Chapter – 4 : Biomolecules and their Functions | Chapter Solution Class 9

(a) Carbohydrates

Explanation:

Carbohydrates are the primary source of energy in the body. They break down into glucose, which is used for energy production through cellular respiration.

(d) Vitamin

Explanation:

Vitamins are essential organic compounds required for body functions, but they do not provide energy. Unlike carbohydrates, proteins, and fats, vitamins serve as coenzymes in metabolic processes.

(c) Protein

Explanation:

Proteins are made up of amino acids that contain nitrogen. This nitrogen is essential for the synthesis of new proteins, enzymes, and nucleic acids in the body.

(c) Fat

Explanation:

Fats (lipids) are composed of glycerol and fatty acids. When fats are broken down, glycerol is released and can be used in energy metabolism.

(a) Regulation of body temperature

Explanation:

Proteins are involved in growth, tissue repair, enzyme production, and other biological functions, but they do not regulate body temperature. Temperature regulation is primarily controlled by metabolic activities and the hypothalamus.

(b) Vitamin C

Explanation:

Water-soluble vitamins include Vitamin C and B-complex vitamins. These vitamins dissolve in water and are not stored in the body, requiring regular intake.

(a) Vitamin A

Explanation:

Vitamin A is essential for vision, particularly in low-light conditions. Its deficiency leads to night blindness, a condition where the eyes have difficulty adjusting to darkness.

(c) Vitamin D

Explanation:

Vitamin D is crucial for calcium absorption, which is necessary for strong bones. A deficiency in children leads to rickets, a disease characterized by weak and deformed bones.

(d) Iron in food

Explanation:

Iron is essential for the production of hemoglobin, the oxygen-carrying component of red blood cells. A deficiency in iron leads to anemia, causing fatigue and weakness due to insufficient oxygen supply to tissues.

Nitrogen

Explanation:

Proteins are composed of amino acids, which contain nitrogen as a key element. Unlike carbohydrates and fats, proteins have nitrogen, which is essential for growth and tissue repair.

Vitamin B₁ (Thiamine)

Explanation:

Beriberi is caused by a deficiency of vitamin B₁ (Thiamine). This vitamin plays a crucial role in nerve function and energy metabolism. Its deficiency leads to weakness, nerve damage, and cardiovascular issues.

Vitamin C

Explanation:

Scurvy is a disease caused by a deficiency of vitamin C, which is essential for collagen synthesis and immune function. Symptoms include bleeding gums, weakness, and delayed wound healing.

Protein.

Night-blindness (Nyctalopia).

Vitamin A, D, E, or K.

Vitamin C or B-complex vitamins.

Vitamin K

Vitamin D

Vitamin D

Vitamin C (Ascorbic Acid)

Plants synthesize their own vitamins through biochemical processes using sunlight, water, and soil nutrients.

A nucleotide is the basic structural unit of nucleic acids (DNA & RNA), composed of a nitrogenous base, a sugar molecule, and a phosphate group.

Nitrogen base (Adenine, Thymine, Cytosine, Guanine in DNA; Uracil instead of Thymine in RNA)

Pentose sugar (Deoxyribose in DNA, Ribose in RNA)

Phosphate group

A nucleoside is a structural component of nucleotides that consists of a nitrogenous base and a pentose sugar, but without the phosphate group.

Deoxyribonucleic Acid.

Ribonucleic Acid.

James Watson and Francis Crick (1953), with contributions from Rosalind Franklin and Maurice Wilkins.

Protein: Egg

Carbohydrate: Rice

Polysaccharides are complex carbohydrates made up of many monosaccharide units.

Example: Starch, Glycogen, Cellulose

Animal Sources: Butter, Fish oil

Plant Sources: Coconut oil, Olive oil

Carbohydrate:

• Plant Source: Wheat
• Animal Source: Milk

Protein:

• Plant Source: Soybean
• Animal Source: Chicken

Fat:

• Plant Source: Sunflower oil
• Animal Source: Butter

Fats (lipids) are organic compounds composed of glycerol and fatty acids.

Examples:

• Animal Source: Butter
• Plant Source: Coconut oil

Vitamins are organic compounds required in small amounts for normal growth and metabolism.

Example: Vitamin C

• Fat-Soluble Vitamins: A, D, E, K
• Water-Soluble Vitamins: B-complex, C

Vitamin K is known as an anti-hemorrhagic factor because it helps in blood clotting.

Carbon (C)

Hydrogen (H)

Oxygen (O)

Nitrogen (N)

Essential Elements: Required in large amounts (e.g., Carbon, Nitrogen, Calcium).

Trace/Microelements: Required in small amounts (e.g., Iron, Zinc, Copper).

An enzyme is a biological catalyst that speeds up chemical reactions in living organisms.

Example: Amylase

Highly specific for their substrate.

Function optimally at a particular pH and temperature.

Increase the rate of biochemical reactions.

Vitamin E Deficiency: Muscle weakness, vision issues.

Vitamin K Deficiency: Excessive bleeding, delayed clotting.

The functions of DNA are:

1. It stores genetic information.
2. It guides protein synthesis.
3. It transfers hereditary traits.

The functions of RNA are:

• Carries genetic instructions from DNA to ribosomes.
• Helps in protein synthesis.
• Plays a role in gene regulation.

The nutritional importance of carbohydrates are:

1. Carbohydrates provide instant energy through glucose metabolism.
2. Excess carbohydrates are stored as glycogen in animals and starch in plants.
3. Cellulose in plant-based foods aids digestion and prevents constipation.
4. Carbohydrates maintain glucose levels and prevent hypoglycemia.
5. The brain depends on glucose for proper functioning.

The nutritional importance of fat are:

1. Fats provide more energy per gram (9 kcal/g) compared to carbohydrates and proteins.
2. Fats insulate the body and protect organs from physical damage.
3. Vitamins A, D, E, and K require fat for absorption.
4. Fats help in the synthesis of essential hormones like estrogen and testosterone.
5. Lipids form the structural component of cell membranes (phospholipid bilayer).

(a) Definition:

Vitamins are organic compounds required in small amounts for normal physiological functions but do not provide energy.

(b) Classification Based on Solubility:

1. Fat-Soluble Vitamins: Stored in fat tissues and liver. Examples – Vitamin A, D, E, K.
2. Water-Soluble Vitamins: Not stored in the body, requiring daily intake. Examples – Vitamin B-complex, Vitamin C.

The importance/significance of vitamins are

1. Vitamins act as coenzymes in biochemical reactions.
2. Vitamins like C and E help strengthen the immune system.
3. Vitamins support cell growth and differentiation (e.g., Vitamin A for vision).
4. Vitamin K is essential for blood coagulation.
5. Lack of vitamins leads to disorders such as rickets (Vitamin D deficiency) and scurvy (Vitamin C deficiency).

Importance of water in nutrition are:

1. Dissolves nutrients for cellular functions.
2. Helps break down food and transport nutrients.
3. Controls heat through sweating and respiration.
4. Essential for excretion via urine and sweat.
5. Water is a raw material for photosynthesis, helping in glucose synthesis.