✅ DAT Biology Practice Exam – Answer Key & Explanations
1. B — Ribosome
Ribosomes are the site of protein synthesis, translating mRNA into amino acid chains.
2. A — Prophase → Metaphase → Anaphase → Telophase
This is the correct chronological order of mitotic stages (PMAT).
3. C — Oxygen
Oxygen acts as the final electron acceptor during aerobic respiration, forming water.
4. D — G–C
In DNA, guanine pairs with cytosine via three hydrogen bonds.
5. B — 0.7
If 9% are homozygous recessive (q² = 0.09), then q = 0.3 and p = 1 - 0.3 = 0.7.
6. C — Cerebellum
The cerebellum is responsible for fine motor coordination and balance.
7. B — Water absorption
The large intestine absorbs water and electrolytes, forming solid waste.
8. B — LH
Luteinizing hormone (LH) spikes mid-cycle and causes ovulation.
9. C — Circular DNA
Prokaryotes lack nuclei and membrane-bound organelles but have circular DNA in the nucleoid.
10. B — Both organisms benefit
Mutualism is a symbiotic relationship where both organisms gain a benefit.
11. B — To carry amino acids to the ribosome
tRNA reads mRNA codons and brings the corresponding amino acid for protein assembly.
12. B — Urea production
The liver converts ammonia (toxic) into urea, which is excreted by the kidneys.
13. D — Tundra
Tundras have permanently frozen soil (permafrost), cold temperatures, and short growing seasons.
14. B — Small intestine
Most nutrient absorption, including carbohydrates, proteins, and fats, occurs in the small intestine.
15. C — Photosynthesis
Photosynthesis occurs in chloroplasts using sunlight to convert CO₂ and H₂O into glucose and oxygen.
16. C — Xylem
Xylem conducts water and minerals upward from the roots to the rest of the plant.
17. C — Antibodies
Antibodies are part of the adaptive immune response, not the innate system.
18. C — Meiosis
Meiosis results in four genetically unique haploid gametes.
19. B — Human appendix
The appendix is a vestigial structure—once useful in herbivorous digestion, but now largely nonfunctional.
20. D — Muscle contraction
Sarcomeres are repeating units in muscle fibers responsible for contraction via actin and myosin interaction.
