Which of the following statements about the human reproductive system is correct? MCQ with Answer and Explanation

Explanation:
Blood group O lacks A and B antigens on red cells but contains both anti-A and anti-B antibodies in plasma. This makes it the universal donor for packed red cells but dangerous plasma donor. Group AB has no antibodies. So, the presence of both antibodies is correct.

Explanation:
Insulin, from beta cells, lowers blood glucose by stimulating glucose uptake into muscle and adipose tissue (via GLUT4) and promoting glycogenesis. Glucagon, cortisol, and GH raise blood glucose. Insulin is the only hormone that significantly lowers blood glucose.

Explanation:
The Miller-Urey experiment (1953) simulated the conditions of the primitive Earth's atmosphere (methane, ammonia, hydrogen, and water vapor) in a closed system and applied electrical sparks to simulate lightning. After a week, they found that several organic compounds, including amino acids (the building blocks of proteins), had been synthesized, supporting the theory of chemical evolution.