1. Which of the following organelles is least involved in protein synthesis?
a) Ribosome
b) Endoplasmic Reticulum
c) Golgi Apparatus
d) Lysosome
Answer: Lysosome
Explanation: Ribosomes, ER, and Golgi are all directly involved in protein synthesis and processing. Lysosomes are for digestion, not synthesis.
2. In human genetics, a heterozygous individual for a trait is best described as:
a) Homozygous dominant
b) Homozygous recessive
c) Having two different alleles
d) Expressing incomplete dominance
Answer: Having two different alleles
Explanation: Heterozygous = two different alleles (Aa). Homozygous = same alleles (AA or aa).
3. Which process contributes the most to genetic variation in sexually reproducing organisms?
a) Binary fission
b) Independent assortment of chromosomes
c) Mitosis
d) DNA replication
Answer: Independent assortment of chromosomes
Explanation: Independent assortment and crossing-over increase genetic variation; mitosis and DNA replication do not.
4. The functional unit of kidney is
a) Bowman’s capsule
b) Nephron
c) Loop of Henle
d) Glomerulus
Answer: Nephron
Explanation: Nephron filters blood and forms urine; other options are parts of nephron or structures but not the complete functional unit.
5. Which hormone directly increases blood calcium levels?
a) Calcitonin
b) Parathyroid hormone
c) Insulin
d) Aldosterone
Answer: Parathyroid hormone
Explanation: PTH increases blood calcium; calcitonin lowers it.
6. During photosynthesis, the ATP and NADPH produced are utilized in:
a) Light-dependent reactions
b) Calvin cycle
c) Photolysis of water
d) Oxygen evolution
Answer: Calvin cycle
Explanation: ATP and NADPH from light-dependent reactions are used in the Calvin cycle for carbon fixation.
7. Which macromolecule is the main component of the cell membrane?
a) Protein
b) Nucleic acid
c) Lipid
d) Polysaccharide
Answer: Lipid
Explanation: Phospholipids form the bilayer; proteins are embedded, but lipid is the main structural component.
8. Which statement about enzymes is correct?
a) They increase activation energy
b) They are consumed in reactions
c) They provide alternative reaction pathways
d) They are permanently altered after reaction
Answer: They provide alternative reaction pathways
Explanation: Enzymes lower activation energy by providing a favorable pathway; they are not consumed or permanently altered.
9. Crossing-over occurs during:
a) Prophase I of meiosis
b) Anaphase II of meiosis
c) Prophase of mitosis
d) Telophase I of meiosis
Answer: Prophase I of meiosis
Explanation: Homologous chromosomes exchange segments during Prophase I, creating variation.
10. Which of the following is NOT a function of the liver?
a) Detoxification
b) Glycogen storage
c) Production of bile
d) Secretion of insulin
Answer: Secretion of insulin
Explanation: Insulin is secreted by the pancreas, not the liver.
11. In DNA replication, the enzyme responsible for unwinding the double helix is:
a) Ligase
b) Helicase
c) Polymerase
d) Primase
Answer: Helicase
Explanation: Helicase separates DNA strands; polymerase synthesizes new strands; ligase joins fragments.
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12. Which statement about arteries is FALSE?
a) They carry oxygenated blood away from the heart
b) They have thick muscular walls
c) They contain valves
d) Blood pressure is higher than in veins
Answer: They contain valves
Explanation: Arteries do not usually have valves; veins do.
13. Which phenomenon explains why males are more affected by X-linked recessive disorders?
a) Dosage compensation
b) Hemizygosity
c) Codominance
d) Polygenic inheritance
Answer: Hemizygosity
Explanation: Males have only one X chromosome, so any recessive allele on it is expressed.
14. Which type of immunity is acquired by injection of antibodies?
a) Active natural immunity
b) Active artificial immunity
c) Passive natural immunity
d) Passive artificial immunity
Answer: Passive artificial immunity
Explanation: Injection of antibodies = passive immunity; artificial because it’s introduced externally.
15. Which gas is mainly responsible for global warming?
a) Nitrogen B)
b) Carbon dioxide
c) Oxygen D)
d) Argon
Answer: Carbon dioxide
Explanation: CO₂ traps heat in the atmosphere; nitrogen and oxygen are abundant but not greenhouse gases.
16. Which blood component helps in clotting?
a) Red blood cells
b) Platelets
c) Plasma
d) White blood cells
Answer: Platelets
Explanation: Platelets initiate clotting; RBCs carry oxygen; WBCs fight infection.
17. Which of the following is a C4 plant?
a) Wheat
b) Maize
c) Rice
d) Barley
Answer: Maize
Explanation: Maize is C4; wheat, rice, and barley are C3 plants.
18. Which molecule stores genetic information in retroviruses?
a) DNA
b) RNA
c) Protein
d) Polysaccharide
Answer: RNA
Explanation: Retroviruses have RNA genomes; DNA is formed after reverse transcription.
19. Which type of transport requires both ATP and carrier proteins?
a) Simple diffusion
b) Facilitated diffusion
c) Active transport
d) Osmosis
Answer: Active transport
Explanation: Active transport moves substances against the concentration gradient using ATP.
20. Which of the following is NOT involved in the human immune response?
a) Lymphocytes
b) Macrophages
c) Neutrophils
d) Erythrocytes
Answer: Erythrocytes
Explanation: Red blood cells carry oxygen, not immune function. Lymphocytes, macrophages, and neutrophils are immune cells.
