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Biology A Level > Photosynthesis > Flashcards

Flashcards in Photosynthesis Deck (20):
1

what is an autotroph

an autotroph is an organism that uses an energy source to make complex carbohydrate

2

what are the two main groups of autotrophs

-Chemoautotrophs (bacteria) make carbohydrates using chemical energy

Photoautotrophs-(plants + algae) use light energy to make carbohydrates

3

what is the equation for photosynthesis

Carbon dioxide + water --> Glucose + Oxygen
(on arrow- sunlight, chlorophyll)

4

What are the two stages of photosynthesis

Light dependent stage
Light independent stage

5

where does photosynthesis take place

chloroplast

6

what are the photosynthetic pigments found in chloroplasts

-Chlorophylls e.g chlorophyll a and chlorophyll b
-carotenoids e.g carotene and xanthophyll

7

where in the chloroplast does the light dependent reaction happen

thylakoid membrane

8

what is photoionisation

-photons of light excite the electrons in chlorophyl
-continued excitation causes the release of the electrons
-the e- can then be passed down electron transport chain

9

explain the light dependent reaction

-chlorophyl A on photosystem II absorbs photon of light- this excites the electrons to higher energy levels
- electron passed down electron transport chain to plastoquinone B6F to Photosystem I
the electron is reexcited at PS I
-as the electron is passed down the chain, it drops down energy levels. this energy is used to pump H+ from the stroma into the thylakoid lumen
-NADP+ is the final electron acceptor --> NADPH
-the original e- is replaced through the oxidation of water to produce 2O2 + 4H+ + 4e-
-the H+ in the thylakoid lumen diffuse back into the stroma through ATP synthase to produce ATP

10

what wavelength of light does photosystem II absorb

680nm

11

what wavelength of light does photosystem I absorb

700nm

12

what products are taken from the light dependent reaction to the light independent reaction

NADPH
ATP

13

where does the light independent reaction take place

stroma

14

what is another name for the light independent reaction

Calvin cycle

15

explain how the light independent reaction happens

-Carbon dioxide reacts with Ribulose-1,5-biphosphate (RuBP) to form 2 molecules of Glycerate 3 phosphate through
-catalysed by Ru Bis Co
-energy from ATP and NADPH
-some Glycerate 3 phosphate recycled to RuBP- process uses ATP
-some Glycerate 3 phosphate can be converted to useful organic substances

16

what reaction joins CO2 to Ribulose biphosphate

carbon fixation

17

what is an electron transport chain

a series of complexes that transfer electrons between electron donors and electron acceptors through redox reactions

18

in the light dependent reaction what are the 2 forms of photophosphorylation

Cyclic- electron from PS I recycled to PS II
non cyclic- NADPH as final acceptor and Water as donor

19

what factors limit the rate of photosynthesis

light
water
carbon dioxide

20

what happens if there is not enough magnesium

chlorosis
mg is in chlorophyll a- unable to make chlorophyll a