The enzyme that catalyzes the synthesis of cAMP from ATP is: MCQ with Answer and Explanation

The enzyme that catalyzes the synthesis of cAMP from ATP is:
A. Adenylyl cyclase
B. Phospholipase C
C. Protein kinase A
D. Guanylyl cyclase
Answer: Option A
Solution (By JKSSB Mock Tests)
Adenylyl cyclase converts ATP to cyclic AMP, a second messenger. Guanylyl cyclase makes cGMP, phospholipase C produces IP₃/DAG, PKA is activated by cAMP.

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Practice More Biology Questions

Question #1
Which of the following is a characteristic of mitosis but NOT meiosis?
A. Production of genetically identical daughter cells
B. Crossing over
C. Pairing of homologous chromosomes
D. Formation of haploid gametes

Correct Answer: Option A


Explanation:
Mitosis produces two genetically identical diploid daughter cells (clones) essential for growth, repair, and asexual reproduction. Meiosis involves pairing (synapsis) and crossing over during prophase I, and produces four genetically diverse haploid cells (gametes). The conservation of chromosome number and genetic identity is a hallmark of mitosis.

This question belongs to: Science Biology
Question #2
Consider statements about human diseases: 1. Tuberculosis is caused by a virus. 2. Polio is caused by a bacterium. 3. Tetanus affects the nervous system. Which are correct?
A. 1 and 2 only
B. 1, 2 and 3
C. 2 and 3 only
D. 3 only

Correct Answer: Option D


Explanation:
Tuberculosis is a bacterial disease caused by Mycobacterium tuberculosis, primarily affecting the lungs. Polio is a viral disease caused by the poliovirus, attacking the nervous system. Tetanus is caused by the bacterium Clostridium tetani, which produces a neurotoxin that causes severe muscle spasms and affects the nervous system. Thus, only statement 3 is correct.

This question belongs to: Science Biology
Question #3
Deficiency of which vitamin causes night blindness?
A. Vitamin C
B. Vitamin D
C. Vitamin A
D. Vitamin B₁

Correct Answer: Option C


Explanation:
Vitamin A (retinol) is essential for the synthesis of rhodopsin, the visual pigment in rod cells responsible for low-light vision. Deficiency leads to night blindness (nyctalopia) and, if severe, xerophthalmia and permanent blindness. Vitamin B₁ deficiency causes beriberi, C scurvy, D rickets.

This question belongs to: Science Biology