Chap 9-10 - Respiration & Photosynthesis

Question 1

Location of chlorophyll

Answer 1

Thylakoid membranes

Question 2

Electron carriers in respiration vs photosynthesis

Answer 2

NAD+ in cellular respiration
NADP+ in photosynthesis
(P for photosynthesis!)

Question 3

3 pigments in chloroplasts
(+ colours)

Answer 3

• Chlorophyll a (red/purple)
• Chlorophyll b (blue & orange)
• Carotenoids (turquoise to purple)

Question 4

Photosystem

Answer 4

Light-capturing unit, consisting of the Reaction-Centre Complex and surrounding Light-Harvesting Complex.

Classified into I and II.

Question 5

Reaction-centre complex

Answer 5

Contains a pair of chlorophyll a that passes energy to an electron carrier when excited.

Question 6

P680 chlorophyll a vs P700 chlorophyll a

Answer 6

P680 - in Photosystem II.
P700 - in Photosystem I.

Question 7

Carotenoid functions

Answer 7

• Accessory pigments that absorb blue and a bit of red.
• Absorb/dissipate excess light that may be harmful.

Question 8

Linear electron flow path in photosynthesis

Answer 8

1. Photon excites reaction-centre of Photosystem II.
2. Energy passed to electron receptor.
3. H2O is split to resupply the electron lost.
4. ETC - ATP is made.
5. Electron passed to Photosystem I.
6. Passed to Fd and then NADPH.

Goes to calvin cycle.

Question 9

Cyclic electron flow inputs/outputs

Answer 9

Photosystem II not needed.
- Makes ATP
- Doesn’t use H2O
- Not involved in calvin cycle - no glucose made.

Question 10

Cyclic electron flow path

Answer 10

1. Photosystem I excited.
2. Electron passed to Fd.
3. Fd passes electron into the middle of the ETC.
4. At the end of ETC, electron returns to Photosystem I.

Question 11

Calvin cycle phases

Answer 11

1. Fixation
2. Reduction
3. Restoration

Question 12

Fixation (Calvin cycle)

Answer 12

• CO2 attached onto RuBP by enzyme Rubisco.
• Product splits into 3-carbon molecules.

Question 13

Reduction (Calvin cycle)

Answer 13

• Each molecule needs a phosphate (from ATP) and an NADPH to become G3P.
• 6ATP + 6NADPH needed for one net G3P

Question 14

Restoration (Calvin cycle)

Answer 14

• 3ATP used to form 3RuBP from the five remaining G3P.

Question 15

Calvin cycle inputs to make one net G3P

Answer 15

9ATP
6NADPH
3CO2

Question 16

Photorespiration

Answer 16

Wasteful reaction that occurs if O2 concentration is too high in the leaf; uses ATP to convert a waste produce to CO2.

Question 17

C4 photosynthesis

Answer 17

CO2 is fixed into a 4-carbon molecule that can’t bind O2.
CO2 released in bundle-sheath cells - mesophyll cells cannot carry out Calvin cycle.

More efficient at capturing CO2 but with ATP cost.

Question 18

CAM pathway

Answer 18

CO2 is fixed at night into organic acids; acids are stored in vacoules, and then CO2 released in the day for Calvin cycle.

Question 19

How many G3P per glucose

Answer 19

Two!
And 4 to make sucrose.