Answer: Interveinal chlorosis in young leaves.
- A Purple coloration appearing across the stems and petioles
- B Interveinal chlorosis in young leaves
- C Sudden wilting of the entire shoot system
- D Unusually thick, dark green leaves overall
Correct answer: B. Interveinal chlorosis in young leaves
Explanation: Iron deficiency causes interveinal chlorosis (yellowing between veins while veins remain green) first in young leaves because iron is immobile in plants. Iron is needed for chlorophyll synthesis and electron transport.
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.