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Biology 5.2 > Photosynthesis > Flashcards

Photosynthesis Flashcards

1
Q

What are autotrophic organisms

A

They make complex organic compounds from the simple compound in their environment

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2
Q

What is photosynthesis

A

The process by which living organisms, particularly plants, capture the energy of the sun using chlorophyll and use it to convert carbon dioxide and water into simple sugars

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3
Q

What is glucose used for in the plant?

A

Energy source by the cell of the plant, and as the building blocks of other important molecules such as proteins.

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4
Q

What are heterotrophic organisms

A

Obtain complex molecules by feeding on other living organisms or their dead remains

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5
Q

What is the ultimate energy source for almost all organisms

A

The sun

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6
Q

What is the equation for photosynthesis

A

Carbon dioxide + water —> glucose + oxygen

6CO2 + 6H20 —> C6H12O6 + 6O2

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7
Q

What is the light energy used for in photosynthesis

What is the waste product for photosynthesis

A

It is used to split the strong H-O bond in the water molecules
Oxygen

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8
Q

What are the main 2 steps in photosynthesis

A

light dependent reaction and light independent reactions

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9
Q

What is chlorophyll

A

Relatively large organelles found in the cells of the green part of plants

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10
Q

What is chloroplast surrounded by

A

An outer and an inner membrane with a space between two, known as the chloroplast envelope

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11
Q

What is inside the chloroplast

A

There is a system of membranes that are arranged in stacks called grana

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12
Q

What is a single granum made from

A

They are made up of stacks of membrane disks known as thylakoids

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13
Q

What is chlorophyll

A

A green pigment found in the chloroplast

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14
Q

Where is the chlorophyll found

A

In the thylakoid

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15
Q

What is the grana membrane covered in and how do we know

A

In particles that are involved in ATP synthesis

seen in electron micrographs

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16
Q

How are the grana joined together

A

by lamellae

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17
Q

What do the lamellae act as in plants

A

As a skeleton within the chloroplast so they get maximum light and function properly

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18
Q

What is a stroma and what does it contain

A

Surrounds membrane stacks by a matrix

It contains all the enzymes needed to complete photosynthesis

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19
Q

What are the 4 main chlorophyll pigments

A 
chlorophyll a (blue-green)
chlorophyll b (yellow-green)
carotenoids (orange carotene and yellow xanthophyll)
Phaeophytin (grey pigment)
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20
Q

which chlorophyll pigment is the most abundant

A

chlorophyll a

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21
Q

Where is chlorophyll a always found

A

In all photosynthesizing plants

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22
Q

What does the absorption spectrum describe

A

The range of the amount of light of different wavelengths that a photosynthetic pigment absorbs
represented as a graph

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23
Q

How is the absorption spectra of different photosynthetic pigments absorbed

A

Measuring their absorption of light of different wavelengths

24
Q

What is an action spectrum

A

A way of demonstrating the rate of photosynthesis against the wavelength of light

25
Q

What do modern action spectra use

A

They use electronic data logging instead of bacterial movements

26
Q

How can you show there are several different pigments in plants

A

Paper chromatography

27
Q

What does chromatography help us work out?

A

The Rf value

compare it to the original Rf value

28
Q

How can you calculate the Rf value

A 
          Distance traveled by the solvent
29
Q

What are the photosystem 1 and photosystem 2

A

Photosynthetic pigments that carry out the absorption of light in two distinct chlorophyll complexes

30
Q

Where are the following found:
PSI
PSII

A

Lamellae

grana

31
Q

Which of the two stages of photosynthesis only takes place at night

A

Light-independent reactions

32
Q

Where does the light-dependent stage take place

A

On the thylakoid membrane of the chloroplast

33
Q

What are the two main functions of light-dependent reactions

A

To split water in a photochemical reaction, providing H+ ions to reduce carbon dioxide and produce carbohydrates
The other is to produce ATP

34
Q

What is light

What is the smallest unit of light

A

A form of electromagnetic radiation

The smallest unit of light is a photon

35
Q

Explain what happens during the light-dependent reaction

A

A photon of light hits a chlorophyll molecule
The energy is transferred to the electrons of the molecule
The electrons are excited and are raised to a higher energy level
It will leave the chlorophyll molecule completely
The electron can be accepted by an electron acceptor and results in the synthesis of ATP.

