photosynthesis

Question 1

what are the stages of the light dependent stage?

Answer 1

1. light harvesting
2. photolysis of water
3. photophosphorylation
4. formation of reduced NADH

Question 2

What is photolysis of water?

Answer 2

This is the splitting of water in the presence of light

Question 3

What are the uses of photolysis?

Answer 3

• source of protons used in photophosphorylation
• donates electrons to chlorophyll after it loses them when light strikes
  source of oxygen

Question 4

What is the process of non celiac photophosphorylation?

Answer 4

1. light energy sexcites electrons inside a chlorophyll molecule in photosystem 2
2. the electrons escape the mollie and are caught by an electron carrier protein containing an iron ion (FE3+)
3. iron ion becomes reduced after combining with an electron (Fe2+)
4. iron ion donates electron to next electron carrier
5. this continues along a chain of electrons in the thylakoid membrane releasing some energy along the way which is used to pump protons
   6.electrons are collected by a chlorophyll. molecule in photosystem 1
6. feredoxin accepts electrons in ps1 and passes them to NADP in the storm
7. a protein gradient forms in they thylakoid spaces so protons diffuses out of the thylakoids via channel proteins joined to ATP synthase enzymes which cause ATP and phosphate to join and form ATP
8. protons then reach final electron acceptor NADP which is reduced

Question 5

What is the process of cyclic photophosphorylation ?

Answer 5

1.light strikes ps2 and excites a pair of electrons in chlorophyll. molecule
2. electrons escape and pass along a chain
3. ATP generates

Question 6

what is not produced in cyclic?

Answer 6

• o2
• Reduced NADP
• protons

Question 7

Where does the light independent stage take place?

Answer 7

In the storm of chloroplasts

Question 8

What is the first stage of the calvin cycle called and what happens in it?

Answer 8

Carbon dioxide fixation
- Co2 combines with RUBP (catalysed by RuBisco). RUBP accepts the carboxyl group and this forms an unstable gc which turns into 2 3C of GP

Question 9

What is the second stage of the calvin cycle called and what happens in it?

Answer 9

Reduction of GP
- ATP donates a phosphate group to GP and turns into ADP
- Reduced NAD donates hydrogen ions to GP which forms TP

Question 10

What is the third stage of the calvin cycle called and what happens in it?

Answer 10

Regeneration of RUBP
- ATP donates a phosphate group to TP to convert in into RUBP which turns ATP into ADP

Question 11

How many times does the calvin cycle need to occur to produce glucose?

Answer 11

6

Question 12

What are some uses of TP?

Answer 12

• sucrose
• starch
• synthesis of amino acid

Question 13

How does light intensity affect the calvin cycle?

Answer 13

1. GP cannot be reduced to R
   TP
2. GP accumulates and TP falls
3. RUBP cannot regenerated

Question 14

How does Co2 concentration affect the calvin cycle?

Answer 14

1. RUBP cannot be carboxylated so it accumulates
2. GP isn’t made
3. TP cant be made

Question 15

How does temperature affect the calvin cycle?

Answer 15

• at temps above 45 degrees the enzymes involved will be denatured which reduces conc of GP and TP and eventually RUBP
• From 25 - 30 degrees the rat of photosynthesis increases as temperature increases.
• at temperature above 30 degrees oxygen competes with carbon dioxide for RuBisCOs active site.

Question 16

What is the stroma?

Answer 16

A fluid filled matrix of chloroplasts where the light independent reaction takes place

Question 17

What are thylakoids?

Answer 17

flattened membrane bound sacks found in chloroplasts and are the site of the light dependent reaction.