Detailed explanations in West Bengal Board Class 9 Life Science Book Solutions Chapter 2.1 Classification of Kingdom Animalia offer valuable context and analysis.
WBBSE Class 9 Science Chapter 2.1 Question Answer – Biomolecules and their Behaviour
Very Short Questions and Answers : (1 mark for each question)
Question 1.
What are we made up of?
Answer:
We are made up of millions of inorganic and organic molecules.
Question 2.
How do we denote the large molecules of the body of an organism?
Answer:
We denote the large molecules of the body of an organism as macromolecules.
Question 3.
How do we denote the elements, which we need in a very little quantity?
Answer:
The elements that are required in very little quantity in the body of an organism are denoted as micromolecules.
Question 4.
Which simple compound does a living cell need the most, for survival?
Answer:
Water is a simple compound, which a living cell needs the most, for its survival.
Question 5.
What are biomolecules?
Answer:
Biomolecules are the organic molecules produced or involved in various biochemical reactions within the cells or inside the body.
Question 6.
Which inorganic acid plays a very important role in our digestion process?
Answer:
Hydrochloric acid is the inorganic acid, which plays an important role in our digestion process.
Question 7.
What does carbonic acid do in our body?
Answer:
Carbonic acid is involved in the transportation of CO2, out of the body, via respiratory exchange of gases.
Question 8.
Which gas is involved in energy generation in a living body?
Answer:
Oxygen is involved in the energy generation in a living body.
Question 9.
Which anabolic process needs CO2?
Answer:
Photosynthesis is the anabolic process, which needs CO2.
Question 10.
Which is the most abundant salt in our body?
Answer:
Sodium chloride (NaCl) is the most abundant salt in our body.
Question 11.
Which two elements are essential for our skeletal system?
Answer:
Calcium and phosphorus are the two elements essential for our skeletal system.
Question 12.
What is the similarity among monosaccharides, amino acids and fatty acids?
Answer:
Monosaccharides, amino acids and fatty acids are all organic micromolecules.
Question 13.
What is the basic difference between nucleotides and a nucleic acid?
Answer:
Nucleotides are organic micromolecules and nucleic acid is an organic macromolecule.
Question 14.
Which type of sugars cannot be hydrolysed into smaller carbohydrates?
Answer:
Monnsaccharfths cannot be hydrolysed into smaller carbohydrates.
Question 15.
Which type of sugar is called a disaccharide?
Answer:
The sugar having two monosaccharide units is called a disaccharide.
Question 16.
How do you denote tite sugars composed of 3 to 9 monosaccharide units?
Answer:
The sugars with 3 to 9 monosaccharide units are denoted as oligosaccharides.
Question 17.
Which type of sugars is generally insoluble in water and tasteless in nature?
Answer:
Polysaccharides are generally insoluble in water and tasteless in nature.
Question 18.
What is calorltic value?
Answer:
blat heat energy liberated by the complete oxidation of Unit mass of a matter is known as its calorific value.
Question 19.
How much heat energy is liberated from one gram of glucose on its complete oxidation?
Answer:
On complete oxidation of one gram of glucose molecule, 4A kcal heat energy is liberated.
Question 20.
What is the full form of MUFA?
Answer:
The full form of MUFA is Mono Unsaturilted Fatty Acid.
Question 21.
Which type of biomolecule is commonly consumed by organisms for energy generation?
Answer:
Living organisms commonly consume carbohydrates for energy generation.
Question 22.
Which type of biomolecule is commonly consumed by organisms as body building materials?
Answer:
Living organisms commonly consume proteins as body building materials.
Question 23.
Which type of biomolecule do living organisms commonly store within the body?
Answer:
Living organisms commonly store fat within the body.
Question 24.
Which type of material in food helps in faeces formation and facilitate defecation?
Answer:
A polysaccharide, called cellulose, helps in face formation and facilitates defecation.
Question 25.
Which type of food should a growing baby be fad with?
Answer:
A Growing baby should be fed with protein-rich food for maximum muscular growth.
Question 26.
How are the two strands of a DNA molecule zipped together?
Answer:
The two strands of a DNA molecule are zipped together by weak hydrogen bonds between the bases.
Question 27.
Name the bond by which nucleosides of a nucleic acid strand remain attached one after another.
Answer:
The nucleosides of a nucleic acid strand remain attached one after another by phosphate bonds.
Question 28.
Which nucleic acid is mainly involved in carrying hereditary features from parents to oftsprings?
Answer:
Mainly DNA is involved in carrying hereditary features from parents to offsprings.
Question 29.
Which type of organisms synthesise most of the vitamins?
Answer:
Green plants synthesise most of the vitamins.
Question 30.
Which vitamin is synthesised within our skin on exposure to sun?
Answer:
Vitamin D is synthesised within our skin on exposure to sun.
Question 31.
Which type of vitamin should a person take in for problems with vision after sunset?
Answer:
A person having problems with vision after sunset should take vitamin A.
Question 32.
Give an example of an aldose sugar.
Answer:
Glucose is an example of aldose sugar.
Question 33.
Which two elements are essential for neural transport?
Answer:
Sodium and potassium are necessary for neural transport.
Question 34.
Which two simplest molecular units form a lipid molecule?
Answer:
Fatty acid and glycerol are the two simplest molecular units, which form a lipid molecule.
Question 35.
