3.5.1.1 - Photosynthesis (Light Dependent Reactions) Flashcards

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1
Q

Describe how NADP+ is reduced in the LDR of photosynthesis.

A

2e- from electron carrier protein (originally from chlorophyll) are gained.

H+ is gained from stroma.

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2
Q

What are the products of the light dependent reactions of photosynthesis?

A

ATP

NADPH (Reduced NADP)

Oxygen

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3
Q

Identify the labels.

A
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4
Q

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5
Q

Why is ATP sometimes referred ot as an immediate energy source of energy?

A

Because only one bond needs ot be broken to release energy.

ATP is rapidly resynthesised.

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6
Q

In biology what is meant by OXIDATION?

A

The loss of electrons

The loss of hydrogen

The gain of oxygen

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7
Q

Identify the labels.

A
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8
Q

For what are the products of the light dependent reactions used for?

A

NADPH and ATP are required in the light independent reacitons of photosynthesis (Calvin cycle)

Oxygen is used in respiraiton or exits the plant via the stomata.

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9
Q

Why does the plant need to carry out the Calvin cycle and respiration if the light dependent reactions produce ATP?

A

Not enough ATP is produced.

ATP is difficult to transport around the plant.

ATP can not be produced in the dark.

Not all plant cells contain chlorophyll

ATP is not a stable store of energy.

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10
Q

Identify the labels.

A
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11
Q

In biology, what is meant by REDUCTION?

A

The gain of electrons.

The gain of hydrogen.

The loss of oxygen.

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12
Q

Describe the Light Dependent Reactions of photosynthesis.

A
  1. Light enters chloroplast and excites 2 electrons in chlorophyll transmembrane protein (photosystem II) spanning thylakoid membrane.
  2. 2e- leave PSII (oxidation) and move to Proton pump (reduction).
  3. Proton pump actively transports H+ from stroma into thylakoid space creating an electrochemical gradient.
  4. 2e- leave Proton pump (oxidation) and move to electron carrier (PSI - reduction).
  5. H+ ions in thylakoid space diffuse through ATP Synthase, providing the energy to catalyse the formation of ADP + Pi -> ATP
  6. 2e- and H+ move onto NADP+ to make NADPH (reduced NADP).
  7. Chlorophyll’s 2e- are replaced via the photolysis of water in the thylakoid space to give 2e- + 2H+ + 1/2O2
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13
Q

Identify the labels.

A
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14
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15
Q

What does the diagram show?

A

The thylakoid membrane of a chloroplast.

Where the light dependent reactions of photosynthesis take place.

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16
Q

What is NADP+?

A

A coenzyme that works alongside an enzyme, in this case it is a hydrogen carrier and electron acceptor.

It works alongside the enzyme: dehydrogenase

17
Q

How can we measure the rate of the light dependent reactions of photosynthesis?

A

Measure the volume of oxygen produced.

Over time.

18
Q

In the light-dependent reaction of photosynthesis, light energy generates ATP. Describe how. (5 marks)

A
  1. Light (energy) excites / raises energy level of electrons in chlorophyll;
  2. Electrons pass down electron transfer chain;
  3. (Electrons) reduce carriers / passage involves redox reactions;
  4. Electron transfer chain / role of chain associated with chloroplast
    membranes / in thylakoids / grana;
  5. Energy released / carriers at decreasing energy levels;
  6. ATP generated from ADP and phosphate / Pi / phosphorylation of ATP;
19
Q

When investigating how light intensity affects plant growth what variables should you control?

A

temperature

concentration carbon dioxide

volume of water

concentation of ions in soil

pH of soil