Explore Class 10 Biology Chapter 13 – Biochemistry, covering the main biomolecules of life: carbohydrates, proteins, lipids, nucleic acids, and vitamins.
Carbohydrates provide energy and are found in fruits, vegetables, cereals, and milk. Proteins are made of amino acids and help build body tissues. Lipids like fats and oils store energy. Nucleic acids (DNA and RNA) carry genetic information and help make proteins. Vitamins support growth, development, and overall health.
These notes include MCQs, short questions, and long questions, making them perfect for quick revision and exam preparation.
Important MCQs – Chapter 13 Hydrocarbons
1. Which of the following is the main source of energy for humans?
(a) Proteins
(b) Lipids
(c) Vitamins
(d) Carbohydrates ✅
2. Lipids are composed of:
(a) Glucose
(b) Nucleotides
(c) Fatty acids ✅
(d) Amino acids
3. What is the role of RNA in cells?
(a) Energy storage
(b) Protein formation ✅
(c) Genetic storage
(d) Vitamin absorption
4. What is the general formula of carbohydrates?
(a) CH₄
(b) C₆H₁₂O₆
(c) CO₂ + H₂O
(d) C(H₂O) ✅
5. How many amino acids are present in proteins?
(a) Less than 100
(b) More than 10,000 ✅
(c) Only 20
(d) About 1000
Short Questions – Chapter 13 Hydrocarbons
1. How do plants synthesize carbohydrates?
Answer:
Plants synthesize carbohydrates through photosynthesis. In this process, plants use carbon dioxide (CO2) from the air and water (H2O) from the soil, in the presence of sunlight and chlorophyll, to produce glucose (C6H12O6) and release oxygen (O2).
Equation:
6 CO2 + 6 H2O → C6H12O6 + 6 O2 (in presence of sunlight and chlorophyll)
Explanation:
-
CO2 provides carbon, H2O provides hydrogen and oxygen, and sunlight provides energy.
-
Glucose is used as an energy source by plants and animals.
-
Oxygen released is essential for respiration in living organisms.
2. What is the difference between glucose and fructose?
Answer:
-
Glucose is an aldose sugar, which means it contains an aldehyde group.
-
Fructose is a ketose sugar, which means it contains a ketone group.
-
Both have the same chemical formula: C6H12O6.
-
Glucose is found in fruits, vegetables, and blood.
-
Fructose is mainly found in fruits and honey.
-
Fructose is sweeter in taste than glucose.
-
Their structures are different, even though both are monosaccharides.
Key Points:
-
Glucose → Aldose → Found in fruits, vegetables, blood
-
Fructose → Ketose → Found in fruits, honey → Sweeter than glucose
3. Where are the proteins found?
Answer:
Proteins are found in the following food sources:
-
Meat
-
Butter
-
Chicken
-
Fish
-
Eggs
Explanation:
Proteins are essential for growth, repair, and maintenance of body tissues. Animal-based foods like meat, eggs, fish, and dairy are rich sources of high-quality proteins containing all essential amino acids.
4. Describe the sources and uses of Vitamin A.
Answer:
Sources of Vitamin A:
-
Carrots
-
Milk
-
Butter
-
Egg yolk
-
Green vegetables
Uses of Vitamin A:
-
Maintains healthy vision
-
Promotes growth of skin and tissues
-
Strengthens the immune system
5. What is the function of DNA?
Answer:
-
Stores genetic information in all living organisms.
-
Transfers genetic information from one generation to the next.
-
Controls the synthesis of RNA and proteins, regulating cellular activities.
-
Maintains the identity and proper functioning of each cell.
Explanation:
DNA (Deoxyribonucleic Acid) is a double-stranded nucleic acid that carries hereditary information. It ensures that offspring inherit traits from their parents and directs protein synthesis, which is essential for growth, repair, and normal functioning of cells.
Long Questions – Chapter 13 Hydrocarbons
Q1: Give the importance of vitamins.
Introduction:
Vitamins are organic compounds required in very small amounts for the proper growth, development, and normal functioning of the human body. Unlike carbohydrates, proteins, and fats, vitamins do not provide energy, but they are essential for life because they regulate many metabolic and physiological processes.
Importance of Vitamins:
1. Regulation of Body Functions
Vitamins help regulate metabolism, digestion, nerve functions, and other vital processes. For example, B-complex vitamins act as coenzymes in many metabolic reactions, ensuring that the body efficiently converts food into energy.
2. Strengthening the Immune System
Vitamins like Vitamin C and E enhance the body’s defense mechanisms against infections. They help white blood cells function properly, improving immunity and reducing the risk of diseases.
3. Healthy Skin, Eyes, and Hair
-
-
Vitamin A is essential for maintaining good vision, particularly night vision.
-
It also supports the growth and repair of skin and body tissues, keeping the skin, hair, and mucous membranes healthy.
-
4. Bone Health
-
Vitamin D helps the body absorb calcium and phosphorus, which are necessary for strong bones and teeth.
-
A deficiency of Vitamin D can lead to rickets in children and osteomalacia in adults.
-
Wound Healing and Blood Clotting
-
Vitamin K is essential for blood clotting, preventing excessive bleeding.
-
Vitamin C helps in collagen formation, repairing tissues, and healing wounds effectively.
-
-
Energy Production
-
B-complex vitamins, including B1, B2, B3, B6, B12, act as coenzymes in energy metabolism. They help convert carbohydrates, fats, and proteins from food into usable energy (ATP) for the body.
-
-
Prevention of Deficiency Diseases
Vitamins prevent several deficiency disorders:-
Rickets → Lack of Vitamin D
-
Scurvy → Lack of Vitamin C
-
Night Blindness → Lack of Vitamin A
-
Summary:
Even though vitamins are needed in tiny amounts, they are crucial for health and survival. They support metabolism, immunity, vision, bone health, tissue repair, and energy production. A balanced diet including fruits, vegetables, dairy products, and grains ensures the body receives all essential vitamins.
Download PDF
Get the complete chapter notes in PDF for thorough study and easy revision.
English Medium
👉 View English Medium
Urdu Medium
👉 View Urdu Medium PDF