Answer: Micronutrient.
- A Macronutrient
- B Micronutrient
- C Heavy metal
- D Non-essential element
Correct answer: B. Micronutrient
Explanation: Boron is a micronutrient (trace element) essential in small amounts. It is important for pollen germination, cell wall formation, and sugar transport. Deficiency causes death of growing tips.
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.