How does a nursing infant receive antibodies from its mother?

Correct Answer: B

Rationale: A nursing infant receives antibodies from its mother through the absorption of antibodies present in breast milk. Choice A is incorrect as anabolism and catabolism refer to metabolic processes, not the transfer of antibodies. Choice C is incorrect as the infant does not need to synthesize antibodies but directly receives them. Choice D is incorrect because while genetic inheritance plays a role in the immune system, in this case, the direct transfer of antibodies occurs through breast milk.

Correct Answer: A

Rationale: The correct answer is 'tissue and plasma.' Protein turnover involves the continuous exchange of proteins between body tissues and the bloodstream (plasma) as part of normal metabolic processes. This process ensures a balance in protein levels throughout the body. Choices B, C, and D are incorrect as they do not represent the primary sites for protein turnover in the body.

Correct Answer: B

Rationale: The correct answer is B: Intestinal mucosa. The intestinal mucosa has the highest rate of protein turnover due to its rapid cell renewal. The skin, muscle, and adipose tissue do not exhibit protein turnover rates as high as the intestinal mucosa. Skin cells turnover relatively slower compared to the rapid renewal of intestinal mucosa cells. Muscles have a moderate rate of protein turnover, while adipose tissue has a lower turnover rate compared to the other tissues mentioned.

Correct Answer: C

Rationale: Anabolism is the phase of metabolism responsible for building up and repairing tissues in the body. It involves processes that require energy to synthesize complex molecules from simpler ones. Digestion (choice A) is the process of breaking down food into simpler substances for absorption. Catabolism (choice B) involves the breakdown of complex molecules into simpler ones with the release of energy. Ketosis (choice D) is a metabolic state where the body uses fat as the primary source of energy, which is not directly related to growth and repair.

Correct Answer: D

Rationale: Negative nitrogen balance occurs when the body loses more nitrogen than it gains. This imbalance is often seen in conditions like anorexia in older adults, where insufficient protein intake leads to muscle breakdown and negative nitrogen balance. Choices A, B, and C do not typically lead to negative nitrogen balance as seen in anorexia in older adults.