Energy Transfers Flashcards
Give the symbol and chemical equations for photosynthesis and respiration
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What are the three stages of photosynthesis
Capturing light energy
Light- dependent reaction
Light- independent reaction
How are leaves adapted to maximise absorption of light and gas exchange
Large surface area- absorb as much light as possible
Leaves arranged to minimise overlapping
Thin- short diffusion distance
Transparent cuticle and epidermis - let light through to photosynthetic cells
Long, narrow upper mesophyll- packed with chloroplasts
Stacks of thylakoids - large sa
Lost of stomata - opens and close depending on light intensity
Air spaces in the lower mesophyll - rapid diffusion
What do chloroplasts contain in order to aid photosynthesis
Photosynthetic pigments
Chlorophyll a, chlorophyll b, carotene
- found in thylakoid membrane
Attached to proteins
Protein and pigment-> photosystem
Absorb different wavelengths of light
Where does the light dependent reaction take place
Thylakoid membrane
What is light energy needed for in LDR
Making atp- photophosphorylation
Making reduced nadp form nad
Splitting after into protons, electrons and oxygen- photolysis
What is photolysis
Splitting of water
Using light energy
H2O -> 2H+ + 1/2O2 + 2e-
Describe photoionisation
Light energy is absorbed by PSII
Light excites eelctorns within the PSII and causes them to move to a higher energy level
How are electrons lost form the PSII replaced
Photolysis
How is a proton gradient formed in the LDR
Electrons move form high to low energy along the electron transport chain
The energy lost by electrons is used to pump hydrogen ions form the stroma into the thylakoid membrane
which generates a proton gradient across the thylakoid membrane
What does chemiosmosis do
Protons flow down their concentration gradient through ATP synthase
Th energy movement of protons is used to phosphorylate ADP to ATP
Describe the light dependent reaction
• Light energy excites electrons / raises electrons to a higher energy level / removes electrons (from chlorophyll); (1 mark]
• The electrons move along electron carriers / the electron transfer chain releasing energy OR movement of H+/protons across chloroplast membrane releases energy; [1 mark]
• The energy is used to join ADP with Pi to form ATP / for phosphorylation of ADP to ATP; [1 mark]
• Photolysis of water (H2O) produces electrons, oxygen and protons; (1 mark]
• NADP is reduced by electrons / electrons and H+ / hydrogen OR NADP is reduced to NADPH by the addition of electrons/hydrogen; [1 mark]