Name a reducing sugar.
Answer:
Glucose is a reducing sugar.
Question 36.
Name a non-reducing sugar.
Answer:
Sucrose is a non-reducing sugar.
Question 37.
Name two fat soluble vitamins present in egg.
Answer:
Vitamin A and vitamin D are two fat soluble vitamins present in egg.
Question 38.
Which mineral is essential for haemoglobin formation?
Answer:
Iron is essential for haemoglobin formation.
Question 39.
Which element is involved in the formation of thyroxin hormone?
Answer:
Iodine is involved in the formation of thyroxine hormone.
Question 40.
Name a mineral essential for muscle contraction and blood coagulation.
Answer:
Calcium is essential for muscle contraction and blood coagulation.
Question 41.
What is the ratio of hydrogen and oxygen in carbohydrates?
Answer:
In carbohydrates, hydrogen and oxygen are present in the ratio of 2: 1.
Question 42.
Give an example of a ketohexose.
Answer:
Fructose is an example of a ketohexose.
Question 43.
Name a basic protein.
Answer:
Histone is a basic protein.
Question 44.
What is the chemical name of vitamin P?
Answer:
Chemical name of vitamin P is citrine.
Question 45.
Name an iron-containing enzyme.
Answer:
Catalase is an iron-containing enzyme.
Question 46.
Name two triose sugars.
Answer:
Two triose sugars are monotriose and dihydroxyacetone.
Question 47.
Name the sweetest carbohydrate.
Answer:
The sweetest carbohydrate is fructose or fruit-sugar.
Question 48.
In animal body, fat is stored in which tissue?
Answer:
In animal body, fat is stored in adipose tissue.
Question 49.
Which disease is caused in children due to deficiency of iodine?
Answer:
Cretinism is caused in children, due to deficiency of iodine.
Question 50.
Name two vitamins present in lemon.
Answer:
Vitamin C (ascorbic acid) and vitamin P (citrine) are two vitamins present in lemon.
Question 51.
What is the chemical name of vitamin D?
Answer:
Chemical name of vitamin D is calciferol.
Question 52.
Deficiency of which vitamin results in teeth and gum deformity?
Answer:
Deficiency of vitamin C results in deformity of teeth and gums.
Question 53.
What is the minimum number of monosaccharides required to form a polysaccharide?
Answer:
At least 10 monosaccharide molecules are necessary to constitute a polysaccharide.
Question 54.
What is the main function of vitamin A in human?
Answer:
Vitamin A helps in the production of rhodopsin pigment in rod cells of human eye.
Question 55.
What is meant by a polypeptide?
Answer:
Large polymers of numerous amino acid molecules, linked together by peptide bonds, are known as polypeptides.
Short Questions and Answers : (2 marks for each question)
Question 1.
Schematically represent the molecules of life.
Answer:
Molecules of life are mentioned in the following chart-
Question 2.
Why are different molecules so important for our existence?
Answer:
Life has originated from different non-living molecules through complex chemical reactions. These molecules build our body as well as help to maintain all our life processes. That is why, these are important for our existence.
Question 3.
Mention the roles of two biologically important gases, which organisms absorb directly from atmosphere.
Answer:
Oxygen and carbon dioxide are the two biologically important gases, which organisms absorb directly from atmosphere. All aerobic organisms utilise oxygen to oxidise glucose and liberate energy, necessary to run their life processes. All autotrophs use carbon dioxide as the raw material for photosynthesis to prepare their food.
Question 4.
Mention the roles of an acid and a base in human body.
Answer:
Hydrochloric acid, secreted in stomach, converts pepsinogen into active pepsin to start digestion of protein, HCl also helps to hydrolyse sucrose. Sodium bicarbonate, present in bile, is basic in nature, which neutralises the acidic contents of stomach as soon as it reaches the duodenum.
Question 5.
Classify biomolecules based on their molecular weight and give two examples for each.
Answer:
On the basis of molecular weight, organic molecules or biomolecules can be differentiated into two basic types. These are – bio-micromolecules and bio-macromolecules. Examples of bio-micromolecules are mono-saccharides, amino acids etc. Examples of bio-macromolecules are proteins, nucleic acids etc.
Question 6.
What is meant by carbohydrates? Give two examples.
Answer:
Carbohydrates are the organic compounds made up of carbon, hydrogen and oxygen, in which hydrogen and oxygen maintain a ratio of 2:1. Examples — Glucose and cellulose.
Question 7.
Why are carbohydrates called saccharides? Give any two examples of two different types of saccharides.
Answer:
Naturally occurring carbohydrates or the end products of their hydrolysis are sweet to taste. In Greek, ‘saccharides’ means sugars, therefore, carbohydrates are commonly called saccharides. Saccharides are of different types – mono, oligo and polysaccharides. Two example of monosaccharides are glucose and fructose and two examples of oligosaccharides are sucrose and raffinose.
Question 8.
Mention plant and animal carbohydrates.
Answer:
Carbohydrates are mostly found in different plant products – rice, wheat, maize, potato, beet, arum are the sources of starch. Various fruits like mango, banana, oranges etc. provide fructose. Juice of date-palm plant, sugarcane are rich in sucrose and glucose. All green vegetables and some fruits, like wood apple, water melon etc. are good sources of cellulose. Milk is an animal product that contains milk sugar (lactose).
