Photosynthesis Flashcards

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1
Q

Where does the light dependent reaction occur?

A

Thylakoid membrane

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2
Q

Where does the light independent reaction occur?

A

The stroma

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3
Q

Draw and describe the structure of a chloroplast [7]

A

Diagram must contain
1. Inner membrane
2. Outer membrane
3. Stroma
4. Thylakoid
5. Thylakoid membrane
6. Granum
7. Intergranum lamellae

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4
Q

What is the photolysis equation?

A

H2O -> 2H+ + 2e- + 1/2O2

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5
Q

What is photolysis?

A

The splitting of water due to light

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6
Q

What are the hydrogen ions from photolysis used for?

A

Reducing coenzyme NADP to reduced NADP

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7
Q

What are the electrons from photolysis used for?

A

Used in the photo systems in the light dependent stage of photosynthesis

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8
Q

What happens when sunlight hits the first photosystem in the light dependent reaction?

A

In photosystem 2 the electrons are excited and move into the electron transfer carriers

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9
Q

What happens as electrons move across the electron transfer carriers in the light dependent stage of photosynthesis?

A

Each transfer releases energy allowing H+ ions to be pumped into membrane to make ATP

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10
Q

What is cyclic phosphorylation?

A

When electrons leaving photosystem 1 return to the photosystem after passing through the electron transfer carrier chain

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11
Q

What is the other name for the light independent stage of photosynthesis?

A

The Calvin cycle

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12
Q

In stage 1 of the Calvin cycle what reaction occurs using carbon dioxide?
What is the catalyst for this reaction?

A

CO2 + RuBP = 6 carbon unstable molecule
The enzyme RuBisCo catalyses this reaction

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13
Q

What inhibits the RuBisCo enzyme used in the Calvin cycle?

A

OXYGEN

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14
Q

What does the unstable 6 carbon molecule, made from the reaction between CO2 AND RuBisCo, break up into?

A

2 x 3 carbon molecules called GP

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15
Q

What does GP get converted into during the Colvin cycle, and using what molecules?

A

GP get converted into TP
It does this using the products of the light dependent reaction in photosynthesis - ATP & reduced NADP

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16
Q

What two things does TP go on to make in the Calvin cycle

A
  1. Lipids, glucose, amino acids and carbohydrates
  2. Regenerated RuBP (used in stage 1 of the Calvin cycle)
    To produce 1 glucose molecule, the Calvin cycle needs to happen 6 times - this resulting in 10 spare TP molecules, which can be shuffled to make 6 RuBP molecules
17
Q

What are the 4 limiting factors of photosynthesis?

A
  1. Light intensity
  2. CO2 concentration
  3. Temperature
  4. Water stress
18
Q

How does light intensity impact rate of photosynthesis?

A

Low levels of light intensity impact rate of photosynthesis as there will be fewer of the products (Reduced NADP & ATP) of the light dependent reaction, which will slow down the light independent reaction

19
Q

How does CO2 concentration impact rate of photosynthesis?

A

If there is less CO2 the reaction between carbon dioxide and RuBP will occur at a slower rate, slowing down the Calvin cycle

20
Q

How does temperature impact the rate of photosynthesis?

A

In the light independent reaction the enzyme RuBisCo may be affected by temperature change impacting the rate of reaction between CO2 and RuBP

21
Q

How does water stress affect rate of photosynthesis?

A

In an attempt to lose less water plants will close their stomata, however this prevents carbon dioxide form entering stopping the light independent reaction occurring

22
Q

What is the impact of low light intensity on the Calvin cycle?

A

The amount of GP will increase as there is no ATP or reduced NADP to convert it to TP and then RuBP, meaning concentration of TP and RuBP will decrease

23
Q

What is the impact of low carbon dioxide concentration on the Calvin cycle?

A

Both GP and TP will decrease as there is no carbon dioxide to react with RuBP to make these products, however RuBP concentration will increase

24
Q

What is a light harvesting system?

A

A light harvesting system is a combination of accessory pigments and their proteins

25
Q

What is the reaction centre of a photosystem?

A

The primary pigment (chlorophyll a) and its proteins
The reaction centre is surrounded by accessory pigments

26
Q

Why is it important the the primary pigment and different accessory pigments absorb different wavelengths of light?

A

So that the maximum amount of light energy can be absorbed

27
Q

What does a photosystem consist of?

A

The light harvesting system and the reaction centre