Ethylene is the major hormone controlling senescence (aging) in plants, promoting leaf yellowing, fruit ripening, and abscission.

The Z-scheme illustrates electron flow from PSII through the cytochrome b6f complex to PSI, showing how electrons are elevated twice to reach NADP+ reduction.

Nitrosomonas is a chemosynthetic bacterium that oxidizes ammonia to nitrite, obtaining energy without requiring light (unlike photosynthetic organisms).

CAM plants have the lowest transpiration coefficient because they open stomata only at night, minimizing water loss while fixing CO2 efficiently.

While plant cells lack true centrosomes with centrioles, plasmodesmata serve similar intercellular communication functions. However, most plant cells lack a distinct MTOC (microtubule-organizing center).

The saturation point is the CO2 concentration beyond which photosynthesis rate does not increase further, limited by other factors like temperature or light.

Plasmolysis is the shrinkage of protoplasm away from the cell wall when placed in hypertonic solution. It's reversible if not prolonged.

Using v² = u² - 2gh, where final velocity v = 0, u = 40 m/s, g = 10 m/s². We get h = 1600/20 = 80 m

Newton is a derived unit (kg⋅m⋅s⁻²). Ampere, Kelvin, and Mole are SI base units

Using v² = u² + 2as, where v = 0, u = 20 m/s, a = -5 m/s². We get s = 400/10 = 40 m