Which of the following is an auto-immune disease? MCQ with Answer and Explanation

Explanation:
Vitamin A is essential for the synthesis of rhodopsin. Deficiency leads to impaired dark adaptation (night blindness) and eventually xerophthalmia. Beri-beri is B₁ deficiency, pellagra B₃, scurvy vitamin C.

Explanation:
The Foramen of Panizza is a small opening located between the left and right aortic arches at the base of the heart in crocodilians (crocodiles, alligators). It allows blood to flow between the two systemic arches. During diving, when pulmonary resistance increases, this foramen allows deoxygenated blood to bypass the lungs and enter the systemic circulation, conserving oxygen for vital organs. Frogs have a three-chambered heart without this specific foramen.

Explanation:
Cytokinins are plant hormones that primarily promote cell division (cytokinesis) in the presence of auxins. They are also crucial in delaying senescence (aging) of leaves by helping to maintain protein and nucleic acid content, a phenomenon known as the Richmond-Lang effect. They are synthesized mainly in root apices.