Back to AI Flashcard MakerBiology /A-level Biology - 3.3.2 Photosynthesis Part 3
The Light-independent Reaction Describe stage 1
CO2 enters through stomata & diffuses into stroma CO2 combines with RuBP Catalysed by enzyme rubisco Gives an unstable 6C which breaks down quickly into 2x GP (3C)
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Term
Definition
The Light-independent Reaction Describe stage 1
CO2 enters through stomata & diffuses into stroma CO2 combines with RuBP Catalysed by enzyme rubisco Gives an unstable 6C which breaks down quickly in...
The Light-independent Reaction Describe stage 2
(Hydrolysis of) ATP provides energy to change GP → TP (3C) Reduced NADP provides H+ ions so it can reduce GP → TP Reduced NADP is recycled to NADP TP ...
The Light-independent Reaction Describe stage 3
5/6 of TP produced used to regenerate RuBP NOT make hexose sugars Regenerating RuBP uses rest of ATP produced by light-dependent reaction
What are TP and GP molecules used to make?
Carbohydrates, lipids and amino acids
Describe how hexose sugars made (carbohydrates)
Made by joining 2 TP molecules together
Draw the Calvin cycle (include the no. of carbons)
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| Term | Definition |
|---|---|
The Light-independent Reaction Describe stage 1 | CO2 enters through stomata & diffuses into stroma CO2 combines with RuBP Catalysed by enzyme rubisco Gives an unstable 6C which breaks down quickly into 2x GP (3C) |
The Light-independent Reaction Describe stage 2 | (Hydrolysis of) ATP provides energy to change GP → TP (3C) Reduced NADP provides H+ ions so it can reduce GP → TP Reduced NADP is recycled to NADP TP is then converted into useful organic compounds (e.g. glucose) & some continues in Calvin cycle to regenerate RuBP |
The Light-independent Reaction Describe stage 3 | 5/6 of TP produced used to regenerate RuBP NOT make hexose sugars Regenerating RuBP uses rest of ATP produced by light-dependent reaction |
What are TP and GP molecules used to make? | Carbohydrates, lipids and amino acids |
Describe how hexose sugars made (carbohydrates) | Made by joining 2 TP molecules together |
Draw the Calvin cycle (include the no. of carbons) | |
Describe how larger carbohydrates (e.g. sucrose, starch, cellulose) are made | Made by joining hexose sugars together in different ways |
Describe how lipids are made | Made using glycerol, which is synthesised from TP, and fatty acids, which are synthesised from GP |
Describe how some amino acids are made | Some amino acids are made from GP |
Explain why the Calvin cycle needs to turn 6 times to make 1 hexose sugar | 3 turns of cycle = 6x TP ∵ 2x TP are made for every 1 CO2 molecule used 5/6 TP used to regenerates RuBP Means for 3 turns = only 1 TP is produced that's used to make hexose sugar But hexose sugar has 6 C ∴ 2x TP needed to form 1 hexose sugar Means cycled must turn 6 times to produce 2x TP that can be used to make 1 hexose sugar |
6 turns of cycle need ___ ATP and ___ reduced NADP from light-dependent reaction | 6 turns of cycle need 18 ATP and 12 reduced NADP from light-dependent reaction |
What are coenzymes? | Molecules that aids function of an enzyme |
How do coenzymes work? | Work by transferring a chemical group from 1 molecule to another |
Name a coenzyme in photosynthesis | NADP |
Explain how NADP is a coenzyme | Transfers hydrogen from 1 molecule to another Means it can reduce (give hydrogen to) or oxidise (take hydrogen from) a molecule |
Name 3 limiting factors of photosynthesis | Light intensity Temperature Carbon dioxide concentration |
Describe how light intensity affects the rate of photosynthesis | Higher intensity of light = more energy for light-dependent reaction Rate of photosynthesis ↑ |
Describe and explain what happen to the rate of photosynthesis at too high temperatures | High temps = enzymes denature Photosyntheis stops High temps = stomata close to avoid losing too much water Causes photosynthesis to slow down ∵ less CO2 enters leaf when stomata are closed |
Describe how could you test the effect of light intensity on the rate of photosynthesis | Source of white light placed at a specific distance from pondweed Pondweed placed (stem side up - cut stem at slant) in sodium hydrogen carbonate solution to photosynthesis for 5 mins Number of bubbles produced are counted Variables (e.g. temperature, time) should be controlled Experiment repeated thrice with light source at same distance = mean no. bubbles calculated Whole experiment is repeated with light source at different distances from pondweed Convert distances from lamp to light intensity Process your data and use suitable statistical test to investigate correlation between light intensity and rate of photosynthesis |
Give the formula for converting distances from lamp to light intensity | 1/d² d = distance from plant to lamp |