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
What do modern action spectra use
They use electronic data logging instead of bacterial movements
26
How can you show there are several different pigments in plants
Paper chromatography
27
What does chromatography help us work out?
The Rf value | compare it to the original Rf value
28
How can you calculate the Rf value
Distance traveled by a solute (photosynthetic pigment) ------------------------------------------------------------------------------ Distance traveled by the solvent
29
What are the photosystem 1 and photosystem 2
Photosynthetic pigments that carry out the absorption of light in two distinct chlorophyll complexes
30
Where are the following found: PSI PSII
Lamellae | grana
31
Which of the two stages of photosynthesis only takes place at night
Light-independent reactions
32
Where does the light-dependent stage take place
On the thylakoid membrane of the chloroplast
33
What are the two main functions of light-dependent reactions
To split water in a photochemical reaction, providing H+ ions to reduce carbon dioxide and produce carbohydrates The other is to produce ATP
34
What is light | What is the smallest unit of light
A form of electromagnetic radiation | The smallest unit of light is a photon
35
Explain what happens during the light-dependent reaction
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
How do light-dependent reactions lead to the formation of ATP
Either by cyclic or non-cyclic phosphorylation
37
In non-cyclic phosphorylation what else along with ATP is formed
NADPH
38
What does cyclic phosphorylation involve
Only photosystem I and drives the production of ATP
39
Explain the process of cyclic phosphorylation
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
What happens during the Non-cyclic phosphorylation
Water molecules are split, providing hydrogen ions to reduce NADP.
41
Explain the process of Non-cyclic phosphorylation
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
What is the electron acceptor in Non-cyclic phosphorylation
NADP
43
What is the NADP and ATP produced during no cyclic photophosphorylation used for
As a source of reducing power and energy respectively in the light-independent reactions of photosynthesis to make glucose
44
How do chlorophyll molecules reform oxygen
4OH- - 4e- (lost to chlorophyll) ------> O2 +2H20
45
How are carbohydrates formed
The light-dependent stage of photosynthesis uses the reducing power and ATP produced
46
What is the Calvin cycle
A series of small steps result in the reduction of carbon dioxide from the air to bring about the synthesis of carbohydrates
47
Explain what happens in the Calvin cycle
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
When does the Calvin cycle take place
In both the light and dark
49
When does the Calvin cycle stop
In the dark when the products of the light reaction run out, leaving no reduced NADP or ATP available in the chloroplast
50
What is GALP
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
What is the GALP produced in the Calvin cycle used for
To produce glucose in the process called gluconeogenesis
52
What are some of the GALP taken into the glycolysis pathway converted into What can it be used for
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
What are the 3 limiting factors of photosynthesis
Light Carbon dioxide Temperature
54
How does light affect photosynthesis
The amount of light available affects the amount of chlorophyll which is excited therefore the amount
55
How does carbon dioxide affect photosynthesis
If there is not enough carbon dioxide available, the reactions cannot proceed at the maximum rate
56
What is the biggest limiting factor in photosynthesis
Carbon dioxide
57
How does temperature affect photosynthesis
If there is not enough temperature available, the reactions cannot proceed at the maximum rate