Question

Almost all the aquatic animals excrete ammonia as the nitrogenous waste product. Which of the following statements is not in agreement with this situation? (a) Ammonia is easily soluble in water. (b) Ammonia is released from the body in a gaseous state. (c) Ammonia is highly toxic and needs to be eliminated when formed. (d) Both (a) and (b).

Short answer

Statement (b) 'Ammonia is released from the body in a gaseous state.' is not in agreement with the situation.

Step-by-step solution

Understanding the Concept

Know that aquatic animals generally excrete ammonia because it is highly soluble in water, allowing them to easily eliminate it. Ammonia is also highly toxic, so it is important for animals to eliminate it quickly.

Analyzing the Statements

Review each statement to determine if it aligns with the concept that ammonia is the primary nitrogenous waste in aquatic animals.

Identifying the Incorrect Statement

Determine which statement is not consistent with the properties of ammonia as a waste product in aquatic animals.

Key concepts

Ammonia Toxicity

Ammonia is a nitrogen-containing compound that is a byproduct of the metabolism of proteins. In the physiological context, ammonia toxicity refers to the harmful effects that occur when the concentration of ammonia in an organism's body becomes too high.

Ammonia is particularly toxic to cells because it can interfere with cellular function and pH balance. At elevated levels, ammonia can disrupt neurological processes, leading to issues like disorientation, muscle weakness, and in severe cases, coma or death. Aquatic animals, due to their aqueous environment, are exposed to ammonia not only from their own excretion but also from their surroundings.

To avoid toxicity, these animals have evolved efficient excretory systems that quickly convert ammonia to less harmful substances, or directly excrete it into the surrounding water. This rapid expulsion is crucial since their watery environment could easily become saturated with ammonia, leading to increased toxicity.

Nitrogenous Waste Products

All living organisms generate waste products that must be eliminated to maintain homeostasis. Nitrogenous waste products are a significant group of wastes generated from the breakdown of proteins and nucleic acids.

The primary nitrogenous wastes are ammonia, urea, and uric acid. Ammonia, the focus for many aquatic animals, is produced by the deamination of amino acids. Urea, which is less toxic and more water-soluble than ammonia, is produced in the liver of mammals and some fish through the urea cycle. Uric acid is the least soluble but least toxic waste product and is predominantly excreted by reptiles, birds, and insects.

Aquatic animals tend to excrete ammonia directly due to its high solubility in water. This method of excretion is highly energy efficient, which is important in the aquatic environment where energy conservation is crucial.

Ammonia Solubility

The solubility of a substance is a measure of how well it can dissolve in a solvent at a given temperature and pressure.

Ammonia is highly soluble in water, which is why it is the primary nitrogenous waste product for many aquatic animals. The high solubility facilitates its excretion as it quickly dissolves in the surrounding water and is eliminated from the animal's body. This quick diffusion into the water column prevents the accumulation of ammonia to toxic levels within the organism's tissues.

Furthermore, the fact that these animals live in water means that the diluted ammonia can be dispersed into a large volume, lowering its concentration to non-toxic levels. This natural property of ammonia's solubility is what allows aquatic animals to effectively manage their nitrogenous waste through their excretory systems.