Question

What are the internal factors of photosynthesis??how do they affect photosynthesis?

Answer 1

Dear student,

The various factors that affect rate of photosynthesis are:

• Light

  • Incident light ∝ CO ₂ fixation rate; but at higher light intensities, the rate does not increase further as other factors become limiting
  • Light is rarely a limiting factor (with exception of the shade plants or plants of dense forest) because light saturation occurs at 10% of the full sunlight.
  • Beyond a point, if incident light is increased, then it leads to decrease in photosynthesis due to breakdown of chlorophyll.

• CO₂ Concentration

  • Major limiting factor
  • Usually low in atmosphere (0.03 − 0.04%)
  • Up to 0.05% − increases rate of CO ₂ fixation
  • > 0.05% − damaging effect
  • Though both C3 and C4 show increase in rate of photosynthesis at high light intensity accompanied by high CO₂ concentration,the saturation point for C3 is obtained at higher concentrations as compared to C4 .Therefore, CO₂ concentration is more of a limiting factor for C3 plants.
  • Increased CO₂ concentration is beneficial for greenhouse crops such as tomatoes and bell paper.

• Temperature

  • Dark reactions are more sensitive to an increase in temperature.
  • C4 plants respond more to an increase in temperature as compared to C3 plants.
  • Adaptations according to habitat also effect temperature optima. Tropical plants have higher temperature optima compared to temperate.

• Water

  • Water stress causes stomata to close and hence, less CO₂ is available.
  • Water stress causes the leaves to wilt, thereby reducing their surface area and metabolic activity as well

Regards