The vitamin that is a coenzyme in the decarboxylation of pyruvate to acetyl-CoA is: MCQ with Answer and Explanation

Explanation:
In roots, the protoxylem (first formed xylem) lies towards the periphery and metaxylem towards the centre; this arrangement is called exarch. In stems, protoxylem is towards the centre, called endarch. Exarch condition is typical of roots. Mesarch is found in ferns. This arrangement aids in understanding anatomical differences between root and stem.

Explanation:
Lichens are a mutualistic association between an alga (or cyanobacterium) and a fungus. The alga photosynthesizes, providing food; the fungus provides shelter, water, and minerals. Both benefit. Tapeworm is parasitism, barnacles on whales commensalism (or sometimes parasitism depending on effect), mosquito blood-sucking is parasitism.

Explanation:
Ghrelin is a peptide hormone produced mainly by the endocrine cells of the stomach, especially when it is empty. It is often called the 'hunger hormone' because it acts on the arcuate nucleus of the hypothalamus to stimulate appetite (orexigenic effect) and promote food intake. Ghrelin levels rise before meals and fall after eating. It has the opposite effect of leptin, which suppresses appetite.