Interrelationship between the process of photosynthesis and respiration
Respiration reactants= Photosynthesis products
Respiration products= Photosynthesis reactants
Respiration- releases energy
Photosynthesis- traps energy
Chloroplast Structure- Network of membranes
Network of membranes provide a large surface area to maximise the absorption of light in first stage in photosynthesis
Chloroplast Structure- Outer membrane
Separates intermembrane space from cytosol. Part of the chloroplast envelope.
Chloroplast Structure- Lamellae
A sheet like membrane found within a chloroplast. They are membranous channels which join grana together.
Chloroplast Structure- Grana
Thylakoidsstacked together.
Chloroplast Structure- Thylakoids
Provides a large surface area for the photosynthetic pigments. Site of light-dependent reactions. Contains chlorophyll that is used to absorb light.
Chloroplast Structure- Stroma
Contains enzymes, light independent reactions take place here. Site of chemical reactions resulting in the formation of complex organic molecules.
Chloroplast Structure- DNA
Contains the genetic info that allows the chloroplast ribosomes to produce proteins needed for photosynthesis.
What is the site of the light dependent reactions?
thylakoids
What is the site of the light independent reactions?
stroma
Chlorophyll a
The primary pigment. Absorbs red and blue light reflecting green light. (pigment in plants that absorbs light energy)
Name other types of pigments
Chlorophyll b, xanthophylls, carotenoids (accessory pigments). They all absorb different wavelengths of light that chlorophyll a does not absorb.
What is a light harvesting complex?
chlorophyll b, xanthophyll's and carotenoids are embedded in the thylakoid membrane of chloroplast to form a light-harvesting system with other proteins.
Absorbs different wavelengths of light energy and transfer this energy to the reaction centre.
What is in the middle of the reaction center and what is its function.
Chlorophyll a
Reactions of photosynthesis take place here.
Photosystem
cluster of pigments and proteins found in thylakoids. Light harvesting system and reaction center collectively known as a photosystem.
1) The light absorbed excites electrons at the reaction centres of the photosystem
Non-cyclic photophosphorylation- stage 2 after electrons are excited
2) they are released from from reaction centre of PSII and are passed to an electron transport chain to produce ATP by chemiosmosis.
How are electrons lost from the reaction centre during non-cyclic photophosphorylation replaced in PSII
Using electrons from the photolysis of water
Non-cyclic photophosphorylation- stage 3 after electrons are excited in PSI
3) electrons are released from the reaction centre to another electron transport chain to produce more ATP by chemiosmosis
How are electrons lost from the reaction centre during non-cyclic photophosphorylation replaced in PSI
Using electrons from PSII
Non-cyclic photophosphorylation- stage 4 as electrons leave the electron transport chain
4) electrons leaving are accepted by coenzyme NADP to form NADPH
Photolysis
Using light, water is split to form oxygen, hydrogen ions, and electrons
What happens to H+ ions formed from photolysis
Protons are released into the lumen of the thylakoids, increasing proton concentration across the membrane. They come back down the gradient to form more ATP. Once back they combine with NADP and electron from PSI to form NADPH
Cyclic-photophosphorylation
electrons leaving PSI can be returned back to PSI instead of forming NADPH. No need for electrons from PSII when this happens
Differences between cyclic photophosphorylation and non-cyclic photophosphorylation
Non-cyclic photophosphorylation: ATP and NADPH produced. Both PSI AND PSII involved.
Cyclic photophosphorylation: ATP ONLY produced. PSI ONLY involved.
Light-independent stage
Second stage of photosynthesis. Involves using ATP, reduced NADP (products of light dependent reactions) and carbon dioxide (raw material) to make organic molecules.
Light-independent stage- Calvin cycle: how does carbon dioxide enter (raw material)
Carbon dioxide enters the intercellular spaces within the spongy mesophyll of leaves by diffusion from the atmosphere through the stomata
light is needed as an energy source. As light intensity increases, ATP and NADPH are produced at a higher rate.
Limiting factor- carbon dioxide concentration
needed as a source of carbon, increasing rate of carbon dioxide increases rate of carbon fixation in the Calvin cycle and therefore the rate of TP production