The element that is a component of hemoglobin is: MCQ with Answer and Explanation

Explanation:
Retinal (vitamin A aldehyde) is part of rhodopsin and cone pigments. Deficiency causes night blindness and xerophthalmia.

Explanation:
Fibroblast Growth Factor 21 (FGF21) is a hormone primarily secreted by the liver (and to a lesser extent by adipose tissue and pancreas) in response to metabolic stresses like fasting, a high-carbohydrate diet, or mitochondrial dysfunction. Its primary functions are to regulate glucose and lipid metabolism. It improves insulin sensitivity, promotes the uptake of glucose by adipose tissue, stimulates the breakdown of fats (lipolysis) and ketogenesis in the liver, and reduces triglyceride levels. It is considered a 'starvation hormone' and a potential therapeutic target for metabolic diseases like diabetes and obesity.

Explanation:
In 1953, Stanley Miller and Harold Urey conducted an experiment to test the Oparin-Haldane hypothesis of chemical evolution. They simulated the reducing atmosphere of primitive Earth, which they believed lacked free oxygen. The gas mixture used was methane (CH4), ammonia (NH3), hydrogen (H2), and water vapor (H2O). By applying electrical sparks (simulating lightning), they successfully synthesized amino acids and other organic compounds.