Question 9.
what is meant by sugars? Give example of two biologically important sugars.
Answer:
Carbohydrates with low molecular weight, high water solubility and sweet taste are called sugars.
Example -Two biologically important sugars are glucose and fructose.
Question 10.
What is glycosidic bond?
Answer:
The bond that develops between two or more monosaccharide units to form disaccharide, oligosaccharide or polysaccharide molecules is known as glycosidic bond.
Question 11.
What is meant by monosaccharides? Mention the basic molecular formula of monosaccharides.
Answer:
- Monosaccharides: Monosaccharides are the simplest form of carbohydrates, which have low molecular weight, high water solubility, sweet taste and cannot be hydrolysed further into smaller carbohydrates. Fructose is one type of monosaccharide.
- Molecular formula: The basic molecular formula of carbohydrate is (CH2O)n.
Question 12
What is meant by disaccharides? Give two examples of biologically important disaccharides.
Answer:
Disaccharides are the sweet tasting, watersoluble carbohydrates, composed of two monosaccharide molecules. Examples-Sucrose and lactose are the two biologically important disaccharides.
Question 13.
What are oligosaccharides? Mention the basic molecular formula of oligosaccharides.
Answer:
- Oligosaccharides: Oligosaccharides are the complex type of carbohydrates, which are composed of 3 to 9 monosaccharide units. Example-Raffinose.
- Molecular formula: The basic molecular formula of oligosaccharides is Cn(H2O)n-1
Question 14.
What are polysaccharides? Mention the basic molecular formula of polysaccharides.
Answer:
Polysaccharides: Polysaccharides are water insoluble and tasteless type of complex carbohydrates, composed of ten to numerous monosaccharide units. Example-Cellulose.
Molecular formula: The basic molecular formula is (C6H10O5)n
Question 15
Why carbohydrates are called ‘protein sparing food’?
Answer:
By consuming adequate carbohydrates, an organism can survive without taking dietary proteins. Within the body, these carbohydrates are transformed into amino acids by some metabolic processes. These amino acids consequently form different proteins. Therefore, carbohydrates are called ‘protein sparing food.’
Question 16
What is meant by amino acid? Give example.
Answer:
An amino acid is the structural and functional unit of a protein which is composed of carbon, hydrogen, oxygen and nitrogen, typically possessing an amino (-NH6) group and a carboxyl (-COOH) group.
Example-Glycine, Alanine, Histidine etc.
Question 17.
What is an ester?
Answer:
The organic compound, that is formed by the reaction of an alcohol and an organic acid, is called ester. Example-Glycerides phosphoester.
Question 18.
What are proteins? Give example.
Answer:
Proteins are biologically important macromolecules, composed of either a number of amino acids or a combination of amino acids and few non-amino acid components, acting as the building materials of all living bodies. Example – Albumin, Globulin, Haemoglobin etc.
Question 19.
Mention two characteristic features of proteins.
Answer:
Two characteristic features of proteins are as follows-
- Proteins are polymers of amino acids which are basically composed of carbon, hydrogen, oxygen and nitrogen.
- Proteins are mostly soluble in water and they coagulate on heating.
Question 20.
What is meant by simple proteins? Give example.
Answer:
The proteins, which do not contain anything other than amino acids, joined by peptide bonds, are known as simple proteins. Example – Albumin, Globulin, Glutenin etc.
Question 21.
What is meant by conjugated proteins? Give example.
Answer:
The proteins which are composed of amino acids and some non-amino acid components, are called conjugated proteins. Example – Haemoglobin, Haemocyanin, Cytochrome etc.
Question 22
What is meant by derived proteins?
Answer:
Certain proteins are produced during the hydrolytic breakdown of larger protein molecules. These are called derived proteins. Example – Peptone, Metaprotein, Proteose etc.
Question 23.
What is meant by basic amino acids? Give example.
Answer:
The amino acids which have two or more basic amino groups (-NH2), are called basic amino acids.
Example – Lysine, Arginine, Histidine etc.
Question 24.
What is meant by acidic amino acids? Give example.
Answer:
The amino acids which have two or more acidic carboxyl groups (-COOH), are called acidic amino acids. Example – Glutamic acid, Aspartic acid etc.
Question 25.
What is meant by essential amino acids? Give example.
Answer:
The acids, which are indispensable for normal growth and development, but are not synthesised within the body and can only be taken in as food, are known as essential amino acids.
Example: Tryptophan, Phenylalanine, Threonine, Valine, Methionine, Leucine, Isoleucine.
Question 26
Mention the sources of proteins.
Answer:
Proteins are available in both animal and plant products. Animal sources of proteins are fish, meat, egg and milk. Among plant sources, pulses, soyabean, gram etc. are rich in proteins. Rice, wheat, certain fruits and vegetables also contain a little bit of protein.
Question 27.
Mention the importance of protein in human body.
Answer:
Protein is the building block of our body. For this reason, the body needs adequate supply of proteins through food. Deficiency of protein may lead to retardation of physical as well as mental growth. Development of brain, eye, bones and muscles will be affected the most. Several physiological activities are also hampered due to protein deficiency.
Question 28.
Mention two diseases caused due to protein malnutrition.
Answer:
Marasmus and Kwashiorkor are two commonly known diseases which are caused due to protein malnutrition.
Question 29.
What is meant by fatty acids? Give example.
