Unit 4: Photosynthesis

Question 1

In what organisms does photosynthesis take place?

Answer 1

Plants, algae, some protists, some bacteria

Question 2

Where does photosynthesis occur?

Answer 2

Chloroplasts

Question 3

What two types of reactions occur in photosynthesis?

Answer 3

1. Light-dependant reactions

2. Carbon reactions

Question 4

What is the sight of ETS?

Answer 4

Thylakoids

Question 5

True or false: The chloroplast stroma is the equivalent of the mitochondrial matrix

Answer 5

True

Question 6

What is chlorophyll?

Answer 6

• a pigment
• in thylakoid membranes
• absorbs light energy

Question 7

What does chlorophyll absorb?

Answer 7

Blue and red

Question 8

What does chlorophyll reflect?

Answer 8

Green

Question 9

What is another type of pigment?

Answer 9

Carotenoids

Question 10

What do accessory pigments do?

Answer 10

• Absorb visible light at wavelengths Chl cannot

- Transfer light energy to Chl

Question 11

What are the functions of Chl in its excited state?

Answer 11

• Transfer energy to another pigment
• Fluorescence
• Heat
• Used in chemical reactions

Question 12

What are the products of liner photophosphorylation?

Answer 12

Oxygen, NADPH, proton gradient

Question 13

What are the characteristics of photosystem II?

Answer 13

1. Light is absorbed by antenna pigments
2. Energy transferred to reaction center P680
3. Excited electron transferred to electron acceptor
4. oxygen evolving complex pulls electrons out of H2O and gives them to P680

Question 14

What is the role of plastoquinone?

Answer 14

PQ picks up protons from stroma to form PQH2

Question 15

What doe PQH2 do?

Answer 15

Move through the membrane; transfers electrons from PSII to cytochrome b6-f complex?

Question 16

What are the characteristics of cytochrome b6-f?

Answer 16

• Removes protons from PQH2 and transfers them to lumen

- Transfers electrons from PQH2 to plastocyanin

Question 17

What are the characteristics of plastocyanin?

Answer 17

• It moves across the membrane

- Transfers electrons from cyt. b6-f to photosystem I.

Question 18

What are the characteristics of photosystem I?

Answer 18

1. antenna pigments absorb light energy
2. energy transferred to reaction center P700
3. P700 transfers energy to electrons
4. electron transfer continues to ferredoxin

Question 19

What is the role of ferredoxin?

Answer 19

Transfer electrons to ferredoxin NADP+ reductase (FNR)

Question 20

What is the role of ferredoxin NADP+ reductase?

Answer 20

• Transfer electrons from Fd to NADP+
• Adds H+ from stroma to NADP+
• Forms NADPH

Question 21

True or false: There is a high proton concentration in the stroma.

Answer 21

False. It is low. The high concentration of protons is in the lumen.

Question 22

What is produced with chemiosmosis?

Answer 22

ATP using ADP+Pi

Question 23

In what direction do protons move during chemiosmosis?

Answer 23

From the lumen to the stroma.

Question 24

What is the purpose of cyclic photophosphorylation?

Answer 24

• Used to produce extra ATP

- Increase H+ gradient

Question 25

What are not products of cyclic photophosphorylation?

Answer 25

- No NADPH is produced | - No oxygen is produced

Question 26

True or false: Photosystem II is not used in cyclic photophosphorylation.

Answer 26

True.

Question 27

What are the basic steps of cyclic photophosphorylation?

Answer 27

- Electron transfer near the end of PSI - Back to PQ which reacts with b6-f complex PQH-->b6f-->PC-->PSI - energy from electron transfer used to power proton pump

Question 28

What are other names (though some are inaccurate) form the Cavin Cycle?

Answer 28

- light-independent reactions | - dark reactions (inaccurate)

Question 29

Where does the Calvin Cycle occur?

Answer 29

In the stroma of chloroplast

Question 30

What does the Calvin do?

Answer 30

- Fixes CO2 (converts it to organic form) | - Uses ATP and NADPH made by light reactions

Question 31

What are the 3 stages of the Calvin Cycle?

Answer 31

- Carboxylation (CO2 added to 5-carbon RuBP) - Reduction (forms glyceraldehyde-3-phosphate (G3P)) - Regeneration of RuBP

Question 32

What enzyme is used in carboxylation?

Answer 32

Rubisco

Question 33

What is produced during carboxylation?

Answer 33

2 molecules of 3-phsophoglycerate (3PG)

Question 34

What is produced during reduction?

Answer 34

1 molecule of 3PG produces 1 molecule of 1,3-biphosphoglycerate Then 1 molecule of 1,3-biphosphoglycerate produces of glyceraldehyde-3-phosphate (G3P) NOTE: a total of 6 G3P are produced since stage 1 is repeated 3 times

Question 35

What happens in regeneration?

Answer 35

1. 5 of the 6 G3P produced are used to regenerate RuBP | 2. 1 of the 6 G3P produced is used to make carbohydrates

Question 36

True or false: If the G3P is exported to the cytosol then sucrose is made.

Answer 36

True.

Question 37

True or false: If the G3P remains in the chloroplast, then its converted to glucose and stored as starch.

Answer 37

True.