Question

In which of the following organisms, cell wall is not found in any stage?

• A. Dinoflagellates
• B. Chrysophytes
• C. Slime moulds
• D. Protozoans

Hint:

Organisms can be classified based on the presence or absence of a cell wall:
- Plants, fungi, and most algae have a cell wall.
- Protozoans lack a cell wall completely, making them more flexible and mobile.
- Slime moulds temporarily develop a cell wall in their spore stage.

Answer 1

The Correct Option is D

Step 1: Understanding Cell Wall in Different Organisms Cell walls are structural components found in many organisms, providing support and protection. However, certain organisms lack a cell wall at all stages of their life cycle. - Dinoflagellates: Most have a cell wall composed of cellulose plates, though some may lack it. 
- Chrysophytes: They generally possess a siliceous (silica-based) cell wall. 
- Slime Moulds: These have a cell wall during the spore-forming stage, though they may be absent in the vegetative phase. 
- Protozoans: These are unicellular eukaryotic organisms that completely lack a cell wall in all life stages. They have a flexible plasma membrane instead.
Step 2: Identifying the Correct Answer Since protozoans never possess a cell wall at any stage of their life cycle, the correct answer is Option (4) Protozoans. 

Step 3: Verifying the Options - Option (1) Dinoflagellates (Incorrect – Many have cellulose cell walls) 
- Option (2) Chrysophytes (Incorrect – Have silica-based cell walls) 
- Option (3) Slime moulds (Incorrect – Have cell walls during spore formation)
- Option (4) Protozoans (Correct – No cell wall at any stage) 
Thus, the correct answer is (4) Protozoans.