1. Which enzyme is responsible for synthesizing the leading strand continuously during DNA replication in prokaryotes?

  • A. DNA polymerase I
  • B. DNA polymerase II
  • C. DNA polymerase III
  • D. RNA polymerase

Answer: C. DNA polymerase III

Explanation: DNA polymerase III is the principal enzyme responsible for continuous synthesis of the leading strand and discontinuous synthesis of the lagging strand.

2. Which of the following blood vessels carries deoxygenated blood from the heart to the lungs?

  • A. Aorta
  • B. Pulmonary vein
  • C. Pulmonary artery
  • D. Coronary artery

Answer: C. Pulmonary artery

Explanation: The pulmonary artery is unique because it carries deoxygenated blood from the right ventricle to the lungs for oxygenation.

3. Which hormone lowers blood calcium concentration by promoting calcium deposition in bones?

  • A. Parathyroid hormone
  • B. Calcitonin
  • C. Aldosterone
  • D. Thyroxine

Answer: B. Calcitonin

Explanation: Calcitonin, secreted by the thyroid gland, decreases blood calcium levels by inhibiting osteoclast activity.

4. The anticodon UAC on tRNA pairs with which mRNA codon?

  • A. UAC
  • B. AUG
  • C. GUA
  • D. ATG

Answer: B. AUG

Explanation: Anticodon UAC pairs complementarily with the start codon AUG on mRNA during translation.

5. Which type of joint is present between the atlas and the axis vertebrae?

  • A. Hinge joint
  • B. Pivot joint
  • C. Ball and socket joint
  • D. Saddle joint

Answer: B. Pivot joint

Explanation: The atlanto-axial joint is a pivot joint that allows rotation of the head from side to side.

6. Which scientist demonstrated that DNA, and not protein, is the genetic material using bacteriophages?

  • A. Griffith
  • B. Meselson and Stahl
  • C. Hershey and Chase
  • D. Avery and MacLeod

Answer: C. Hershey and Chase

Explanation: Hershey and Chase used radioactive phosphorus (³²P) and sulfur (³⁵S) to prove that DNA is the hereditary material in bacteriophages.

7. Which phase of the cell cycle is known as the quiescent stage, where cells remain metabolically active but do not divide?

  • A. G₁ phase
  • B. G₂ phase
  • C. S phase
  • D. G₀ phase

Answer: D. G₀ phase

Explanation: Cells in the G₀ phase remain metabolically active but exit the normal cell cycle and do not undergo division.

8. Which of the following is an example of an amphibian?

  • A. Salamander
  • B. Lizard
  • C. Crocodile
  • D. Turtle

Answer: A. Salamander

Explanation: Salamanders belong to Class Amphibia and typically live both in water and on land during different stages of their life cycle.

9. Which plant tissue is mainly responsible for the transport of food from leaves to other parts of the plant?

  • A. Xylem
  • B. Phloem
  • C. Cambium
  • D. Epidermis

Answer: B. Phloem

Explanation: Phloem transports sugars and other organic nutrients produced during photosynthesis from source tissues to sink tissues.

10. Deficiency of which mineral nutrient in plants commonly results in chlorosis due to reduced chlorophyll synthesis?

  • A. Potassium
  • B. Iron
  • C. Calcium
  • D. Sulfur

Answer: B. Iron

Explanation: Iron is essential for chlorophyll synthesis. Its deficiency commonly causes interveinal chlorosis, especially in young leaves.