Tag: zoology

The major excretory products are carbon dioxide, excess water, and nitrogenous compounds like ammonia, urea, uric acid, etc. Carbon dioxide and water are produced in the process of tissue respiration. Nitrogenous compounds are formed from the breakdown of proteins and amino acids. So, the correct option is "B" (Mineral salt).

Ammonia was the first and simplest excretory substance in the animal body and is excreted as it is toxic. It requires large amounts of water for its excretion and so it is seen in most aquatic vertebrates and invertebrates.

A) Perspiration (sweating) is the loss of water and salts through the surface of the skin. This water evaporates. Urine is mostly water and is also composed of salts and is excreted by the animal into the environment. While breathing, minute molecules of water or water vapour are given out into the environment along with carbon dioxide.

Organisms can store their wastes in different glands and organs such as the kidneys, sweat glands, lungs etc. All the nitrogenous and solid wastes are stored by different organisms for a certain period in certain body organs such as the kidneys and the intestines, after which they are eliminated from the body. So, the correct option is 'True'.

Earthworms excrete ammonia when sufficient water is available, because a large volume of water is needed by the animal to dissolve ammonia and eliminate it from, the body. Whereas in drier environment the animal eliminates urea as it requires only considerable amount of water for the excretion of urea because urea is very soluble in water.

The end products of aerobic metabolism of carbohydrates are carbon dioxide and water. Carbon dioxide remains dissolved in the blood and is carried by the veins to the lungs for oxygenation. If carbon dioxide is not removed from the metabolizing tissues, it will be toxic for that tissue and stop metabolism.

Urea is both osmoregulator as well as nitrogenous waste. Urea is produced in the liver and excreted through urine. The urea helps in osmoregulation by participating in counter current system, small amounts of urea enter the thin segment of the ascending limb of Henle’s loop which is transported back to the interstitium by the collecting tubule.  

The excretory product of spider is guanine. It is formed as a result of nucleotide metabolism. It does not require water for elimination because it is less soluble than uric acid and helps to conserve more water.