Answer:
Fatty acids are the smaller biomolecules, composed of three elements like carbon, hydrogen and oxygen, having a hydrocarbon chain ending with a carboxyl (-COOH}) group and taking part in the formation of lipids. ExampleLanoline, Linolenic acid.
Question 30.
Why egg is called the reference protein?
Answer:
Egg contains almost all proteins in perfect proportions as per requirement of the body. Nutritionists, therefore measure the nutritional value of other proteins with reference to the proteins present in egg, so egg is known as the reference protein.
Question 31.
What is meant by saturated fatty acid?
Answer:
The fatty acids in which carbon atoms are joined to each other by monovalent bonds, are known as saturated fatty acids. ExamplePalmitic acid, Stearic acid etc.
Question 32.
What is meant by unsaturated fatty acid?
Answer:
The fatty acids in which carbon atoms are joined to each other by bivalent or trivalent bonds, are known as unsaturated fatty acids. Example-Linolenic acid, Linoleic acid etc.
Question 33.
What is meant by lipids? Mention the dietary sources of lipids.
Answer:
- Lipids: The esters of fatty acids and alcohols which are insoluble in water but soluble in organic solvents like acetone, benzene, chloroform, ether etc., are known as lipids.
- Sources of lipids: Butter, ghee, oils, coconut, different types of oil seeds, red meat are the common dietary sources of lipids.
Question 34.
What is meant by essential fatty acids?
Answer:
Certain physiologically important fatty acids are never synthesised within the body. We get it from dietary fats. These are called essential fatty acids. Example-Linolenic acid, Linoleic acid are two essential fatty acids.
Question 35.
Classify lipids. Give an example of each type.
Answer:
The following chart shows different types of lipids with one example of each.
Question 36
What is meant by simple lipids? Give example.
Answer:
The lipids which are composed of esters of different fatty acids and glycerol only, are called simple lipids. Example-Lanoline, Wax etc.
Question 37.
What is meant by conjugated lipids? Give example.
Answer
Certain types of lipids are composed of some other substances beside fatty acids and glycerol, these are called conjugated lipids. Example-Phospholipid, Glycolipid etc.
Question 38.
What is meant by derived lipids? Give example.
Answer:
Derivatives of lipids or biologically active lipid-like compounds, are called derived lipids.
Example-Prostaglandins, Steroids etc.
Question 39.
Mention the physical characteristic features of lipids.
Answer:
The physical characteristic features of lipids are as follows-
- Lipids are colourless, tasteless and odourless substances,
- Lipids are insoluble in water but soluble in organic solvents like ether, benzene, chloroform etc.
- Due to low specific gravity all lipids float in water.
Question 40.
Mention two importances of lipid in a living organism.
Answer:
Two importances of lipid in a living organism are as follows-
- Lipids are the reserve food materials of plants and animals.
- Lipid is one of the main structural components of cell membrane.
Question 41.
What is meant by fat? Give example.
Answer:
The triglycerides which remain in solid or semi-solid state at room temperature, are called fat. One example of plant fat is margarine and that of animal fat is butter.
Question 42
What is meant by wax? Give example.
Answer:
Wax is a solidified ester of a fatty acid and an alicyclic or aliphatic monohydric alcohol other than glycerol. Example-Lanoline, Bee-wax etc.
Question 43.
What is meant by organic oil? Give example.
Answer:
The glycerides which are hydrophobic, lipophilic, slippery substances, with low melting points and remain in liquid state at room temperature, are called organic oils. ExampleCoconut oil, mustard oils etc.
Question 44.
What is nucleoside?
Answer:
Nucleoside is an elementary part of a nucleic acid composed of any one of the purines or pyrimidines bases and a pentose sugar of either ribose or deoxyribose type.
Question 45
What is meant by nucleic acid? Give example.
Answer:
The largest biological macromolecule, composed of several nucleotides, occuring in all living cells for storing and transmitting hereditary characters and genetic information, is known as nucleic acid. Example-Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
Question 46
Classify different types of nitrogenous bases found in nucleic acids.
Answer:
The following chart shows different types of nitrogenous bases found in nucleic acids.
Question 47.
Where does DNA occur?
Answer:
DNA occurs inside the protein capsule of DNA-virus. In eukaryotic cells, it is present in chromosomes within the nucleus. It is also present in the matrix of their mitochondria and plastids. In prokaryotic cells, it is present as a circular DNA, but it lies naked in the cell cytoplasm in a specialised region called nucleoid.
Question 48.
Write two functions of DNA.
Answer:
Two functions of DNA are as follows-
- DNA transmits hereditary characters from parents to offspring.
- DNA controls all gene-regulated biological activities.
Question 49.
What is RNA?
Answer:
RNA is the ribose sugar containing single stranded bio-macromolecule, which acts as the genetic material in Ribovirus and helps DNA to perform its hereditary and genetic activities in eukaryotic cells as well as helps in protein synthesis.
Question 50
What are vitamins?
Answer:
Vitamins are special components of food which are present in very little quantities, but they perform an elementary role in various physiological activities and in development of immunity against different diseases. Examplesvit. A, vit. B, vit. C, vit. D, vit. K etc.
Question 51.
What is meant by anti-vitamins? Give an example.
