Question

Assertion : The prominent symptom of manganese toxicity is the appearance of brown spots surrounded by chlorotic veins.
Reason : Excess of manganese may induce deficiencies of iron, magnesium and calcium.

• A. If both assertion and reason are true and reason is the correct explanation of assertion
• B. If both assertion and reason are true but reason is not the correct explanation of assertion
• C. If assertion is true but reason is false
• D. If both assertion and reason are false

Answer 1

Answer: (B)

Moderate increase in the amount of micronutrients causes toxicity. Toxicity levels for any element also vary for different plants. Many times, excess of an element may inhibit the uptake of another element. For example, the prominent symptom of manganese toxicity is the appearance of brown spots surrounded by chlorotic veins. Manganese competes with iron and magnesium for uptake and with magnesium for binding with enzymes. Manganese also inhibit calcium translocation in shoot apex. Therefore, excess of manganese may induce deficiencies of iron, magnesium and calcium.