Question

The chief nitrogenous waste in mammals is

• A. ammonia
• B. urea
• C. uric acids
• D. amino acids

Answer 1

The correct option is B

urea

Explanation of the correct option:

The correct option is B:

1. Excretion is the process by which harmful nitrogenous wastes are removed from the body.
2. The nitrogenous wastes include mostly metabolic wastes.
3. The organisms are divided into three categories based on the nitrogenous wastes excreted by them - ammonotelic, ureotelic, and uricotelic.
4. The organisms which release urea as their excretory product are called ureotelic.
5. The mammals are called ureotelic as they release urea as their excretory product.

Explanation of the incorrect options:

Option A:

1. The organisms which release ammonia as their excretory product are called ammonotelic.
2. Examples are fish and aquatic amphibians.

Option C:

1. The organisms which release uric acid as their excretory product are called uricotelic.
2. Examples are birds, reptiles, etc.

Option D:

1. The molecules of which protein is made up are called amino acids.
2. Excretory products contain amino acids, but no organisms release amino acids as their excretory product.