Question 43

Urea is excreted by 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 it is excreted by sweat glands as part of the body's method for eliminating excess nitrogen. This process helps maintain the body's nitrogen balance.

A) Water

Water is primarily excreted through sweat for thermoregulation rather than as a waste product from protein breakdown. While it is a major component of sweat, it does not specifically result from the metabolic process of protein degradation.

B) Lysozymes

Lysozymes are enzymes that break down bacterial cell walls and are found in various body fluids, including sweat. However, they are not excreted in response to protein breakdown and ammonia formation, making this option incorrect in the context of the question.

C) Urea

Urea is indeed the correct answer as it is produced when proteins are metabolized, leading to the formation of ammonia. The liver converts ammonia to urea, which is then excreted through sweat glands, making it a waste product directly linked to protein catabolism.

D) Sebum

Sebum is an oily substance produced by sebaceous glands to lubricate and protect the skin. It is not a waste product formed from protein breakdown nor is it excreted by sweat glands, thus making this option irrelevant to the question.

Conclusion

Urea is the only substance listed that is specifically related to the breakdown of proteins and the formation of ammonia, thus highlighting its role in nitrogen excretion through sweat. The other options either serve different functions or are unrelated to the metabolic processes described, confirming that urea is the definitive correct answer.