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AQA Biology A2 > Photosynthesis > Flashcards

Flashcards in Photosynthesis Deck (36)
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1
Q

Which ptotosystem appears first in the sequence of the light dependent reactions? [1]

A

Photosystem 2

2
Q

Explain why the word equation of photosynthesis is not accurate of the whole process [1]

A

Implies that is a single step reaction and other products are also made

3
Q

What is required to excite 2 electrons from photosystem 2? [1]

A

Photon of visible light

4
Q

Give the word and symbol equation for photolysis [2]

A

Water –> Electrons + Oxygen + Hydrogen ions

H20 -> 2e- + 1/2O2 +2H+

5
Q

Define the term photolysis [1]

A

The splitting of a molecule of water of water using visible light

6
Q

When NADP is reacted with two electrons and two protons it becomes what? [1]

A

Reduced NADP or NADPH

7
Q

What is the main difference between cyclic and non cyclic photo-phosphorylation? [2]

A

Non cyclic requires an external source of electrons whereas cyclic can keep using the same electrons over and over again

8
Q

Draw out the stages of the light dependent reactions [4]

A

Check diagram in pack

9
Q

State the reaction of chemeosmosis [1]

A

ADP + Pi -> ATP

10
Q

Where does the energy require for chemeosmosis come from [1]

A

Energy given of at the electron transport chain

11
Q

Where within the chloroplast does the light dependent stage take place? [1]

A

Within the thylakoid membrane

12
Q

What is the initial reactant involved in the light independent reactions? [1]

A

RUBP

13
Q

What does RUBP stand for? [1]

A

Ribulose biphosphate

14
Q

What is the function of the rubisco enzyme? [1]

A

To fix CO2 to RUBP

15
Q

Suggest where the CO2 for the fixing comes from? [1]

A

The air

16
Q

What is the enzyme that fixes CO2 to RUBP called? [1]

A

Rubisco

17
Q

After fixing CO2 and RUBP form what? [1]

A

GP

18
Q

Why isn’t GP very useful? [2]

A

Very unstable so breaks apart easily

19
Q

What does GP stand for? [1]

A

Glycerate (III) Phosphate

20
Q

How does GP form TP? [2]

A

H+ donated from NADPH and energy required in the form of ATP

21
Q

What does TP stand for? [1]

A

Triose phosphate

22
Q

What happens to the majority of TP? [1]

A

It is phosphorylated and regenerates RUBP

23
Q

What happens to the minority or TP? [1]

A

Used within the plant to form amino acids, sugars and lipids.

24
Q

The light independent reactions are more commonly known as the what? [1]

A

Calvin - Benson cycle

25
Q

Expalin what is meant by CO2 fixation? [2]

A

The conversion of a gaseous molecule into an organic compound

26
Q

At what point in the Calvin cycle is there a reduction reaction taking place? [1]

A

GP is reduced when it gains e- from NAPDH in order to form TP

27
Q

How many times must the cycle go around for one molecule of glucose to be produced? [1]

A

6

28
Q

Explain why the light independent reactions could not carry on for a very long time without any light? [1]

A

Because you would run out of ATP and NADPH both of which are produced in the LDR so light needed in order for this to occur

29
Q

Draw out the Calvin cycle [4]

A

See diagram in pack

30
Q

List the three factors that limit the rate of photosynthesis [3]

A

Light intensity
Carbon dioxide concentration
Temperature

31
Q

Suggest why temperature in a limiting factor? [2]

A

Because the greater the temperature the more Ke therefore the rate of enzyme controlled reactions is increased (CO2 fixation in the presence of rubisco

32
Q

Suggest why CO2 concentration is a limiting factor? [2]

A

Because CO2 is required to be fixed to RUBP. The more CO2 the more GP can be produced so the Calvin cycle proceeds at a greater rate.

33
Q

A horizontal line on a rate / factor x suggests what? [1]

A

Another factor - not x - is limmiting

34
Q

What abbreviation can be used for concentration? [1]

A

[]

35
Q

The light compensation point is what? [2]

A

The point at which there is no net CO2 uptake. I.e the CO2 produced in respiration = the CO2 used in photsynthesis

36
Q

The light saturation point is what? [2]

A

The value of light intensity which gives the maximum rate of photosynthesis