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A2 BIOLOGY > 3.2 photosynthesis > Flashcards

3.2 photosynthesis Flashcards

1
Q

what is the photosynthesis

A

the process by which carbohydrates are synthesised from carbon dioxide and water using light energy

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2
Q

what is the main site of photosynthesis in plants

A

palisade mesophyll cells/ tissue

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3
Q

what part of the lead has the most chloroplast

A

top part of the lead in the palisade cell

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4
Q

structure of a leaf

A
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5
Q

where does photosynthesis take place

A

in chloroplasts

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6
Q

what do chloroplasts contain

A

photosynthetic pigments which absorb light energy at particular wavelengths of light

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7
Q

how are leaves adapted for photosynthesis

A

-spongy mesophyll, air spaces for gas exchange
-large SA (flat and thin)
- waxy cuticle (reduce water loss)
- thin, upper layer is transparent so light can penetrate through the leaf (short diffusion distance)

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8
Q

how are chloroplasts adapted for photosynthesis

A

stacked thylakpids (increase SA)
move around to optimise light absorption
chloroplasts have many grana, large SA

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9
Q

what is an energy transducer

A

something that changes energy from light into chemical energy

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10
Q

why do plants look green

A

plants absorb light from all electromagnetic spectrum except for the colour green, it is reflected

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11
Q

how can photosynthetic pigments be seoarated

A

using chromatography

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12
Q

what is a photosynthetic pigment

A

a photosynthetic pigment is a chemical substance that is present in chloroplasts to absorb the light energy necessary for photosynthesis
green plants usually have 2 different closely-related groups of photosynthetic pigments

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13
Q

what are the 2 different groups of photosynthetic pigments

A

chlorophyll and carotenoids

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14
Q

different chlorophylls
where are they present

A

chlorophyll a
chlorophyll b
they’re all green, found in green plants

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15
Q

carotenoids

A

carotene (orange and in all plants)
xanthophyll (yellow and in most plants)

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16
Q

what is the absorption spectrum

A

a graph to show the absorbance of different wavelengths of light by a pigment

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17
Q

what is the action spectrum

A

a graph to show the rate of photosynthesis at different wavelengths of light

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18
Q

explain Thomas Englemann’s experiment

A

he devised an experiment to determine which wavelength of light were used most for photosynthesis. he placed the algae spirogyra in a suspension of motile aerobic bacteria. he used a prism to refract white light into its constituent rainbow colours, the most oxygen will be produced at the wavelengths of light used most for photosynthesis

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19
Q

what did Englemann conclude

A

the blue and red regions of the spectrum caused the most photosynthetic activity

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20
Q

where are photsysytems found

A

embedded in the thylakoid membrane

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21
Q

explain how light harvesting works

A

energy from a broard range of wavelengths absorbed by an ‘antenna’ complex of an accessory pigment is ‘funneled down’ to a reaction centre

22
Q

example of accessory pigments

A

chlorophyll B/ carteroids

23
Q

where is the reaction centre found

A

at the base of the photosysten, it contains a pair of chlorophyll A molecules

24
Q

what does the antenna complex contain

A

many different light absorbing pigments

25
Q

puprose of the photosystem

A

to trap as much light energy as possible

26
Q

how many photosystems are there

A

2

27
Q

at what wavelength does chlrophyll A absorb light in photosystem 1 and 2

A
  1. 700nm
  2. 680 nm
28
Q

what is the light dependent stage

A

photophosphorylation

29
Q

what happens in the light dependent stage

A

electrons lost from the reaction centre pass along a chain of electron acceptors which power a hydrogen pump that carries a H+ ion from the stroma to the thylakoid lumen

30
Q

what is photophosphorylation

A

the addition of a phosphate group to ADP to form ATP using light energy

31
Q

2 types of phosphorylation

A

cyclic/non-cyclic

32
Q

what photosystem does cyclic phosphorylation involve

A

just photosystem 1

33
Q

explain cyclic phosphorylation

A

a photon of light hits photosystem 1, 2 electrons become excited, they pass to an electron acceptor, this is donated to the ETC which generates a proton gradient for chemiosmosis. the electrom is passed back to PS1.

34
Q

what is the purpose of the ETC generating energy
cyclic phosphorylation

A

energy is needed so H+ ions go from stroma to the thylakoid lumen.

35
Q

non-cyclic photophosphorylation

A

an alternative pathway, both photosystems
high energy electrons from PS1

36
Q
A
37
Q

what does photolysis provide and what is it

A

provides an electron for PSII
molecules of water absorb light energy and split to form electrons protons and oxygen

38
Q

what do the electrons from photolysis do

A

passed to PSII to replace those lost during non-cyclic photophosphorylation

39
Q

what do the protons from photolysis do

A

used to reduce NADP each NADP molecule picks up 2 protons and 2 electrons to become reduced

40
Q

what are the products of the light dependent stage

A

ATP and reduced NADP
both are needed in the calvin cucle

41
Q

what is the light independent stage

A

the calvin cycle, it fixes carbon dioxide into glucose using ATP (from photophosphorylation) and reduced NADP

42
Q

where does the calvin cycle happen

A

stroma

43
Q

what controls the calvin cycle

A

enzymes

44
Q

3 stages of the calvin cycle

A

fixation
reduction
making glucose and regeneration of rubulose bisphosphate

45
Q

explain the first stage of the calvin cycle

A

carbon dioxide is taken up by 5C ribulose bisphosphate to form an unstable 6c molecule (catalysed by rubisco)
this 6c molecule then dissociates into 2 glycerate 3 phosphate molecules

46
Q

explain the second stage of the calvin cycle

A

Glycerate 3 phosphate is reduced (gains 2H atoms) into triose phosphate using ATP
NADP reduced goes to NADP (gives up H atoms)

47
Q

explain the third stage of the calvin cycle

A

5/6 of triose phosphate is used t make ribulose phosphate
1/6 of triose phosphate is used to mkae glucose (can be converted into fructose or sucrose and starch)
ribulose phosphate is converted to RuBp using ATP (ADP+Pi)

48
Q

how many turns of the calvin cycle to make glucose

A

6

49
Q

mineral requirements for plants
nitrates

A

are needed for amino acid and protein production as well as nucleic acid production to make DNA for new cells. it’s eady to see how stunted growth it a classic deficiency symptom in plants lacking a nitrogen source

50
Q

mineral requirements for plants
magnesium

A

(found in chlorophyll) is an integral part of the molecule and is essential for its production. if plants are growing in an area with limited magnesium supply then they suffer a deficiency disease known as chlorosis

A2 BIOLOGY (8 decks)

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