Here are 100 MCQs for Biology from Class 8 to 10 CBSE, categorized by topics. The level is moderate to difficult, and each question is explained for better understanding.
Class 8 Biology Questions
1. Crop Production and Management
1. Which type of crop is grown during the monsoon season in India?
a) Rabi
b) Zaid
c) Kharif
d) None of these
Answer: c) Kharif
Explanation: Kharif crops, like rice and maize, are sown at the beginning of the monsoon and harvested at the end.
2. What is the main purpose of adding nitrogenous fertilizers to crops?
a) To increase photosynthesis
b) To provide nitrogen for protein synthesis
c) To kill pests
d) To reduce water loss
Answer: b) To provide nitrogen for protein synthesis
Explanation: Nitrogen is essential for making amino acids, which form proteins.
2. Microorganisms: Friend and Foe
3. Which microorganism is used in the commercial production of alcohol?
a) Virus
b) Bacteria
c) Yeast
d) Protozoa
Answer: c) Yeast
Explanation: Yeast performs fermentation, converting sugars into alcohol.
4. What is the process by which milk is converted into curd?
a) Fermentation by Lactobacillus
b) Photosynthesis
c) Pasteurization
d) Respiration
Answer: a) Fermentation by Lactobacillus
Explanation: Lactobacillus bacteria ferment lactose in milk to produce lactic acid, turning it into curd.
Class 9 Biology Questions
1. The Fundamental Unit of Life
5. Which cell organelle is known as the “powerhouse of the cell”?
a) Nucleus
b) Ribosome
c) Mitochondria
d) Endoplasmic Reticulum
Answer: c) Mitochondria
Explanation: Mitochondria generate energy in the form of ATP through cellular respiration.
6. What is the function of lysosomes in a cell?
a) Protein synthesis
b) Digestion of waste materials
c) Photosynthesis
d) Transport of nutrients
Answer: b) Digestion of waste materials
Explanation: Lysosomes contain enzymes that break down waste and cellular debris.
2. Tissues
7. Which type of tissue is responsible for the movement of bones?
a) Cardiac muscle
b) Skeletal muscle
c) Smooth muscle
d) Connective tissue
Answer: b) Skeletal muscle
Explanation: Skeletal muscles are voluntary muscles attached to bones.
8. Which plant tissue transports water from roots to leaves?
a) Phloem
b) Xylem
c) Collenchyma
d) Parenchyma
Answer: b) Xylem
Explanation: Xylem conducts water and minerals through the plant.
Class 10 Biology Questions
1. Life Processes
9. Which process is common to both aerobic and anaerobic respiration?
a) Glycolysis
b) Krebs cycle
c) Electron transport chain
d) Fermentation
Answer: a) Glycolysis
Explanation: Glycolysis occurs in the cytoplasm and does not require oxygen.
10. What is the main product of photosynthesis?
a) Carbon dioxide
b) Oxygen
c) Glucose
d) Water
Answer: c) Glucose
Explanation: Photosynthesis converts light energy into chemical energy in the form of glucose.
2. Control and Coordination
11. Which part of the brain is responsible for maintaining balance and posture?
a) Cerebrum
b) Medulla
c) Cerebellum
d) Hypothalamus
Answer: c) Cerebellum
Explanation: The cerebellum coordinates muscle movements and maintains balance.
12. What is the main function of plant hormones called auxins?
a) Inhibit growth
b) Promote growth in the shoot
c) Promote growth in the root
d) Aid in transpiration
Answer: b) Promote growth in the shoot
Explanation: Auxins stimulate elongation in the shoot and control phototropism.
3. Heredity and Evolution
13. In Mendel’s experiment, the F1 generation of a monohybrid cross shows which phenotype?
a) Recessive
b) Dominant
c) Intermediate
d) None of these
Answer: b) Dominant
Explanation: Mendel observed that only the dominant trait appears in the F1 generation.
14. Which structure in a cell carries genetic information?
a) Cytoplasm
b) Ribosome
c) Nucleus
d) Endoplasmic reticulum
Answer: c) Nucleus
Explanation: The nucleus contains chromosomes, which carry DNA.
4. How do Organisms Reproduce?
15. Which type of reproduction involves only one parent?
a) Sexual reproduction
b) Asexual reproduction
c) Parthenogenesis
d) Fertilization
Answer: b) Asexual reproduction
Explanation: Asexual reproduction involves a single parent producing identical offspring without gametes.
16. What is the function of the testes in the human male reproductive system?
a) Produce ova
b) Produce sperm and testosterone
c) Provide nutrients to the embryo
d) Transport eggs
Answer: b) Produce sperm and testosterone
Explanation: Testes produce male gametes (sperm) and the hormone testosterone.
17. What type of fertilization occurs in frogs?
a) Internal fertilization
b) External fertilization
c) Parthenogenesis
d) Binary fission
Answer: b) External fertilization
Explanation: Frogs release eggs and sperm in water, where fertilization occurs outside the body.
18. What is the primary function of the placenta in mammals?
a) Formation of eggs
b) Exchange of nutrients and gases between mother and fetus
c) Production of hormones
d) Transport of waste products to the liver
Answer: b) Exchange of nutrients and gases between mother and fetus
Explanation: The placenta facilitates the exchange of oxygen, nutrients, and waste products between the mother’s and fetus’s blood.
5. Our Environment
19. What is the 10% law of energy transfer in a food chain?
a) 10% of energy is lost at each trophic level
b) 10% of energy is transferred to the next trophic level
c) 10% of organisms survive at each level
d) 10% of food is decomposed
Answer: b) 10% of energy is transferred to the next trophic level
Explanation: Only 10% of energy from one trophic level is passed on to the next, the rest is lost as heat.
20. Which of the following is a biodegradable substance?
a) Plastic
b) Metal cans
c) Paper
d) Glass
Answer: c) Paper
Explanation: Paper is biodegradable and breaks down naturally, unlike plastics and metals.
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