Photosynthesis and Respiration

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  • Created by: JosephPHS
  • Created on: 06-02-23 11:29
Photosynthesis General Reaction
6CO₂ + 6H₂O + energy (light )--> C₆H₁₂O₆ + 6O₂
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Where does Photosynthesis occur
Chloroplasts

Light dependant - Thylakoid Membrane
Light independent - Stroma
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Light dependent stage - photolysis
H₂O is split into H⁺ ions, e⁻ and Oxygen by light
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Light dependent reaction - photoionisation
Chlorophyll absorbs light which excites e⁻
e⁻ exit chlorophyll
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Light dependent reaction - ETC
e⁻ travel to the ETC (electron transport chain) where they travel down the chain through a series of redox reactions giving off energy
This energy is then used in ATP synthesis or NADP reduction
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Light dependent reaction - photophosphorylation
H⁺ ions from photolysis diffuse through the ATP synthase enzyme in the thylakoid membrane to enter the stroma
Combined with energy from the ETC this allows for ATP synthesis by oxidative phosphorylation of ADP
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Light dependent reaction - generation of reduced NADP
H⁺ ions from photophosphorylation then bond with NADP molecules with energy from the ETC to form reduced NADP or NADPH molecules
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Light dependent reaction - summary
Light splits H₂O into H⁺ ions, e⁻ and Oxygen
e⁻ in chlorophyll excited by light and travel to ETC
e⁻ travel down ETC through redox, releasing energy
H⁺ diffuses through ATP synthase allowing for phosphorylation of ATP (energy from ETC)
H⁺ combines with NA
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Light independent reaction (Calvin Cycle) - Stages
1. Ribulose bisphosphate (RuBP) (5 Carbon) + CO₂ --> (RuBisCo enzyme) 2 Glycerate-3-Phosphate (GP) (3 Carbon)
2. GP + 2 ATP + 2 NADPH --> 2 Triose Phosphate
(TP) + 2(ADP + Pi) + 2 NADP
3. 2TP + ATP --> (ADP + Pi) + RuBP
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Uses of TP and GP
TP may be used in RuBP synthesis or can be used to produce hexose sugar carbohydrates and lipids
GP can be used to produce TP or to produce
, lipids and amino acids
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Production of hexose sugars from TP
5/6 TP molecules are used for RuBP synthesis and 2 TP are produced for every 1 CO₂ added or for every turn (repetition) of the cycle
Therefore for every 3 turns only 1 TP is produced that is used for hexose sugar production
This means there must be 6 turn
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Optimum conditions for photosynthesis - Light
High light intensity of wavelengths around red (chlorophyll a) and blue (carotene and chlorophyll b) on the light spectrum - photosynthetic pigments absorb different wavelengths and chlorophyll REFLECTS green light giving it its green colour
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Optimum conditions for photosynthesis - Temperature
Temperature around 25 is optimum for enzymes and the stomata
Temperature < 10°C - enzymes become inactive
Temperature > 45°C - Enzymes denature and stomata close
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Optimum conditions for photosynthesis - CO₂
CO₂ around 0.4% of atmospheric gases
Generally CO₂ makes up around 0.04% but a higher % gives a higher rate
If % CO₂ > 0.4 the stomata begin to close
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Respiration General Reaction
C₆H₁₂O₆ + 6O₂ --> 6CO₂ + 6H₂O + energy
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Stages of Respiration
Glycolysis
Link Reaction
Krebs Cycle
Oxidative Phosphorylation
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Stages of Glycolysis
Phosphorylation
Oxidation
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Phosphorylation
Glucose + ATP --> Glucose Phosphate + ADP
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Oxidation
Glucose Phosphate + ATP --> Hexose Bisphosphate + ADP

(Hexose bisphosphate then splits into 2TP)
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Oxidation
TP + 2(ADP + Pi) + NAD --> Pyruvate + 2ATP + NADH

This occurs twice for every molecule of glucose as one molecule of glucose produces 2TP
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Other cards in this set

Card 2

Front

Chloroplasts

Light dependant - Thylakoid Membrane
Light independent - Stroma

Back

Where does Photosynthesis occur

Card 3

Front

H₂O is split into H⁺ ions, e⁻ and Oxygen by light

Back

Preview of the back of card 3

Card 4

Front

Chlorophyll absorbs light which excites e⁻
e⁻ exit chlorophyll

Back

Preview of the back of card 4

Card 5

Front

e⁻ travel to the ETC (electron transport chain) where they travel down the chain through a series of redox reactions giving off energy
This energy is then used in ATP synthesis or NADP reduction

Back

Preview of the back of card 5
View more cards

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