Questions and Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. Which organelle is responsible for producing ATP during aerobic cellular
respiration?
A. Golgi apparatus
B. Ribosome
C. Mitochondrion
D. Lysosome
Answer: C. Mitochondrion
Rationale: The mitochondrion is the primary site of aerobic cellular respiration,
where glucose is converted into ATP through the Krebs cycle and electron
transport chain.
2. DNA replication occurs during which phase of the cell cycle?
A. G1 phase
B. S phase
C. G2 phase
D. M phase
Answer: B. S phase
Rationale: During the S (synthesis) phase, each chromosome is duplicated so that
two identical sister chromatids are available for cell division.
,3. Which molecule carries genetic information in most living organisms?
A. ATP
B. RNA
C. Protein
D. DNA
Answer: D. DNA
Rationale: DNA stores hereditary information and provides the instructions for
protein synthesis in nearly all organisms.
4. Which process produces genetically identical daughter cells?
A. Meiosis
B. Fertilization
C. Mitosis
D. Crossing over
Answer: C. Mitosis
Rationale: Mitosis results in two genetically identical daughter cells used for
growth, repair, and asexual reproduction.
5. Which nitrogenous base pairs with adenine in DNA?
A. Cytosine
B. Guanine
C. Uracil
D. Thymine
Answer: D. Thymine
,Rationale: According to complementary base-pairing rules, adenine pairs with
thymine in DNA.
6. Which macromolecule functions primarily as an enzyme?
A. Lipid
B. Carbohydrate
C. Protein
D. Nucleic acid
Answer: C. Protein
Rationale: Most enzymes are proteins that speed up biochemical reactions by
lowering activation energy.
7. What is the basic unit of biological classification?
A. Genus
B. Family
C. Species
D. Kingdom
Answer: C. Species
Rationale: A species consists of organisms capable of interbreeding and producing
fertile offspring.
8. Photosynthesis occurs mainly in which organelle?
A. Ribosome
B. Vacuole
C. Chloroplast
, D. Nucleus
Answer: C. Chloroplast
Rationale: Chloroplasts contain chlorophyll and carry out photosynthesis in plants
and algae.
9. Which gas is released during photosynthesis?
A. Carbon dioxide
B. Nitrogen
C. Hydrogen
D. Oxygen
Answer: D. Oxygen
Rationale: Oxygen is released when water molecules are split during the light-
dependent reactions.
10. Which molecule is the primary energy source for cells?
A. DNA
B. Protein
C. ATP
D. Glycogen
Answer: C. ATP
Rationale: ATP stores and transfers energy for nearly all cellular activities.
11. Which kingdom contains multicellular organisms that absorb nutrients from
their environment?
A. Plantae