1 / 15

Limiting factors

Limiting factors. Limiting factors. Biochemical rxns such as photosynthesis involve a series of reactions,hence,its rate is limited by the slowest rxn in the series

francesca-gould
Download Presentation

Limiting factors

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Limiting factors

  2. Limiting factors • Biochemical rxns such as photosynthesis involve a series of reactions,hence,its rate is limited by the slowest rxn in the series • Eg. the light independent rxn requires ATP and reduced NADP produced in the light dependent rxn. At low light intensity the rate at which ATP and reduced NADP are produced is too slow to allow the light independent rxn to occur

  3. Limiting factor • “The principle of limiting factors states that when a chemical process, such as photosynthesis, is affected by more than one factor then it is the factor that is nearest to minimum value that would directly affect the rate of the process if its quantity changes.”

  4. factors that affect the rate of photosynthesis • Light • CO2 concentration • Temperature • Availability of water • Chlorophyll concentration • Inhibitors • Pollution • Inorganic ions

  5. LIGHT • needed for photosynthesis to occur in the light dependent reactions • At low light intensities if there is an increase then there will also be one in the rate of photosynthesis, however this only occurs if the other factors are in sufficient supply otherwise they themselves become rate-limiting • Light is generally in a good supply except for shady leaves which adapt by increasing the concentration of chlorophyll.

  6. Light intensity

  7. Light intensity • Rate of photosynthesis increases as light intensity increases-light is a limiting factor since if the plant receives more light it will photosynthesize faster • At a certain point if light intensity is increased the rate of photosynthesis does not increase-light saturation • Hence, light is no longer a limiting factor

  8. Light intensity/co2 conc.

  9. CO2 CONCENTRATION • needed for the light independent reactions • atmosphere consists of about 0.03%-0.04% of CO2, therefore it is very limiting • if its concentration is increased provided that all others are kept at a maximum value the rate of photosynthesis is increased • This is important in increasing the yield of crops grown in green houses by increasing the concentration of CO2 to which plants are exposed to by about 0.1%

  10. Co2 concentration

  11. Co2 concentration • needed in the light independent rxn • Usually a major limiting factor • 0.03-0.04% in the atmosphere • 0.1% needed for sustained high rate

  12. Co2 and light intensity

  13. TEMPERATURE • most of the reactions in both stages of photosynthesis require the support from enzymes which are temperature sensitive and thus operate at an optimum temperature • Enzymes kinetic energy increases with increasing temp • At optimum temp rate of rxn is max. • Beyond opt temp rate decreases as enzymes become denatured (lose their shape and catalytic properties)

  14. Effect of temperature

  15. Use of limiting factors to increase crop productivity • Refer to text pg. 12

More Related