Question

Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R
Assertion A : Phytoplasma is a motile bacterium
Reason R : Phytoplasma is transmitted by leaf hopper
In light of the above statements, choose the correct answer from the options given below

• A. Both A and R are true and R is the correct explanation of A
• B. Both A and R are true but R is NOT the correct explanation of A
• C. A is true but R is false
• D. A is false but R is true

Hint:

Phytoplasma = "Phloem-limited, wall-less, non-motile, insect-vectored".
Common diseases: Little leaf of Brinjal, Sesame phyllody.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
The question asks for the fundamental biological characteristics and transmission methods of Phytoplasmas, which are unique plant pathogens.

Step 2: Detailed Explanation:

• Assertion Analysis: Phytoplasmas are specialized bacteria that lack a cell wall (belonging to the class Mollicutes). They are pleomorphic (can change shape) and reside exclusively in the phloem of plants.
Crucially, Phytoplasmas lack flagella and are entirely non-motile. They move through the plant solely via the bulk flow of phloem sap.
Therefore, Assertion A is False.

• Reason Analysis: Because they are confined to the phloem and lack a cell wall (making them fragile outside the host), they cannot survive in soil or water.
They rely on insect vectors that feed on phloem sap for transmission between plants.
The most common vectors are Leafhoppers (Cicadellidae) and planthoppers.
Therefore, Reason R is True.
Final Answer:
Phytoplasmas are non-motile prokaryotes transmitted primarily by leafhoppers. This makes the assertion false and the reason true.