Photosynthesis limiting factors
- Created by: Steff06
- Created on: 25-03-16 09:15
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- Photoynthesis - Limiting factors
- Key factors include: LIGHT intensity + quality, CARBON DIOXIDE concentration, TEMPERATURE, WATER, NUTRIENTS.
- Law of limiting factors:
- When a process is affected by a number of factors, the factor in the SHORTEST SUPPLY at a given time determines the overall RATE of the process.
- Light quality and intensity:
- At LOW light intensities, as light INTENSITY INCREASES, RATE of photosynthesis INCREASES and is a LIMTIING factor.
- At HIGH LIGHT intensities, rate of phototsynthesis PLATEAUS and light is no longer a limiting factor as it doesn't affect the rate.
- CO2:
- CO2 is a SUBSTRATE for photosynthesis and so increasing CO2 conc INCREASES RATE of photosynthesis.
- At some point the rate of photosynthesis will PLATEAU.
- Temperature:
- INCREASING temperature INCREASES RATE of photosynthesis up to an OPTIMUM. At too HIGH a temperature, enzymes may DENATURE and rate will PLATEAU.
- LIGHT has 3 main effects: OPENS STOMATA so CO2 can enter leaves. Trapped by CHLOROPHYLL where it EXCITES electrons. SPLITS WATER molecules to produce PROTONS.
- Light INDEPENEDENT stage is ENZYME CONTROLLED whilst the light DEPENDENT stage is NOT.
- When light is NOT limiting it is TEMPERATURE DEPENDENT and more likely to be enzyme controlled DEPENDENT
- Increase in TEMP and decreasing rate shows ENZYME controlled.
- When limited by light, it is temperature INSENSITIVE and NOT enzyme controlled.
- Increase in TEMP and decreasing rate shows ENZYME controlled.
- When light is NOT limiting it is TEMPERATURE DEPENDENT and more likely to be enzyme controlled DEPENDENT
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