Section 5 - Energy Transfer In And Between Organisms

Question 1

What parts of the leaf contain the most chloroplasts?

Answer 1

Mesophyll tissue and guard cells

Question 2

Where in the chloroplasts is chlorophyll (and other photosynthetic pigments) located?

Answer 2

Attached to proteins in the thylakoid membranes, forming photosystems

Question 3

Explain the process required to separate chloroplasts from a leaf

Answer 3

1. Break open tissue/cells and filter
2. In cold, same water potential, pH controlled solution
3. Centrifuge and remove nuclei/cell debris
4. Centrifuge at higher speed. Chloroplasts settle out

Question 4

What are the two processes involved in the light dependent stage of photosynthesis?

Answer 4

Non-cyclic phosphorylation
Cyclic phosphorylation

Question 5

What are coenzymes?
Add 3 examples

Answer 5

Carrier molecules that some enzymes require to function
E.g. FAD, NAD, NADP

Question 6

Where does the light dependent stage of photosynthesis occur?

Answer 6

The thylakoid membrane

Question 7

Describe the process of non-cyclic phosphorylation [LONG]

Answer 7

1. Photons of light absorbed by chlorophyll in PS2
2. This excites electrons, causing them to move to a higher energy level - photoionisation
3. Photosystems linked by proteins called ‘electron carriers’. Together they form the ETC. Electrons leave the chlorophyll and move down ETC to PS1
4. Light energy used to split water (photolysis) - forming protons, electrons and oxygen. The electrons replace those lost from PS2
5. Electrons lose energy as they move down ETC. This energy is used to pump protons into thylakoid space from stroma
6. Protons move down conc. gradient back into stroma via embedded ATP synthase. The energy from this allows ATP to form
7. Repeat steps 1 and 2 in PS1
8. NADP reductase used to transfer electrons from PS1 to NADP, along with a proton from the stroma to form NADPH. Electrons from PS2 replace those lost from PS1