(a) Photosynthesis: The process by which green plants; manufacture/ synthesize their food/organic compounds; from carbon dioxide and water; in the presence of sunlight/solar energy; giving off oxygen as a byproduct. OR
(b) (i) External Factors: Light intensity/sunlight; carbon dioxide concentration; temperature; pollution; water
(ii) Internal factors: Hormones; chlorophyll/presence of ehiorophyll/ebloroplast; enzymes; number/state of stomata
(c)(i) Major products of light-dependent stage of photosynthesis: - ATP (Adenosine triophosphate)/energy, -H+ (Hydrogen ion), - OH- (Hydroxyl ion), - NADPH2 (reduced nicotinamide adenine dinucleotide phosphate), - 0² (oxygen gas).
(ii) Importance of the products: -ATP to generate energy for the dark stage reaction, - 2H+ NADP→ NADPH2, - 0H- (Hydroxyl ion)→ H2O, O2 gas, NADPH2 - to generate hydrogen ions/to reduce carbon dioxide /C02 to form carbohydrate in the dark stage; - 02 - given off into the atmosphere for animals/other organisms to use for respiration.
(d) (i) Why green plants are absent at the lower depth of some lakes: Light intensity decreases with depth in water bodies; so at certain depths in water, there is no light for photosynthesis to occur.
(ii) Importance of decomposers to flowering plants: Decomposers (fungi/bacteria) break down dead organic matter; and release the nutrients in them; 002 in the soil/water/environment; which is absorbed by plants for growth.