3.2 Photosynthesis uses light energy to synthesise organic molecules Flashcards

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1
Q

Where is chlorophyll found?

A

In thylakoid membranes of the chloroplast

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2
Q

What type of feeding is photosynthesis?

A

Autotrophic nutrition

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3
Q

4 photosynthetic pigments

A

Chlorophyll A and B
Carotenes
Xanthophyll

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4
Q

What light is absorbed by chlorophyll?

A

red and blue-violet

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5
Q

What light is absorbed by carotenoids?

A

blue violet

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6
Q

Why do plants appear green?

A

As none of the pigments absorb green light and so it is reflected

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7
Q

Why is it beneficial to have more than 1 pigment type?

A

To absorb a wider range of light waves, allowing more efficient photosynthesis

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8
Q

Why is it beneficial to have more than 1 pigment type?

A

To absorb a wider range of light waves, allowing more efficient photosynthesis

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9
Q

What is shown by the absorption spectra?

A

How much light is absorbed at different wavelengths

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10
Q

What is shown by the action spectra?

A

The rate of photosynthesis at different wavelengths

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11
Q

What are the main functions of the light dependent stage?

A
  1. split water molecules by photolysis releasing H+
  2. ATP synthesis supplying energy for carbohydrate synthesis
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12
Q

What photosystems are used in non cyclic photophosphorylation?

A

PS I and PS II

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13
Q

What photosystems are used in cyclic photophosphorylation?

A

PS I

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14
Q

How do electrons move in non cyclic photophosphorylation?

A

rise up energy levels and move down electron transport chin to next photosystem
Do not return to original photosystem

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15
Q

How do electrons move in cyclic photophosphorylation?

A

Electrons rise up energy levels and then return to original photosystem

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16
Q

What shape are chloroplasts?

A

lens

17
Q

What shape are mitochondria?

A

Rod

18
Q

Organelles of chloroplast (3)

A

Grana, stroma, thylakoid

19
Q

Organelles of mitochondria (2)

A

Cristae, inner matrix

20
Q

What is chemiosmotic theory?

A

ATP synthesis takes place by a flow of protons across membranes, down a conc gradient through the enzyme ATP synthetase in stalked particles.

21
Q

How is light energy absorbed by a plant?

A

Though Photosynthetic pigments in photosystems

22
Q

What happens to the absorbed light energy?

A

it is funneled to the reaction centre where it excited electrons

23
Q

What happens to the excited electrons at PS II?

A

They rise up to an electron receiver where they are then passed down the electron transport chain to PS I

24
Q

What happens as the electrons move down the electron transport chain?

A

Protons are actively transported out if the thylakoid membrane creating a proton gradient

25
Q

What happens to the protons after they leave the membrane?

A

They move from an area of high to low concentration passing through a stalked particle to re-enter the membrane, creating energy

26
Q

What uses the energy created by the proton flow?

A

It catalyses the joining of P to ADP forming ATP via ATP synthetase

27
Q

Where do the electrons and protons come from?

A

The photolysis of water to form 2 protons and 2 electrons- oxygen released as a bi-product

28
Q

What cycle occurs in the light independent reaction?

A

Calvin cycle

29
Q

What is the first stage of the calvin cycle?

A

RuBP is fixed with carbon dioxide in a reaction
catalysed by RUBISCO.

30
Q

What is the second stage of the calivn cycle?

A

RuBP is converted into two glycerate 3-phosphate

31
Q

What is the third stage of the calvin cycle?

A

2 ATP are used to convert glycerate-3-phosphate to glycerate diphosphate

32
Q

What is the fourth stage of the Calvin cycle?

A

Reduced NADP is oxidised as GD goes to triose phosphate

33
Q

What is the 5th stage of the Calvin cycle?

A

ATP is released and most TP regenerates to RUBP
Some forms glucose

34
Q

What are the limiting factors of photosynthesis?

A

Temperature
Light intensity
CO2 Concentration

35
Q

How does temperature affect photosynthesis?

A

Enzyme catalysed reaction, therefore has optimum and can denature

36
Q

How does Light Intensity affect photosynthesis?

A

Limited by number of photosystems
high Light intensity bleaches photosystems

37
Q

How does CO2 concentration affect photosynthesis?

A

Increases the rate of CO2 incorporation in the Calvin cycle and is only limited by other factors

38
Q

Where does the light independent reaction occur?

A

Stroma

39
Q

How does Calvins lollipop experiment work?

A
  1. Algae is grown under light
  2. Radioactive carbon is injected
  3. At intervals, photosynthesising algae are
  4. Dropped into hot methanol, stopping any reactions
  5. Algae are separated in two way chromatography