Question

A. Necrosis manifest in the form of blotch
B. Abnormal growth manifest in the form of warts
C. Necrosis manifest in the form of leaf curl
D. Abnormal growth manifest in the form of anthracnose
E. Witche's broom is caused only by phytoplasma
Choose the correct answer from the options given below:

• A. A and B only
• B. C and D only
• C. D and E only
• D. C and E only

Hint:

Avoid extreme words like "only" in biological statements. Since Witches' broom can also be caused by fungi, viruses, or mites, statement E is false. This helps eliminate three out of four options.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Plant disease symptoms are classified into major categories based on cellular effects:
Necrosis is the death of host cells and tissues.
Abnormal growth (hypertrophy and hyperplasia) refers to excessive cell enlargement or cell division, leading to distortion or overgrowths.

Step 2: Detailed Explanation:
Let us analyze each statement:
Statement A: A blotch is a large, irregular, necrotic area on leaves or stems.
Because it represents dead tissue, it is a manifestation of necrosis. Thus, Statement A is correct.
Statement B: Warts (such as those caused by Synchytrium endobioticum in potato) are localized, tumor-like outgrowths resulting from excessive cell division (hyperplasia) and cell enlargement (hypertrophy).
This is a form of abnormal growth. Thus, Statement B is correct.
Statement C: Leaf curl involves curling, puckering, and distortion of leaves caused by uneven cell division rates in different leaf regions.
This is a hypertrophic/growth-distortion symptom, not necrosis. Thus, Statement C is incorrect.
Statement D: Anthracnose is characterized by dark, sunken, necrotic lesions on leaves, stems, or fruits.
It represents cell death (necrosis), not abnormal growth. Thus, Statement D is incorrect.
Statement E: Witches' broom is an abnormal proliferation of shoots caused by a loss of apical dominance.
While it is commonly caused by phytoplasmas, it can also be induced by other pathogens, including fungi (such as Taphrina deformans or Crinipellis perniciosa) or viruses. Thus, stating it is caused only by phytoplasmas is incorrect.

Step 3: Final Answer:
Only statements A and B are correct. Therefore, the correct option is (A).