Photosynthesis (Chapter 11) Flashcards
What are adaptations of leaves?
- Lots of stomata
- Thin
- Transparent cuticle
- Air spaces in lower mesophyll space
- Large SA
- Xylem for input of water
What are in chloroplasts?
Thylakoid, Grana, Inner and Outer Membrane, Intergranal Lamellae, Stroma
Describe a thylakoid
Disc like structure where the 1st stage of photsyntheis takes place. Has a large SA.
Describe the inner and outer membrane
Large SA and permeable
Describe the Grana
Stacks of thylakoids
Describe the intergranal lamellae
Tubular structures between grana
Describe the Stroma
A fluid-filled matrix where the 2nd stage of photosynthesis takes place. Contains enzymes for photosynthesis.
Describe the stages of the light-dependent stage
1) Light absorbed by chlorophyll, exciting electrons
2) Electrons leave chlorophyll and pass along electron protein carriers in thylakoid membrane.
3) Photoionisation of chlorophyll. Some of the energy released by electrons is used to make ATP catalysed by ATP synthase embedded in membranes.
4) Light also splits water (photolysis). Water provides protons for the production
Where does the light-dependent stage take place?
Thylakoid
Where does the light-independent stage take place?
The stroma
Describe the stages of the light-independent stage
1) CO2 enters the stroma and combines with RuBP (5 carbon) using the enzyme rubisco.
2) Makes 2x GP (3 carbon)
3) GP is reduced to make 2x TP (3 carbon). ATP and NADPH from light-dependent stage used - ATP supplies energy for rxn/NADPH provides H.
4) Some TP used to make glucose and other used to regenerate RuBP. Uses ATP.
What does the light-dependent stage need and make?
Needs: NADP, ADP Pi, and water
Makes: NADPH, ATP, and oxygen
What does the light-independent stage need and use?
Needs: ATP
Makes: Glucose (regenerates RuBP)
What is used to track the stages of the light-dependent rxn and why?
Radioactive carbon as it can become incorporated into new compounds.
What is used to measure the rate of photosynthesis?
Photosynthometer - measure O2 released or CO2 taken up.
What can be the limiting factor for photosynthesis?
- Light
- Temperature
- CO2 concentration
How does increasing temperature affect the rate of photosynthesis/ respiration?
More kinetic energy so more enzyme-substrate complexes form.
What are the similarities between photosynthesis and respiration?
- Use and release ATP
- Use of chain electron carriers
- Processes controlled by enzymes
- Use oxidation/reduction reactions
- Involves cycles of reactions
What is chromatography used for?
Method to separate pigments
Describe how to carry out a chromatography experiment with leaves
1) Level of solvent below origin/line.
2) Remove/stop before solvent reaches the top.
3) Leaves have pigments of different colours which causes different wavelengths of light to be absorbed.
Why is the origin always drawn in pencil?
Ink and leaf pigments would mix and with pencil the origin line is still visible.
How do you draw a graph of a limiting factor?
The diagonal line shows the limiting factor and when the line flattens out then another factor is limiting.
Why do leaves have different coloured pigments?
Allows different/more wavelengths of light to be absorbed for photosynthesis.
Why is a large SA of a leaf advantageous?
Absorbs maximum amount of sunlight for photosynthesis.
