Question

The organisms attached to the substratum, generally, possess

• A. one single opening of the digestive canal
• B. cilia on the surface to create water current
• C. radial symmetry
• D. asymmetrical body.

Answer 1

The Correct Option is C

To determine the characteristic of organisms attached to the substratum, we need to consider their typical biological features. Organisms that are stationary and attached to a surface often need a body plan that allows them to interact with the environment from all sides.

Here's a breakdown of the options provided:

• One single opening of the digestive canal: This refers to an incomplete digestive system where the organism has a single opening serving both as mouth and anus, which is not exclusive to sessile organisms.
• Cilia on the surface to create water current: While some sessile aquatic organisms use cilia to draw in food particles, this feature is not universal to all attached organisms.
• Radial symmetry: Radial symmetry is a common characteristic of organisms that are attached to the substratum. It allows them to interact with the environment from all directions. This type of symmetry is well-suited for sessile organisms that need to access food and other resources coming from any direction. Examples include starfish and sea anemones.
• Asymmetrical body: Asymmetry is less common and does not specifically aid sessile living.

Based on the characteristics mentioned and general biological understanding, the correct answer is radial symmetry. This configuration is advantageous as it offers increased surface interaction with the environment, a typical need for organisms that do not move from their place.