minerals important for the human body
Question 6. Mention chemical names of different water-soluble vitamins and their deficiency diseases.
Answer:
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Question 7. Differentiate between water-soluble vitamins and fat-soluble vitamins.
Answer:
Differences between water-soluble vitamins and fat-soluble vitamins
Question 8. Based on physiological function classify different minerals.
Answer:
Classification of minerals based on physiological function
Based on physiological function, minerals can be classified into six types:
1. Body-forming minerals:
Calcium, phosphorus, and magnesium play vital roles in the formation of bones and teeth.
2. Body fluid regulating minerals:
Sodium, potassium, chlorine, etc., control the volume of blood, tissue fluids, cerebrospinal fluid, and cytoplasm.
3. Transporting minerals:
Certain minerals like iron, copper, etc., help in transportation. Iron takes part in the formation of hemoglobin which carries oxygen and carbon dioxide.
4. Minerals regulating enzymatic activity:
Calcium, magnesium, and iron regulate the functioning of different enzymes.
5. Hormone synthesizing minerals:
Iodine directly takes part in the synthesis of thyroxine hormone.
6. Vitamin synthesizing minerals:
Cobalt takes part in the synthesis of vitamin B12
Question 9. Mention names, sources, and functions of different minerals important for the human body.
Answer:
Names, sources, and functions of different minerals important for the human body
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Question 10. What do you understand by the terms macro-elements and micro-elements? Mention general role of different minerals on physiological processes in the human body.
Answer:
Macro-elements
The elements, which are required in large quantities for proper growth and development of the human body, are known as macro-elements.
Examples: Sodium (Na), potassium (K), chlorine (CI), calcium (Ca), phosphorus (P), etc.
Micro-elements
The elements, which are required in minute quantities for proper growth and development of the human body, are known as micro-elements.
Examples: Iron (Fe), boron (B), iodine (I), molybdenum (Mo), zinc (Zn), manganese (Mn), copper (Cu), etc.
The general role of different minerals on physiological processes in the human body
Different minerals play different roles in physiological processes in the human body, which are as follows:
1. As cofactors of enzymes:
Different minerals like iron, copper, manganese, zinc, etc., act as cofactors of different enzymes.
2. Maintenance of acid-base balance:
Certain elements like sodium, potassium, chlorine, etc., maintain acid-base balance within the body.
3. Maintenance of water balance:
Sodium helps in maintaining water balance within the body.
4. Conduction of nerve impulse:
Sodium and potassium play a very important role in the conduction of nerve impulses.
5. Control membrane permeability:
Elements like calcium and potassium control the membrane permeability of our body.
6. Role in blood coagulation:
Calcium acts as an essential blood-coagulating factor.
7. Formation of skeletal structure:
Calcium and phosphorus are the main building components of bones and teeth.