Monocot stems have numerous vascular bundles scattered in the ground tissue. They are closed (lack cambium), collateral, and hence do not undergo secondary growth. Dicot stems have vascular bundles arranged in a ring, open (with cambium) allowing secondary growth. Radial vascular bundles are characteristic of roots. Scattered bundles are a key identifying feature of monocots.
Explanation:
Due to the rigid cell wall, plant cells form a cell plate at the equator, which develops into a new cell wall separating daughter cells. Animal cells form a cleavage furrow.
Explanation:
Zinc is a micronutrient that acts as a cofactor for tryptophan synthetase, an enzyme involved in the biosynthesis of the auxin indole-3-acetic acid (IAA) from tryptophan. Zinc deficiency causes stunted growth and 'little leaf' disease. Iron is for chlorophyll synthesis, copper for enzymes, manganese for photosystem II.
Explanation:
Glucagon, released by pancreatic alpha cells when blood glucose is low, activates glycogen phosphorylase, leading to glycogenolysis and release of glucose from the liver. Insulin promotes glycogenesis. Cortisol and thyroxine have permissive effects.
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