The functional unit of the kidney is: MCQ with Answer and Explanation

Explanation:
While restriction enzymes were first observed by Linn and Arber, the first Type II restriction endonuclease (HindII), which is the type used in genetic engineering because it cuts at specific recognition sites, was isolated and characterized by Hamilton O. Smith, Kent W. Wilcox, and Thomas J. Kelly in 1970 from Haemophilus influenzae. For this discovery, Smith shared the Nobel Prize in Physiology or Medicine in 1978. Kary Mullis invented PCR.

Explanation:
Polygenic inheritance is when multiple genes (polygenes) contribute to a single trait, resulting in continuous variation. Human skin color is controlled by at least three genes, showing a spectrum of phenotypes. Pleiotropy is one gene affecting multiple traits. Multiple alleles refer to more than two alleles for a gene (e.g., ABO blood groups). Co-dominance is when both alleles express equally.

Explanation:
The pollen grain contains the male gametophyte, which produces two sperm cells. The ovule contains the female gametophyte (embryo sac). Endosperm is the triploid nutritive tissue formed after double fertilization.