Review for Exam 3 - Photosynthesis

Question 1

where does Calvin Cycle (“synthesis” part of photosynthesis) take place?

Answer 1

in the stroma

Question 2

where do the light reactions (“photo’ part of photosynthesis) take place?

Answer 2

thylakoids

Question 3

chemiosmosis

Answer 3

generation of ATP by the movement of hydrogen ions across a membrane during cellular respiration or photosynthesis.

Question 4

PEP carboxylase

Answer 4

• enzyme used in C4 plants and CAM
• has a much higher affinity for CO2 than rubisco does
• no affinity for O2

Question 5

cyclic photophosphorylation

Answer 5

happens in primitive plants
PS I - 700 nm (absorbs light)
output - only ATP
inputs - light, ADP, Pi

Question 6

non-cyclic photophosphorylation

Answer 6

inputs:
- light
- water
- ADP
- Pi
- NADP

Outputs:
O2
ATP
NADPH

Question 7

Calvin Cycle (aka C3 plants)

Answer 7

KEY REGULATORY STEP: RuBisco (enzyme) catalyzes CO2 w/5-C compound ribulose bisphospate (RuBP) to make 2 - 3-C compounds

inputs:
- CO2
- ATP
- NADPH
outputs:
- CH2O (glucose)
- ADP
- Pi
- NADP+

Question 8

RuBisCo

Answer 8

• probably most abundant protein on earth
• can “fix” (has an affinity for) CO2 and O2
  REGULATED BY
  1. [CO2} and [O2] in the cell
  2. [Mg2+]
  3. pH
  4. NADPH levels - activity is stimulated by greater levels of this generated during light reactions

Question 9

xylem

Answer 9

water and minerals

Question 10

phloem

Answer 10

sugar

Question 11

how is light energy converted to chemical energy in light reactions of photosynthesis?

Answer 11

light energy is used to excite electrons to a higher energy state.
electrons are them used in ETC to make ATP or NADPH

Question 12

C4 plants

Answer 12

enzyme: phosphoenolpyruvate carboxylase
(PEP carboxylase)
- limited to mesophyll cells

Question 13

CAM plants

Answer 13

• carry out C3 reactions during day
• carry out C4 reactions at night
• both done in the same cell: mesophyll cell