In fish farming, 'induced breeding' is commonly achieved by injecting: MCQ with Answer and Explanation

Explanation:
Vasoactive Intestinal Peptide (VIP) is a 28-amino acid neuropeptide that acts as a neurotransmitter and a hormone. In the gastrointestinal tract, its primary functions are stimulatory and relaxant: it stimulates the secretion of water and electrolytes into the intestinal lumen (acting as a secretagogue), relaxes the smooth muscle of the gut (including the lower esophageal sphincter, stomach, and gall bladder), and stimulates the pancreas to secrete a bicarbonate-rich juice. It also causes vasodilation in the gut. Excessive VIP secretion can lead to severe watery diarrhea (as in VIPoma).

Explanation:
The plasma membrane is selectively permeable, regulating the entry and exit of specific molecules into and out of the cell. Lysosomes are membrane-bound organelles containing powerful hydrolytic (digestive) enzymes for intracellular digestion. The nucleolus is the site of ribosomal RNA (rRNA) synthesis and ribosome assembly, not protein synthesis, which occurs at ribosomes. Thus, statements 1 and 3 are correct.

Explanation:
Iodine deficiency impairs thyroid hormone synthesis, leading to elevated TSH and enlargement of the thyroid gland (goiter). Iodized salt prevents it.