The molecule that acts as a second messenger in many hormone signaling pathways is:
A. DNA
B. ATP
C. Glucose
D. cAMP
Answer: Option D
Solution (By JKSSB Mock Tests)
Cyclic adenosine monophosphate (cAMP) is a common intracellular second messenger produced by adenylyl cyclase upon hormone receptor activation (e.g., glucagon, adrenaline). It activates protein kinase A, triggering a cascade of cellular responses. Other second messengers include IP₃, DAG, Ca²⁺.
Explanation:
Innate (natural) immunity is non-specific, present at birth, and provides the first line of defense. It includes physical barriers (skin), phagocytes, and chemical defenses. Adaptive immunity is acquired and specific.
Consider the following statements about hormones:
1. Insulin is a peptide hormone.
2. Thyroxine is an amino acid derivative.
3. Cortisol is a steroid hormone.
Which of the above is/are correct?
Explanation:
Oxytocin, released from the posterior pituitary, increases the frequency and strength of uterine contractions during labor via positive feedback. Prolactin stimulates milk production, estrogen helps uterine growth, relaxin relaxes pelvic ligaments.
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