The structure that allows the exchange of gases and nutrients between the mother and fetus is the: MCQ with Answer and Explanation

Explanation:
Beriberi is a disease affecting the nervous and cardiovascular systems due to lack of thiamine (B₁). Scurvy is vitamin C deficiency, pellagra is niacin (B₃), rickets is vitamin D. Thiamine is a coenzyme in carbohydrate metabolism.

Explanation:
Pancreatic Polypeptide (PP) is a hormone secreted by the F cells (also known as gamma cells), which are scattered throughout the islets of Langerhans in the pancreas, primarily in the head of the pancreas. Its secretion is stimulated by the ingestion of a meal, particularly one rich in protein. Its primary functions are inhibitory: it inhibits the secretion of pancreatic digestive enzymes, inhibits gall bladder contraction, and slows down gastric emptying. It is thought to regulate the rate of nutrient absorption and prevent over-digestion.

Explanation:
Auxin produced at the shoot apex inhibits lateral bud growth, a phenomenon called apical dominance. Removing the tip promotes branching.