The 'Cortical reaction' in the ovum, which prevents polyspermy (entry of multiple sperm), is triggered by: MCQ with Answer and Explanation

Explanation:
A biological species is defined as a group of potentially interbreeding natural populations that are reproductively isolated from other such groups and produce fertile offspring. Physical similarity or shared habitat does not guarantee species status, as reproductive isolation is the key criterion.

Explanation:
Ethylene is a gaseous plant hormone that promotes fruit ripening (climacteric fruits like banana, apple), leaf abscission, and senescence. Auxin, gibberellin, and cytokinin primarily promote growth. Ethylene is used commercially to ripen fruits uniformly. It also stimulates the formation of abscission layers and inhibits stem elongation.

Explanation:
Gene therapy is an experimental technique that involves introducing genes into a patient's cells to correct or compensate for genetic defects causing disease. Transgenic animals have had their genome deliberately altered by the insertion of foreign DNA from another species. Biopesticides, derived from natural materials like bacteria, plants, or minerals, are generally target-specific and non-toxic to humans and the environment, unlike synthetic chemical pesticides. Thus, statements 1 and 2 are correct.