Module 7

1. Phosphorus is essential for energy transfer (ATP, NADPH).
2. Potassium regulates osmotic balance and stomatal movement.
3. Sulfur is a component of amino acids cysteine and methionine.
4. Calcium is important for cell wall and membrane stability.
5. Magnesium is the central atom in chlorophyll.
6. Iron is needed for chlorophyll synthesis and electron transport.
7. Zinc is required for auxin synthesis.
8. Manganese activates water-splitting enzyme in photosynthesis.
9. Boron is important for pollen germination and sugar transport.
10. Molybdenum is essential for nitrogen fixation.
11. Deficiency of nitrogen causes chlorosis in older leaves.
12. Deficiency of iron causes chlorosis in younger leaves.
13. Deficiency of boron causes death of terminal buds.
14. Hydroponics is used to study nutrient requirements.
15. Liebig’s Law of Minimum: growth is limited by the scarcest nutrient.
16. Blackman’s Law of Limiting Factors: rate is limited by the slowest process.
17. Carbon fixation in C3 plants via Rubisco, in C4 via PEP carboxylase.
18. Bundle sheath cells are large and chloroplast-rich in C4 plants.
19. C4 pathway reduces photorespiration losses.
20. Photosynthetically Active Radiation (PAR) = 400–700 nm.
21. Optimum temperature for C3 plants ≈ 20–25°C; for C4 ≈ 30–40°C.
22. Light saturation point is higher for C4 than C3 plants.
23. Net assimilation rate (NAR) indicates leaf efficiency in photosynthesis.
24. Chlorosis is yellowing due to loss of chlorophyll.
25. Etiolation is excessive elongation in absence of light.
26. Senescence is the last stage of development before death.
27. Seed dormancy ensures survival under adverse conditions.
28. Vivipary is premature germination of seeds on mother plant.
29. Dry matter partitioning affects crop yield potential.
30. Canopy architecture influences light interception and productivity.
31. Assimilate partitioning determines distribution of photosynthates among organs.
32. Sink strength is the ability of an organ to attract assimilates.
33. Source capacity depends on photosynthetic rate and leaf area duration.
34. Photoassimilates are mainly transported as sucrose in most crops.
35. Phloem transport occurs by pressure-flow hypothesis (Münch, 1930).
36. Xylem transport follows the cohesion-tension theory (Dixon & Joly, 1894).
37. Transpiration pull is the main driving force for water movement in xylem.
38. Root pressure helps in xylem ascent during low transpiration.
39. Water-use efficiency (WUE) = Biomass / Water used.
40. C4 plants have higher WUE than C3 plants.
41. Stomatal resistance increases under drought and ABA influence.
42. Hydraulic conductivity decreases under soil compaction.
43. Osmotic adjustment helps plants tolerate drought by solute accumulation.
44. Compatible solutes like proline, glycine betaine maintain turgor under stress.
45. ABA is known as stress hormone in plants.
46. Ethylene promotes senescence and fruit ripening.
47. Cytokinins counteract ABA and delay senescence.
48. Leaf senescence is genetically programmed (programmed cell death).
49. Autotrophy is the ability to synthesize organic food from inorganic sources.
50. Respiratory substrate is any organic compound oxidized in respiration.
51. Dark respiration occurs both in light and dark.
52. Photorespiration occurs only in light and in presence of oxygen.