Which of the following defines a biological species? MCQ with Answer and Explanation

Explanation:
Primase is an RNA polymerase that synthesizes short RNA primers complementary to the DNA template, providing a free 3'-OH for DNA polymerase to begin synthesis. Helicase unwinds, polymerase extends, ligase joins.

Explanation:
Industrial melanism is a classic example of natural selection in action. Before the industrial revolution, light-colored moths were more common as they blended with lichen-covered trees, avoiding predators. Pollution killed the lichen and darkened the trees, making dark-colored (melanic) moths better camouflaged. The population shifted to predominantly dark moths, demonstrating survival of the fittest.

Explanation:
Rhodopsin (visual purple) in rod cells of the retina consists of opsin and retinal (derived from vitamin A). It bleaches in light, triggering nerve impulses. It is highly sensitive, enabling night vision. Iodopsin is in cones for color vision.