Answer: Yellow leaves due to lack of chlorophyll.
- A Dark green leaves with thickened cuticle
- B Yellow leaves due to lack of chlorophyll
- C Purple/red leaves from anthocyanin buildup
- D Brown, dry leaves from tissue necrosis
Correct answer: B. Yellow leaves due to lack of chlorophyll
Explanation: Chlorosis is yellowing of leaves due to reduced chlorophyll production. It is caused by deficiency of nitrogen, magnesium, iron, sulfur, or manganese. It indicates mineral deficiency.
Atmospheric N₂ is fixed into ammonia by nitrogen-fixing bacteria (protected from oxygen by leghaemoglobin in root nodules), converted to nitrate via nitrification for plant uptake, and eventually returned to the atmosphere as N₂ via denitrification, completing the cycle.
Concept context
Essential mineral elements, their roles and deficiency symptoms. Nitrogen fixation and soil nutrition.