General Biology MCQs

Here are some biology MCQs.

1. Which organelle is responsible for photosynthesis in plant cells?

a) Mitochondria

b) Nucleus

c) Chloroplasts

d) Endoplasmic reticulum

Answer: c) Chloroplasts

Explanation:

Chloroplasts are the organelles responsible for photosynthesis, where plants convert sunlight into chemical energy in the form of glucose.

2. Which of the following is NOT a function of the liver?

a) Protein synthesis

b) Detoxification

c) Digestion of food

d) Storage of glycogen

Answer: c) Digestion of food

Explanation:

The liver is involved in many important functions, including protein synthesis, detoxification, and storage of glycogen. However, digestion of food primarily occurs in the stomach and small intestine.

3. Which process is responsible for the movement of water through a plant from the roots to the leaves?

a) Osmosis

b) Transpiration

c) Photosynthesis

d) Respiration

Answer: b) Transpiration

Explanation:

Transpiration is the process by which water is pulled up from the roots to the leaves of a plant due to the loss of water vapor through tiny openings called stomata in the leaves.

4. In which stage of the cell cycle does DNA replication occur?

a) G1 phase

b) S phase

c) G2 phase

d) M phase

Answer: b) S phase

Explanation:

DNA replication occurs during the S phase (Synthesis phase) of the cell cycle, where the DNA is copied before cell division.

5. Which of the following blood vessels carries oxygenated blood away from the heart to the body’s tissues?

a) Veins

b) Arteries

c) Capillaries

d) Aorta

Answer: b) Arteries

Explanation:

Arteries carry oxygenated blood away from the heart to supply oxygen and nutrients to the body’s tissues.

6. What is the primary function of white blood cells (leukocytes) in the immune system?

a) Carrying oxygen

b) Clotting blood

c) Fighting infections

d) Transporting nutrients

Answer: c) Fighting infections

Explanation:

White blood cells are a vital part of the immune system and their primary function is to defend the body against infections and foreign invaders.

7. Which gas is exchanged in the alveoli of the lungs during respiration?

a) Carbon dioxide (CO2)

b) Oxygen (O2)

c) Nitrogen (N2)

d) Hydrogen (H2)

Answer: b) Oxygen (O2)

Explanation:

In the alveoli of the lungs, oxygen is taken in from the air and carbon dioxide is released as waste during the process of respiration.

8. Which of the following is a product of cellular respiration?

a) Glucose

b) Oxygen

c) Carbon dioxide

d) Water

Answer: c) Carbon dioxide

Explanation:

Cellular respiration is the process by which cells produce energy (ATP) by breaking down glucose and oxygen, producing carbon dioxide as a waste product.

9. Which of the following is a nitrogenous waste product excreted by humans?

a) Urea

b) Glucose

c) Amino acids

d) Fatty acids

Answer: a) Urea

Explanation:

Urea is the primary nitrogenous waste product excreted by humans. It is formed in the liver as a result of protein metabolism and is eliminated by the kidneys.

10. What is the function of the ribosomes in a cell?

a) Synthesizing lipids

b) Producing energy

c) Protein synthesis

d) Storing genetic information

Answer: c) Protein synthesis

Explanation:

Ribosomes are cellular structures responsible for protein synthesis, where amino acids are assembled into polypeptide chains.

11. Which of the following is a greenhouse gas that contributes to climate change?

a) Oxygen (O2)

b) Nitrogen (N2)

c) Carbon dioxide (CO2)

d) Hydrogen (H2)

Answer: c) Carbon dioxide (CO2)

Explanation:

Carbon dioxide is a greenhouse gas that traps heat in the Earth’s atmosphere, leading to global warming and climate change.

12. What is the function of the enzyme amylase in the digestive system?

a) Breaking down fats

b) Breaking down proteins

c) Breaking down starches into sugars

d) Absorbing water

Answer: c) Breaking down starches into sugars

Explanation:

Amylase is an enzyme that breaks down complex carbohydrates (starches) into simpler sugars, such as glucose, in the digestive system.

13. Which of the following blood types is known as the “universal donor”?

a) A+

b) B-

c) AB+

d) O-

Answer: d) O-

Explanation:

O-negative (O-) blood type is considered the “universal donor” because it lacks A, B, and Rh antigens, making it compatible with all other blood types.

14. What is the function of the hormone insulin in the human body?

a) Regulating blood sugar levels

b) Stimulating growth hormone production

c) Controlling blood pressure

d) Enhancing muscle strength

Answer: a) Regulating blood sugar levels

Explanation:

Insulin is a hormone produced by the pancreas, and its primary function is to regulate blood sugar (glucose) levels by facilitating the uptake of glucose into cells.

15. Which process is responsible for the formation of gametes (sperm and egg cells) in humans?

a) Meiosis

b) Mitosis

c) Fertilization

d) Budding

Answer: a) Meiosis

Explanation: 

Meiosis is the specialized cell division process that produces haploid gametes with half the chromosome number of somatic cells.