Answer:
Certain organic compounds hinder the functions of some vitamins or denature some vitamins completely. These compounds are known as anti-vitamins. Example-Galactoflavin is an anti-vitamin, which hinders the action of vitamin B12 or riboflavin.
Question 52.
What is a pseudo-vitamin? Give an example.
Answer:
A pseudo-vitamin is a substance that has a chemical structure similar to that of a vitamin but lacks the usual physiological effects of a vitamin. Example-Methylcobalamin is the pseudovitamin of vitamin B12
Question 53.
What is a provitamin? Give an example.
Answer:
The organic compound from which vitamin is synthesised in the body of a living organism, is called a provitamin. Example-vitamin A is synthesised in the liver from the provitamin β Carotene.
Question 54.
Mention the functions of vitamin A in human body.
Answer:
The functions of vitamin A in human body are as follows-
- Vitamin A helps to maintain health of eye, tear gland and retina.
- It helps in maintaining healthy skin and muscle.
Question 55
Why vitamin A is called anti-xerophthalmic vitamin?
Answer:
Xerophthalmia is defined as the condition characterised by excessive and abnormal dryness of the eye-ball, accompanied by conjunctivities. This occurs basically due to the deficiency of vit.A. Since, vit.A prevents Xerophthalmia, therefore it is called anti-xerophthalmic vitamin.
Question 56.
Mention the functions of vitamin D in human body. Mention its sources.
Answer:
Functions:
- Vitamin D helps in the uptake of phosphorus and calcium from the intestine.
- It helps in the formation of teeth and bones.
Sources: The sources of vit.D are milk, cabbage, vegetable oil, cod liver oil etc.
Question 57.
Why vitamin D is called anti-ricketic vitamin?
Answer:
Ricket is a vit.D deficiency disease. Since vit.D helps in the prevention of the disease, therefore it is called as anti-ricketic vitamin.
Question 58.
Which vitamin is called anti-sterility vitamin? Mention the main functions of this vitamin.
Answer:
Anti-sterility vitamin: Vitamin E is called antisterility vitamin
Functions of vitamin E:
- Vitamin E helps in the development of embryo, reproductive organs and muscles.
- It helps to inhibit unwanted oxidation in the body by substances called free radicals.
Question 59
Which vitamin is called anti-haemorrhagic vitamin? Mention the functions of this vitamin.
Answer:
Anti-haemorrhagic vitamin: Vitamin K is called the anti-haemorrhagic vitamin.
Functions of vitamin K:
- Vitamin K helps in prothrombin formation and blood coagulation.
- It helps in the normal energy production in mitochondria.
Question 60
Which vitamin is called anti-scorbutic vitamin? Mention the functions of this vitamin.
Answer:
Anti-scorbutic vitamin: Vitamin C is called antiscrobutic vitamin, since it helps in preventing the disease scurvy.
Function of vitamin C:
- It protects the body against some infections like common cough and cold.
- It helps in the development of teeth and bones.
- It catalyses the metabolism of carbohydrates.
Question 61
Mention the functions of vitamin B3.
Answer:
The functions of vitamin B3 are as follows:
- It catalyses the transformation of carbohydrates to lipids.
- It helps to stimulate the central nervous system.
- It helps in cellular respiration and metabolism.
Question 62
Which two vitamins help in cellular respiration? What is the similarity between iron and vitamin B12 ?
Answer:
Both vitamin B1 and B2 help in cellular respiration.
Both iron and vitamin B12 help in the formation of red blood cells.
Question 63.
Mention one function of chlorine. Write a function of manganese.
Answer:
Function of chlorine: Chlorine helps to maintain the acid-base balance in the body.
Function of manganese: Manganese regulates the normal level of carbohydrate in the blood.
Question 64.
How do minerals control membrane permeability?
Answer:
Potassium (K) increases membrane permeability of living cells whereas calcium (Ca) restricts it. Thus, mineral elements play important role in controlling membrane permeability in the body.
Question 65
Write the names of some plant and animal sources of food which are rich in magnesium.
Answer:
- Plant sources of magnesium: The plant sources of magnesium are green vegetables, grains, groundnut, bean, soyabean, peas etc.
- Animal sources of magnesium: The animal sources of magnesium are fish, chicken, egg, milk etc.
Question 66.
Write the names of some plant and animal sources of food which are rich in iron.
Answer:
Plant sources of iron: The plant sources of iron are pulses, whole-wheat flour, spinach, lettuce, banana etc.
Aninal sources of iron: The animal sources of iron are fish, egg, mutton, liver etc.
Question 67.
Which elements and vitamins help in the formation of our skeletal structure?
Answer:
Calcium (Ca) and phosphorus (P) are the main building components of bones and teeth. Similarly, vitamin D and vitamin C are the vitamins which also help in the formation of teeth and bones. Thus, these elements and vitamins take part in the formation of the skeletal structure of the human body.
Question 68
Mention two animal sources and a plant source of calcium.
Answer:
Two animal sources of calcium are fish and egg and a plant source of calcium is peas.
Question 69
What are the functions of sodium in human body?
The functions of sodium in human body are as follows-
- It helps to maintain cardiac systole, blood pressure, blood volume and acid-base balance.
- It helps in the flow of nerve impulse.
- It also helps to maintain the density of urine.
Question 70.
Mention a plant source and an animal source of sodium.
Answer:
A plant source of sodium is vegetables and an animal source of sodium is butter.
Question 71.
