Question

In Hydra, waste material of food digestion and nitrogenous waste material are removed respectively from

• A. mouth and mouth
• B. body wall and body wall
• C. mouth and body wall
• D. mouth and tentacles.

Answer 1

The Correct Option is C

The question pertains to the biological processes of excretion in Hydra, a simple, multicellular aquatic organism. To address the question, let's explore how waste products are expelled in Hydra, which belongs to the phylum Cnidaria.

In Hydra, waste material from food digestion and nitrogenous waste are expelled in the following ways:

• Food Digestion Waste: Hydra has a simple gastrovascular cavity, which serves both digestive and circulatory functions. The mouth is the only opening in the body of Hydra that functions for both ingestion and egestion. After digestion, any undigested food is expelled through the mouth.
• Nitrogenous Waste: Like other simple aquatic animals, Hydra excretes nitrogenous wastes such as ammonia directly through diffusion across its body wall. This is a common method in organisms that live in aquatic environments with a high surface area to volume ratio.

Therefore, the correct answer is: mouth and body wall. The mouth is responsible for expelling undigested food particles, while nitrogenous wastes are diffused across the body wall.

Let's evaluate the given options to elucidate why the correct answer fits:

• Option 1: mouth and mouth - Incorrect, because nitrogenous waste is not expelled through the mouth but through the body wall.
• Option 2: body wall and body wall - Incorrect, since the body wall is not used for expelling undigested food; it diffuses nitrogenous waste.
• Option 3: mouth and body wall - Correct, as per the explanation above.
• Option 4: mouth and tentacles - Incorrect, because tentacles are involved in capturing prey, not in waste expulsion.

This analysis confirms the biological processes in Hydra that lead to choosing "mouth and body wall" as the correct answer.