Matric Notes Chemistry 10th Chapter 13 Biochemistry Exercise Short Questions

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1. How plants synthesize carbohydrates?

Ans. Carbohydrates are synthesized by plants through photosynthesis process from CO2 and H2O in the presence of sunlight and green pigment chlorophyll. 

6CO₂ + 6H₂O -----> C₆H₁₂O₆ + 6O₂

                    Glucose

The glucose is further polymerized to form starch and cellulose.

2. Give the characteristics of monosaccharides.

Ans. Characteristics of monosaccharides are:

1. Monosaccharides are white crystalline solids.
2. They are soluble in water.
3. They have sweet taste.
4. They cannot be hydrolyzed.
5. They are reducing in nature therefore they are called reducing sugars.

3. What is the difference between glucose and fructose?

Ans. Glucose is a pentahydroxy aldehyde while fructose is pentahydroxy ketone having an open chain structure.

Structure of Glucoce:

Structure of Fructose:

4. Give an example of disaccharides. How is it hydrolyzed into monosaccharides?

Ans. Sucrose is an example of a diasaccharide which on hydrolysis produces one molecule of glucose and one molecule of fructose.

C₁₂H₂₂O₁₁ + H₂O ---->  C₆H₁₂O₆ + C₆H₁₂O₆

5. Give the characteristics of polysaccharides.

Ans. Characteristics of polysaccharides:

1. Polysaccharides are amorphous solids.
2. They are insoluble in water.
3. They are tasteless.
4. They are non-reducing compounds.

6. Where are the proteins formed?

Ans. Sources of Protein:

Proteins make up more than 50% of the dry weight of animals.

1. Animal’s proteins are meat, mutton, chicken, fish, eggs.
2. Enzymes are proteins that are produced by the living cells.
3. Hides are proteins.
4. Proteins are found in bones.
5. Plants also synthesize proteins such as pulses, beans, etc.

7. Describe the uses of carbohydrates.

Ans. Uses of carbohydrates:

Carbohydrates are energy providing materials. They also provide the following usage to our body.

1. They regulate the amount of sugar level in our body. Low sugar level in body results in hypoglycemia.
2. They provide essential nutrients for bacteria in intestinal tract that helps indigestion.
3. Dietary fibre helps to keep the bowel functioning properly.
4. Fibre helps in lowering of cholesterol level and regulates blood pressure.
5. They protect our muscles from cramping.

8. Lactose is diasaccharide, which monosaccharides are present in it.?

Ans. In lactose, the monosaccharides, glucose and galactose are present.

9. Why are ten amino acids essential for us?

Ans. Amino acids are the building blocks of protein. Human body cannot synthesize ten amino acids called essential amino acids, therefore, they must be supplied through diet.

10. How are proteins formed?

Ans. Formation of Proteins:

Two amino acids link through peptide linkage. Peptide linkage is formed by the elimination of water molecule between the amino group of one amino acid and carboxyl group of another amino acid.

When thousands of amino acids polymerize they form proteins.

For Example:

11. How is gelatin obtained?

Ans. Gelatin is a protein which is obtained on heating bones. It is used to make bakery items.

12. Give the general formula of the lipids.

Ans. General formula of lipids. (Triglyceride) is:

The three R groups can be the  same or different groups within the same far or oil and they can be saturated or unsaturated.

13. Name two fatty acids with their formulae.

Ans. Fatty Acids:

Palmitic acid C₁₅H₃₁COOH

Stearic Acid C₁₇H₃₅COOH

14. Give the types of vitamins.

Ans. Vitamins are divided into two types:

1. Fat soluble vitamins
2. Water Soluble vitamins

Fat soluble vitamins:

The vitamins which dissolve in fats are called fat soluble vitamins. These are vitamin A, D, E and K.

Water soluble vitamins:

The vitamins that dissolve in water are called water soluble vitamins. Examples of these vitamins are B-complex (this include 10 vitamins) and vitamin C (ascorbic acid).

15. What is the significance of vitamins?

Ans. Significance of vitamins:

1. Each vitamin plays an important role in healthy development of our body.
2. Natural vitamins are organic food substances found only in plants and animals. Our body is unable to synthesize vitamins. Because of this, they must be supplied either directly in the diet or by way of dietary supplements. They are absolutely necessary for our normal growth.
3. Vitamins cannot be assimilated without ingesting food. This is why, it is suggested that vitamins must be taken with meal. They help to regulate our body’s metabolism.

16. Describe the sources and use of vitamin A.

Ans. Sources: Dairy products, eggs, oils and fats, fish. It can also be obtained from the beta-carotene found in green vegetables, carrots and lives.

Uses: It is used to maintain the health of the epithelium and acts on the retina’s dark adaptation mechanism.

17. Justify water soluble vitamins are not injurious to health.

Ans. Water soluble vitamins are rapidly excreted from the body. Hence these vitamins are not toxic even if taken in large quantity. However, their deficiency causes disease.

18. What do you mean by genetic code of life?

Ans. DNA carries and stores all genetic information of the cell, which are called ‘genetic code of life’. These instructions determine whether an organism is a man or a tree or a donkey and whether a cell is a nerve cell or a muscle cell.

19. What is the function of DNA?

Ans. DNA is the permanent storage place for genetic information in the nucleus of a cell. It carries and stores all genetic information of the cell. It passes these information as instructions from generation to generation how to synthesize particular proteins from amino acids. It carries genes that control the synthesis of RNA.

20. How do you justify RNA works like a messenger?

Ans. RNA is synthesized by DNA to transmit the genetic information. RNA receives, reads, decodes and uses the given information to synthesize new proteins. Its role is like a messenger.