36
Q

How do light-dependent reactions lead to the formation of ATP

A

Either by cyclic or non-cyclic phosphorylation

37
Q

In non-cyclic phosphorylation what else along with ATP is formed

A

NADPH

38
Q

What does cyclic phosphorylation involve

A

Only photosystem I and drives the production of ATP

39
Q

Explain the process of cyclic phosphorylation

A

Light hits a chlorophyll molecule in PSI
A light excited electron leaves the molecule
It’s taken up by an electron acceptor and passed directly along an electron transport chain to produce
ATP
When an electron returns to the chlorophyll molecule in PSI, it can be excited in the same way

40
Q

What happens during the Non-cyclic phosphorylation

A

Water molecules are split, providing hydrogen ions to reduce NADP.

41
Q

Explain the process of Non-cyclic phosphorylation

A

Under light conditions, photons are constantly hitting chlorophyll molecules in both PSI and PSII
Excited electrons move to a higher energy level for them to be lost and picked up by an electron acceptor.
An excited electron from PSII is picked up by electron acceptor and passed along an electron transport chain to PSI
PSI receives an electron to replace one that was lost to the light-dependent reactions
The chlorophyll of PSII is unstable and lacking an electron
The electron comes from photolysis (splitting of water)
Once PSII has the electron it is restored to the original state, ready for the light to hit it and excite the electron

42
Q

What is the electron acceptor in Non-cyclic phosphorylation

A

NADP

43
Q

What is the NADP and ATP produced during no cyclic photophosphorylation used for

A

As a source of reducing power and energy respectively in the light-independent reactions of photosynthesis to make glucose

44
Q

How do chlorophyll molecules reform oxygen

A

4OH- - 4e- (lost to chlorophyll) ——> O2 +2H20

45
Q

How are carbohydrates formed

A

The light-dependent stage of photosynthesis uses the reducing power and ATP produced

46
Q

What is the Calvin cycle

A

A series of small steps result in the reduction of carbon dioxide from the air to bring about the synthesis of carbohydrates

47
Q

Explain what happens in the Calvin cycle

A

Carbon dioxide from the air combines with 5-carbon compound RuBP in the chloroplast
Carbon dioxide is said to be fixed (carbon fixation)
Carbon dioxide + RuBP = 6C
The 6C is immediately broken down into two glycerate-3-phosphate
glycerate 3 phosphate is then reduced to form glyceraldehyde 3-phosphate (GALP)
The hydrogen for this reduction comes from the NADP
The GALP replaces the RuBP in the first reaction however some of it forms glucose

48
Q

When does the Calvin cycle take place

A

In both the light and dark

49
Q

When does the Calvin cycle stop

A

In the dark when the products of the light reaction run out, leaving no reduced NADP or ATP available in the chloroplast

50
Q

What is GALP

A

The primary end-product of the process of photosynthesis and it is the key molecule for the synthesis of everything else needed in the plant

51
Q

What is the GALP produced in the Calvin cycle used for

A

To produce glucose in the process called gluconeogenesis

52
Q

What are some of the GALP taken into the glycolysis pathway converted into
What can it be used for

A

Acetyl CoA
Which in turn can be used to synthesize fatty acids needed for the production of phospholipids for membranes, and lipids needed for storage and other functions within the plants

53
Q

What are the 3 limiting factors of photosynthesis

A

Light
Carbon dioxide
Temperature

54
Q

How does light affect photosynthesis

A

The amount of light available affects the amount of chlorophyll which is excited therefore the amount

55
Q

How does carbon dioxide affect photosynthesis

A

If there is not enough carbon dioxide available, the reactions cannot proceed at the maximum rate

56
Q

What is the biggest limiting factor in photosynthesis

A

Carbon dioxide

57
Q

How does temperature affect photosynthesis

A

If there is not enough temperature available, the reactions cannot proceed at the maximum rate

Biology 5.2 (1 decks)

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