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Flashcards in Photosynthesis Deck (19):
0

CO2 concentration on the calvin cycle

- needed to make GP
- so if conc is low
- less GP = less TP
- RUBP can build up, but also less TP to replace it but replacing is prioritised over glucose production
- some RUBP levels fall under prolonged lack of CO2

1

Light on the calvin cycle

- requires products from light dependent stage to get GP to TP
- if dark GP builds up and NO TP produced
- used when light levels increase

2

Limiting factor

- a factor preventing a reaction or process from going any faster
- increase factor = increase rate

3

Factors affecting photosynthesis

- UNTIL ANOTHER LIMITING FACTOR
- light intensity - increased light intensity = increases rate of photosynthesis
- CO2 conc - increased CO2 conc = rate of photosynthesis
- temperature -increased temp = increased collisions = rate of photosynthesis (in light independent)
- BUT too high enzymes denature rubisco catalyses O2 = photorespiration

4

The light independent stage

- in the stroma
- produces organic molecules
- RUBP (ribulose bisphosphate) -> CO2 + rubisco -> intermediate-> GP (2 x glycerate-3-phosphate) -> amino acids/fatty acids OR + ATP-ADP NADPred-NADP -> TP (2 x triose phosphate)-> glucose/sucrose -> ATP-ADP -> ribulose bisphosphate

5

Non- cyclic photophosphorylation

- PS1and PS11
- produces ATP, NADPred, O2
- light that hits PS11 activates enzyme that causes photolysis
- H+ ions form NADPred with e from PS1
- e from PS11 replaces the one in PS1
-produces ATP as the electrons travel down the etc

6

Cyclic photophosphorylation

-PS1
- produces ATP
- light energy excites an electron that leaves the chlorophyll molecule
- the electron travels along the electron transport chain losing energy thats used to produce ATP
- e returns to PS1

7

Photophosphorylation

- phosphorylation using light
- adding a phosphate group to ADP to form ATP using light energy
- as the electron passes along ETC loses energy that can be used for phosphorylation

8

Photosystems

- contain proteins and pigment molecules
- across the thylakoid membrane
- light energy captured by accessory pigments and funnelled to reaction centre
- PS1 - P700
- PS11 - P680

9

Light dependent reactions

- in the thylakoid membrane
- involves cyclic and non- cyclic photophosphorylation
- Input - light, H2O, NADP
-output- ATP, oxygen, NADPred

10

Accessory pigments

- ie carotenoids and xanthophyll
- they absorb wavelengths of light other pigments cant
- funnelled the light energy to the reaction centre
- probably protect chlorophyll from intense light

11

Photosynthetic pigment

- A substance that absorbs sone wavelengths of light
-the light reflected creates the colour of the pigment
-ie chlorophyll carotenoids and xanthophyll

12

Thylakoid

- the fluid filled sacs inside lamellae
- can be arranged in stacs to form grana
- sight of light dependent reactions

13

Chloroplasts

- in palisade mesophyll tissues and spongy mesophyll tissue
- contain circular DNA & ribosomes
- surrounded by 2 membranes = envelope
- lamellae sheets form a membrane around thylakoids
- contain starch grains
- site of photosynthesis

14

Stroma

- background material inside the chloroplast
- site of the light independent reactions

15

Grana

- stacks of thylakoid discs

16

Lamellae

- the membrane that encloses thylakoid in chloroplasts

17

Autotrophs

- an organism that makes its own complex organic molecules from an inorganic source
- ie plants photosynthesise light energy

18

Heterotrophsp

- an organism that requires organic nutrients to supply it with a source of carbon