Distinguish between oligosaccharides and polysaccharides.
Answer:
Features | Oligosaccharides | Polysachharides | |
1. Number of monosaccharide units | Made up of 3-9 monosaccharide units | Made up of 10 or more than 10 monosaccharide units | |
2. Solubility | Soluble in water | Insoluble in water | |
3. Taste | Sweet | Tasteless |
Question 72.
Distinguish between amino acids and fatty acids.
Answer:
Features | Amino acids | Fatty acids |
1. Occurence | Structural unit of proteins | Structural unit of lipids |
2. Chemical structure | Each molecule has one amino (-NH2) and one carboxylic (-COOH) group | Each molecule has one methyl (-CH2) and one carboxylic (-COOH) group and one intermediate ethyl (-CH2) group |
3. Function | Join with polypeptides to synthesise enzymes, hormones and to form cell components | Prepare different membranes of cell and cell organelies. Participate in lipid synthesis. |
Question 73.
Distinguish between simple carbohydrates and complex carbohydrates.
Answer:
Features | Simple carbohydrates | Complex carbohydrates |
1. Number of monosaccharide units | Made up of one or two monosaccharide units | Made up of more than two monosaccharide units |
2. Nutritional value | Quickest source of energy, lack fibre | Rich in fibre, vitamins and minerals |
3. Biological significance | Get oxidised in respiration to generate energy | Build cellular membranes and act as stored food |
Question 74.
Distinguish between nucleotides and nucleosides.
Answer:
Features | Nucleotides | Nucleosides |
1. Structural components | Pentose sugar, nitrogenous base and phosphate | Pentose sugar and nitrogenous base |
2. Nature | Acidic | Slightly basic |
3. Role | Structural unit of nucleic acids | Structural portion of a nucleotide |
Long Questions and Answers : (5 marks for each question)
Question 1.
Briefly describe the role of water in a living body. Mention the importance of different gases and salt in living organisms.
Answer:
Role of water in living body
The role of water in living body are as follows—
- Body of a living organism consists of 70-90% water. Water acts as the medium of all cellular reactions within protoplasm.
- In plants, water helps in photosynthesis, ascent of sap, germination of seeds and transpiration.
- In animals, water is the major component of body fluid. It helps in digestion, excretion and maintains salt and water balance.
- In squids and echinoderms, water helps in locomotion also.
Importance of different gases in living organisms
Oxygen and carbon dioxide are the two most biologically important gases. Their importance are as follows—
- Oxygen is essential for respiration in all aerobic organisms to oxidise food and to liberate energy.
- Carbon dioxide is the raw material, utilized by all the autotrophs for photosynthesis.
Importance of salt in living organisms
The importance of salt in living organisms are as follows—
- Salt maintains osmoregulation in body.
- Salt controls the production of thyroid hormone.
- Salt helps to form structure of bones.
Question 2.
Briefly mention the main characteristic features of carbohydrates and its importances in living body.
Answer:
Main characteristic features of carbohydrate
The main characteristic features of carbohydrates are mentioned below.
- Carbohydrates are colourless, odourless and mosdy water-soluble (polysaccharides are insoluble in water) organic compounds.
- Smaller carbohydrates (monosaccharides and disaccharides) are sweet tasting, hence, they are known as sugars.
- Carbohydrates behave as reducing molecules due to presence of aldehyde and ketone in them.
- In larger carbohydrate molecules, monosaccharide units may arrange in either linear or circular manner.
Importance of carbohydrates in living body
The importance of carbohydrates in living body are as follows —
- Monosaccharides (glucose and fructose) act as fuel to fulfill body’s energy need. Calorific value of carbohydrate is 4.1 kcal/g.
- Structural components of cell wall, cell-coat and blood group antigens are carbohydrates.
- Glucose and other sugars are transformed into fats and amino acids by some physiological processes.
- Most animals are incapable of digesting cellulose. So it is accumulated in the intestine as roughage, which in turn, helps in bowel formation.
Question 3.
Classify monosaccharides based on the number of carbon atoms. Mention the characteristic features of monosaccharides.
Classification of monosaccharides
Based on the number of carbon atoms, monosaccharides can be classified into the following types.
- Triose: These monosaccharides are composed of three carbon atoms. Example-Glyceraldehyde.
- Tetrose: These monosaccharide molecules have four carbon atoms. Example-Erythrose.
- Pentose: Five carbon atoms are present in a pentose monosaccharide. Example-Ribose.
- Hexose: This is the most commonly occuring monosaccharide, which is composed of six carbon atoms. Example-Glucose, fructose etc.
- Heptose: Few monosaccharides are of this type, which have seven carbon atoms.
Example-Sedoheptulose.
Characteristic features of monosaccharides
The characteristic features of monosaccharides are as follows-
- These are crystalline solids at room temperature and quite soluble in water. Monosaccharides are colourless, sweet substances.
- These are reducing sugars, reduces mild oxidising agents because they have free ketone or aldehyde group.
- These produce glycoside bond when react with alcohol and form enediol compound when react with base.
Question 4.
How do proteins take part in different life processes?
Answer:
Role of proteins in different life processes
Proteins take part in different life processes. These are mentioned below.
- Proteins are the building materials of a living cell.
- Proteins are directly involved in the development of embryo, growth, healing of wounds, repair of damaged tissues etc.
