The blood vessel that has valves to prevent backflow is: MCQ with Answer and Explanation

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:
Sewage contains organic matter that can be broken down by microorganisms, hence biodegradable. DDT, plastics, and mercury are non-biodegradable, persisting in the environment and accumulating in food chains (biomagnification). Biodegradable pollutants can be decomposed naturally, reducing long-term harm, but excessive loads can cause eutrophication. Non-biodegradable pollutants require special disposal and cause lasting ecological damage.

Explanation:
Guttation is the exudation of water in liquid form from the intact, uninjured surfaces of plants, typically from the margins or tips of leaves. This occurs when root pressure is high (usually at night or early morning when transpiration is low and soil moisture is high) and the rate of water absorption exceeds the rate of transpiration. The water is forced out through specialized structures called hydathodes (or water stomata), which are located at the leaf margins and lack the mechanism to close like regular stomata.