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Topic Notes · Easy summaries with diagrams
Chapter 9 — Chapter 9 — Plant Physiology
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📘Easy summary
Nutrition: processes in which food is prepared or obtained and converted into body substances. Besides photosynthesis, plants need mineral nutrients — chemical elements absorbed from soil essential for growth.
⭐Key points
- Macronutrients (large quantities): C, H, O, P, K, N, S, Ca, Mg.
- Micronutrients (small quantities): Fe, Mo, B, Cu, Mn, Zn, Cl, Ni.
- K regulates opening/closing of stomata; N in proteins, chlorophyll, enzymes; Mg in chlorophyll.
- Nitrogen absorbed as nitrates; deficiency → slow growth, yellow leaves (chlorosis).
- Magnesium absorbed as Mg²⁺; deficiency → chlorophyll breakdown, chlorosis, leaf drop.
- Deficient N/Mg moved from older to younger leaves, so older leaves yellow first.
🔬Diagram
🌿Real-life example
Farmers add urea (nitrogen) so wheat leaves stay green and plants grow fast.
💡Exam tip
- Potassium = large amount (MCQ 1); Mg for chlorophyll (MCQ 2).
✅Quick check
1. Chlorosis means:
2. Which is a micronutrient?
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