- Proteins are the main structural components of animal cell membrane and cell organelles, different body tissues, different enzymes, hormones and antibodies and several other substances.
- Nucleoproteins constitute chromosomes, which carry genes.
- Protein is also a major source of energy. Calorific value of protein is 4.1kcalg.
- Broken non-nitrogenous amino acids produce carbohydrates and fats by the process of deamination and trans-amination.
- Proteins act as buffer solution to maintain the pH of body.
- In mammals, proteins play important role in production of milk during lactation.
Question 5.
Schematically represent different types of proteins. Give a brief account of different proteins based on nutritional value. Mention the sources.
Answer:
Schematic representation of different types of protein
Different proteins based on nutritional value
Nutritional value of proteins depends upon the number of essential amino acids present in it.
- First class protein: The proteins which contain all essential amino acids in perfect proportion Sources of protein necessary for building our body are treated as first class proteins. Sources-Different animal proteins like milk, meat, fish, egg etc.
- Second class proteins: The proteins which may contain essential amino acids but not in perfect proportion, which 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.
- 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 6.
Mention the role of essential fatty acids in our body.
Answer:
Role of essential fatty acids
The role of essential fatty acids in our body are mentioned below.
- Essential fatty acids are responsible for keeping the skin glowing and wrinkle-free.
- These help in maintaining membrane permeability of skin cells.
- These help in maintaining steady supply of milk in mammary glands of lactating mothers.
- Essential fatty acids help to maintain water balance in the body.
- These fatty acids help in growth and extend reproductive life.
- These help in transporting cholesterol in blood.
- Function of kidney is further supported due to the presence of some essential fatty acids.
Question 7.
Mention two biological importance of fatty acids. Write down the roles of lipids in life processes.
Answer:
Importance of fatty acids
Two biological importance of fatty acids are as follows-
- Fatty acids are the units of fat, which is one of the most important structural components of the body.
- Products of many fatty acids act as hormones.
Roles of lipids in life processes
The roles of lipids in life processes are as follows-
- Lipids act as the reserve food materials of plants and animals.
- Fat can generate maximum heat energy. Its calorific value is 9.3kcalg. Animals like frogs, snake etc. store fat in the adipose cells under their skin, which protect them against extreme cold.
- Fat deposits in the body of desert animals (such as camels) are oxidised to produce metabolic water, to counter extreme dryness.
Question 8
Describe the structure of a nucleotide. Mention the main roles of nucleotides in life processes.
Answer:
Structure of nucleotide
Nucleotides are the units of nucleic acids. Several nucleotide monomers join in a linear sequence to constitute a nucleic acid molecule. A nucleotide is composed of three components-
- A pentose (5C) sugar,
- A nitrogenous base and
- A phosphate group.
A nucleotide monomer without phosphate is called nucleoside. Practically, A phosphate group holds two successive nucleosides together. Nucleotides have two basic types of nitrogenous bases-
- Purines (include adenine and guanine)
- Pyrimidines (include thymine, cytosine and uracil).
Pentose sugar is also of two types-
- ribose and
- deoxyribose.
Roles of nucleotides in life processes
The main roles of nucleotides in life processes are as follows-
- Nucleotides play an important role in cell signalling and metabolism.
- The specific arrangement of nucleotides on a nucleic acid stores genetic information for performing all the biochemical activities in all living organisms.
Question 9.
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 a 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. Such a nucleotide is composed of three components-
- A five carbon containing deoxyribose sugar,
- Any one of the four nitrogenous bases (viz. adenine, guanine, thymine and cytosine) and
- A phosphate group. Practically, two successive nucleosides are held 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 10.
Mention the similarities and dissimilarities of DNA and RNA.
Answer:
Similarities between DNA and RNA
The similarities between DNA and RNA are as follows-
- Both DNA and RNA are nucleic acids.
- Both are made up of pentose sugar, nitrogenous base and phosphate.
- Both are treated as bio-macromolecules.
- DNA and RNA carry same types of purines, i.e. adenine and guanine.
- Cytosine is present in both these molecules.
Dissimilarities between DNA and RNA
Features | DNA | RNA |
1. Occurrence | Nucleus, mitochondria and plastids | Cytopasm and ribosomes |
2. Physical structure | Double stranded helical molecule | Single stranded molecules with some loops |
3. Type of sugar | Deoxyribose sugar | Ribose sugar |
4. Nitrogenous base | Adenine, guanine, thymine and cytosine | Adenine, guanine, uracil and cytosine |
5. Genetic activity | Acts as the genetic material in all living cells | Acts as the genetic material in some viruses |
6. Function | Give all genetic commands to control every reaction and activity in a living cell or a living body | Helps in synthesis of polypeptide chains according to the command of DNA |
Question 11.
What is atherosclerosis? Mention the effects of fluorine overdose in human body.
Answer:
Atherosclerosis
When cholesterol percentage becomes excessive in blood, cholesterol is deposited and forms plaque on the inner wall of arteries. Thus, the arterial wall becomes thick. This condition is called as atherosclerosis. Atherosclerosis enhances the chances of heart failure.
Effects of fluorine overdose in human body
Presence of excess fluorine in drinking water has harmful effects on the teeth. The enamel of the teeth becomes weak and turns brownish in colour. It also results in the formation of cavity leading to a condition called dental fluorosis.
