Quantum yield represents the photosynthetic efficiency, defined as the number of CO2 molecules fixed per photon absorbed (typically 8-10 photons per CO2).
Guttation occurs through specialized pores called hydathodes located at the leaf margins, allowing liquid water to be exuded when root pressure exceeds transpiration.
Light reactions do not require CO2. CO2 is used in the dark reaction (Calvin cycle). Light reactions produce ATP, NADPH, and O2.
At compensation point, the rate of CO2 fixation in photosynthesis equals the rate of CO2 release in respiration, resulting in net zero gas exchange.
ABA accumulates in guard cells during water stress and causes stomatal closure by reducing turgor pressure in guard cells.
In C4 plants, CO2 first combines with PEP (3-carbon molecule) to form oxaloacetate (4-carbon), which is why it's called C4 photosynthesis.
Soil pH has minimal direct effect on transpiration rate. Primary factors affecting transpiration are light, humidity, temperature, and wind velocity.
Chlorophyll a is the primary pigment that directly participates in the photochemical reactions of both PSI and PSII, while other pigments act as accessory pigments.
At high temperatures, Rubisco and other enzymes denature reducing their activity. Additionally, stomata close to prevent excessive water loss, reducing CO2 availability and thus net photosynthesis.
Plasmodesmata are cytoplasmic bridges allowing symplastic movement of water, minerals, and even macromolecules like proteins and RNA between adjacent cells.