Identify the correct statement about genetic drift: MCQ with Answer and Explanation

Explanation:
PCR involves repeated cycles of high-temperature denaturation (around 94°C) to separate the DNA strands. Normal DNA polymerases would be destroyed at these temperatures. Therefore, a thermostable DNA polymerase is required. Taq polymerase, isolated from the thermophilic bacterium Thermus aquaticus found in hot springs, is the most commonly used enzyme because it can withstand the high denaturation temperatures without losing its activity, eliminating the need to add fresh enzyme after each cycle.

Explanation:
Meristem culture, a type of tissue culture, involves excising the virus-free apical meristem (shoot tip) and growing it on a nutrient medium to produce a whole plant free of viruses. This is because meristematic cells lack vascular connections through which viruses spread. Cloning produces identical copies, hybridization crosses varieties, mutagenesis uses mutagens.

Explanation:
Gibberellins stimulate the synthesis of hydrolytic enzymes (e.g., amylase) that mobilize stored food reserves, promoting germination. Abscisic acid induces and maintains dormancy. Ethylene promotes ripening, auxin cell elongation.