Apart from this, fluorine forms a cementing layer on spine and bones of legs, resulting in the loss of their natural flexibility. In addition to this, high fluoride ingestion can also cause a range of gastro-intestinal symptoms like nausea, pain and vomiting. Moreover, excess fluoride level in body results in polyuria (frequent urination), polydipsia (excessive thirst) and constipation followed by diarrhoea.
Question 12
Mention the role of different types of vitamin B in human body.
Answer:
Role of vitamin B in human body
Role of different types of vitamin B in human body are as follows-
1. Vitamin B1 (Thiamin):
- It helps in the oxidation of sugars in brain and muscular tissues.
- It catalyses the synthesis of proteins, fats and carbohydrates.
- It helps in general growth of the body.
2. Vitamin B2 (Riboflavin):
- It helps in cellular respiration.
- It helps in maintaining healthy skin.
- It catalyses the transformation of carbohydrates into fat.
3. Vitamin B3 (Nicotinic acid or Niacin):
- It catalyses the transformation of carbohydrates into lipids.
- It helps to stimulate the central nervous system.
- It helps in cellular respiration and metabolism.
4. Vitamin B5 (Pantothenic acid):
- It helps in the production of neurotransmitters in the body.
- It helps to relieve the human body from a number of detrimental problems, like asthma.
- It helps to prevent several neural problems like insomnia, depression etc.
5. Vitamin B6 (Pyridoxine):
- It catalyses the transformation of starch and proteins into fat.
- It helps in the synthesis of haemoglobin.
- It helps in protein metabolism.
6 Vitamin B9/M (Folic acid):
- It helps to produce healthy RBCs.
- It helps in DNA formation.
- It helps to maintain pregnancy and reduces the chance of premature delivery.
7. Vitamin B12 (Cyanocobalamine):
- It helps in hemopoiesis or formation of RBC.
- It catalyses the synthesis of nucleic acid.
- It helps to maintain normal growth and activity of nervous system.
Question 13.
Differentiate between water-soluble vitamins and fat-soluble vitamins.
Answer:
Differences between water-soluble vitamins and fat-soluble vitamins
Features | Water-soluble vitamins | Fat-soluble vitamins |
1. Absorption medium | Vitamins get dissolved in water and are absorbed through blood | Vitamins get dissolved in fat and are absorbed through blood |
2. Storage | These vitamins get stored according to the need of the body | These vitamins get stored in the body in excess quantity and cause hypervitaminosis |
3. Necessity | These vitamins should be taken regularly with food | These vitamins remain stored in the body and utilised whenever need arises |
4. Wastage | During cooking, heat results in partial destruction, or, wastage of these vitamins | During cooking, wastage or destruction of these vitamins is much less than that of water-soluble vitamins |
5. Example | Vitamin B-complex, vitamin C, vitamin P | Vitamin A, vitamin D, vitamin E, vitamin K |
Question 14.
Mention the various functions of amino acids. What is biological value of protein?
Answer:
Various functions of amino acids
The various functions of amino acids are as follows-
- Formation of protoplasm: Amino acids help in the formation of protoplasm in living cells. They also help in the production of proteins like elastin, keratin etc.
- Regulation of chemical reactions: Amino acids help in the synthesis of enzymes and also regulate different essential chemical reactions in the body.
- Formation of haemoglobin: They also help in the proper formation of haemoglobin.
- Antibody production: Amino acids help to produce antibodies in the body, which fight against many disease causing germs.
- Glucose formation: They heip in the formation of glucose by the process of gluconeogenesis.
Biological value of protein
Biological value of protein is a measure of the proportion of absorbed protein from a food, which becomes incorporated into the proteins of the organism. In adults, total protein consumed is not utilised in body building, instead, it is used in healing and rest is removed through excretion. The part of protein which is assimilated after absorption in the body, is the biological value of protein.
It is measured with the following formula-
\(\text { Biological value of protein }=\frac{\text { Nitrogen incorporated into the body on the test day }}{\text { Nitrogen absorbed in proteins on the test day }} \times 100\)
Question 15.
What do you understand by the terms macroelements and microelements? Mention general role of different minerais on physiological process of human body.
Answer:
Macroelements
The elements, which are required in large quantities for proper growth and development of human body, are known as macroelements. Example-Sodium (Na), potassium (K), chlorine (Cl), calcium (Ca), phosphorus (P) etc.
Microelements
The elements, which are required in minute quantities for proper growth and development of human body, are known as microelements. Example-Iron (Fe), boron (B), iodine (I), molybdenum (Mo), zinc (Zn), manganese (Mn), copper (Cu) etc.
General role of different minerals in human body
Different minerals play different roles on physiological processes, which are as follows-
- As cofactors of enzymes: Different minerals like iron, copper, manganese, zinc etc. act as cofactors of the enzymes.
- Maintenance of acid-base balance: Certain elements like sodium, potassium, chlorine etc. maintain acid-base balance within the body.
- Maintenance of water balance: Sodium helps in maintaining water balance within the body.
- Conduction of nerve impulse: Sodium and potassium play very important role in the conduction of nerve impulse.
- Control membrane permeability: Elements like calcium and potassium control membrane permeability of our body.
- Role in blood coagulation: Calcium acts as an essential blood-coagulating factor.
- Formation of skeletal structure: Calcium and phosphorus are the main building components of bones and teeth.