Govt. Exams
Entrance Exams
While soil pH affects nutrient availability, it does not directly affect the photosynthetic process itself. Chlorophyll, CO2, and light wavelength directly influence photosynthesis.
Complex I (NADH dehydrogenase) pumps 4 protons, Complex III pumps 4, Complex IV pumps 2, making Complex I the most significant proton pump.
Transpiration is highly dependent on atmospheric humidity. Lower humidity increases transpiration rate due to greater water vapor gradient.
In plants, anaerobic conditions lead to fermentation producing ethanol and CO2. Aerobic respiration yields ~30-32 ATP; Krebs cycle produces limited ATP directly; Glycolysis is cytoplasmic.
The light compensation point for C3 plants typically occurs at 50-100 μmol/m²/s where photosynthesis equals respiration rate.
The correct electron flow is: PSII (P680) → Plastoquinone → Cytochrome b6f complex → Plastocyanin → PSI (P700) → NADP+ reductase.
During drought, water loss causes cells to lose turgor pressure. ABA accumulation further reduces guard cell turgor by opening K+ efflux channels, closing stomata.
Carotenoids are accessory pigments that absorb light and protect against photoinhibition but do NOT participate directly in CO2 fixation.
CAM plants open stomata at night to fix CO2 as malic acid, stored in vacuoles. During the day, stomata close to reduce water loss while malic acid is decarboxylated for the Calvin cycle.
Photoinhibition occurs when light intensity exceeds the photosynthetic capacity, causing photodamage to PSII reaction center and photodissociation of D1 protein.
