The hormone that stimulates the release of growth hormone from the pituitary is:
A. Growth hormone-releasing hormone (GHRH)
B. Dopamine
C. Cortisol
D. Somatostatin
Answer: Option A
Solution (By JKSSB Mock Tests)
GHRH, from the hypothalamus, stimulates the anterior pituitary to secrete growth hormone. Somatostatin inhibits GH release. Dopamine inhibits prolactin.
Explanation:
Abscisic acid (ABA) is known as the stress hormone because it plays a crucial role in plant responses to environmental stresses, particularly drought. It induces the closure of stomata to reduce water loss (transpiration) and also inhibits seed germination and growth, helping the plant survive adverse conditions.
Explanation:
Vitamin C is a cofactor for prolyl and lysyl hydroxylases, enzymes essential for collagen cross-linking and stability. Deficiency impairs wound healing and causes scurvy. Vitamin A is for epithelial integrity.
Explanation:
Mitochondria produce ATP through oxidative phosphorylation in the inner membrane. They are double-membrane organelles with their own DNA (mtDNA) and 70S ribosomes, supporting the endosymbiotic theory. The Krebs cycle occurs in the mitochondrial matrix. Nucleus controls cell activities, ribosomes synthesize proteins, Golgi apparatus packages and modifies proteins. Mitochondria are abundant in energy-demanding cells like muscle cells.
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