Question 39

Urea is excreted by the sweat glands in response to the breakdown of proteins and the formation of ammonia.

Urea is a waste product formed from the breakdown of proteins and is excreted by the sweat glands as a means of eliminating excess nitrogen from the body.

A) Lysozymes

Lysozymes are enzymes that break down bacterial cell walls and are not involved in the excretion process related to protein breakdown or ammonia formation. They are primarily found in bodily fluids such as saliva and tears, not in sweat.

B) Water

While water is a major component of sweat and is excreted to help regulate body temperature, it is not a waste product of protein breakdown. Therefore, it does not relate to the question of substances excreted specifically due to protein metabolism.

C) Urea

Urea is indeed the correct answer as it is produced in the liver from ammonia, which is a byproduct of protein metabolism. The kidneys filter urea from the blood, and a small amount can also be excreted through sweat glands, making it directly relevant to the question.

D) Sebum

Sebum is an oily substance produced by sebaceous glands to lubricate and protect the skin. It is not related to the breakdown of proteins or the formation of ammonia, and thus, it does not pertain to the excretion process described in the question.

Conclusion

Urea is the correct answer as it is specifically linked to the metabolic process involving protein breakdown and ammonia formation. All other options either do not relate to this metabolic pathway or do not involve the excretion process through sweat glands, confirming urea's unique role in this context.