Photosynthesis
- Created by: elen roberts
- Created on: 11-12-13 12:36
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- Photosynthesis and Limiting Factors
- Chloroplasts
- Have a thylakoid membrane folded into vesicles (thylakoids)
- Stacked to form Grana
- ContainsATP synthesis particals
- Store products of photosynthesis as starch grains & Lipid droplets
- Have a thylakoid membrane folded into vesicles (thylakoids)
- Chlorophyll
- Contain chlorophyll a, b & other accessory pigments, absorb light at different wavelengths
- Low absorption - cant be used.
- Measure rate of photosynthesis using wavelengths gives action spectrum
- arranged in photosystems
- In the Thylakoid membranes
- Contain chlorophyll a, b & other accessory pigments, absorb light at different wavelengths
- Light dependant stage
- Thylakoid membrane
- 1. Light energy splits water. H+ reduces NADP. e- excite electrons in PII, they go to electron carrier.
- 2. Electrons down e.c.s where e- are lost to convert ADP+P -> ATP
- 3. Light energy excites e- at PI, up to e.c. Some are recycled for more ATP
- 4. Excited electrons down e.c.s to form NADP. Combine with H+ to create Reduced NADP
- 3. Light energy excites e- at PI, up to e.c. Some are recycled for more ATP
- 2. Electrons down e.c.s where e- are lost to convert ADP+P -> ATP
- Light independent stage
- Stroma
- 1. CO2 binds to 5carbon RUBP to form 2 molecules of GP using rubisco
- 2. GP is an acid, reduced & activated using ATP & R.NADP to form TP
- 3. most TP regenerates to RUBP using ATP. The rest leaves the cycle to form glucose
- 2. GP is an acid, reduced & activated using ATP & R.NADP to form TP
- Factors affecting rate of photosynthesis
- Measured by O2 released or uptake of CO2
- Affected by respiration. Compensation point - photosynthesis & respiration are equal
- Temperature
- Most effects photosynthesis. above compensation point, plant loses mass - R greater than P
- CO2 concentration
- Substrate for rubisco. R not affected, P speeds up. Compensation level is low
- Light intensity
- Source of energy for P1. R not affected. P speeds up. Compensation point is low.
- Time of day
- Affects R & P by light & temp. Night - R exceeds P. Day - P exceeds R. 2 compensation points each 24hrs. Overall, P is greater than R so plant gains mass.
- Limiting factors
- Only 1 factor controlling rate, the furthest from optimum.
- Uses for farmers and commercial growers
- Can change conditions and consentrations to prevent/reduce limiting factors.
- Measured by O2 released or uptake of CO2
- Chloroplasts
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