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

Explanation:
The kidneys are the primary excretory organs, filtering blood through nephrons to remove waste products and excess water, forming urine. The liver is a multifunctional organ that produces bile, which is stored in the gall bladder and released into the small intestine to emulsify fats, aiding in their digestion. The spleen is a lymphoid organ involved in filtering blood and immune responses; it does not produce digestive enzymes (the pancreas does). Thus, statements 1 and 2 are correct.

Explanation:
The Bohr effect describes how an increase in the partial pressure of CO2 (pCO2) or a decrease in pH (increase in H+ concentration) reduces hemoglobin's affinity for oxygen, shifting the oxygen dissociation curve to the right. This facilitates the unloading of oxygen in metabolically active tissues where CO2 and acid levels are high. The reverse occurs in the lungs, enhancing oxygen loading.

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.