Question 38

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 a means of removing excess nitrogen from the body.

A) Sebum

Sebum is an oily substance produced by sebaceous glands, primarily responsible for lubricating the skin and hair. It is not a waste product of protein breakdown and does not play a role in the excretion of ammonia.

B) Water

Water is a major component of sweat and is primarily excreted to regulate body temperature through evaporation. While it is important for maintaining hydration and thermoregulation, it does not specifically result from the breakdown of proteins or the formation of ammonia.

C) Urea

Urea is the correct answer as it is produced in the liver from ammonia, a byproduct of protein metabolism. It is then excreted through sweat glands, particularly when the body needs to eliminate excess nitrogen.

D) Lysozymes

Lysozymes are enzymes found in various body fluids, including sweat, that help combat bacterial infections. However, they are not related to the metabolic breakdown of proteins or the formation of ammonia, thus making them irrelevant to the question.

Conclusion

Urea is the only substance listed that is directly associated with the breakdown of proteins and the excretion of ammonia through sweat glands. Other options such as sebum, water, and lysozymes serve different biological functions and do not pertain to the metabolic process highlighted in the question. Therefore, urea stands out as the definitive answer.