3.3.2 Photosynthesis Flashcards Preview

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Flashcards in 3.3.2 Photosynthesis Deck (77)
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1

Describe how ATP is synthesised

ATP is synthesised via condensation reaction between ADP and P¡ (inorganic phosphate) using energy from an energy-releasing reaction

2

What enzyme catalyses ATP synthesis?

Enzyme ATP synthase

3

Where is the energy stored in ATP?

Energy is stored as chemical energy in the phosphate bond

4

What happens when ATP arrives (via diffusion) to a part of cell that needs energy?

  • ATP is hydrolysed back into ADP and P¡
  • Chemical energy is released from phosphate bond and used by cell

5

What enzyme catalyses ATP hydrolysis?

ATP hydrolase

6

ADP and P¡ are _____

recycled

7

Draw an ATP molecule

8

Name and explain 6 properties that ATP has that makes it a good energy source

  • Stores or releases only a small, manageable amount of energy at a time
    • ∴ no energy is wasted as heat 
  • It's a small, soluble molecule ∴ it can be easily transported
  • (Easily) broken down in 1 step = energy can easily released instantaneously 
  • It can be quickly re-made
  • Can make other molecules more reactive by transferring one of its phosphate groups to them (phosphorylation)
  • ATP can't pass out of cell = cell always have immediate supply of energy

9

Define a metabolic pathway 

Series of small reactions controlled by enzymes

e.g. respiration and photosynthesis

10

Define Phosphorylation 

Adding phosphate to a molecule

e.g. ADP → ATP

11

Define Photolysis 

Splitting (lysis) of a molecule using light (photo) energy

12

Define Photophosphorylation 

Adding phosphate to a molecule using light

13

Define Photoionisation 

  • When light energy excites electrons in an atom
  • Giving them more energy and causing them to be released
  • Release causes atom to become positively-charged ion

14

Define Hydrolysis 

Splitting (lysis) of a molecule using water (hydro)

15

Define Decarboxylation 

Removal of CO2 from molecule

16

Define Dehydrogenation 

Removal of hydrogen from molecule

17

Chloroplasts contain _________ _____

Photosynthetic pigments

18

What are photosynthetic pigments (e.g. chlorophyll a, chlorophyll b and carotene)?

Coloured substances that absorb light energy

19

Where are pigments found?

Thylakoid membranes = attached to proteins

20

What is a photosystem?

Protein + pigment

21

Name the 2 photosystems used by plants to capture light energy

  • Photosystem I (PSI)
  • Photosystem II (PSII)

22

What are carbohydrates that are produced by photosynthesis and not used straight away stored as and where?

As starch grains in the stroma

23

Where does the the light-dependent reaction occur?

Takes place in thylakoid membranes

24

Photosystems are linked by _____ ____

electron carriers

25

What are electron carriers?

Proteins that transfer electrons

26

Photosystems and electron carriers form an ____ ______ ____

electron transport chain

27

What is an electron transport chain?

Chain of proteins through which excited electrons flow

28

Light-dependent reaction includes 2 types of photophosphorylation. Name them.

  • Non-cyclic Photophosphorylation
  • Cyclic Photophosphorylation

29

Name the 4 main stages in the light-dependent reaction (non-cyclic photophosphorylation). 

  1. Light energy excites electrons in chlorophyll
  2. Photolysis
  3. Energy from excited electrons make ATP...
  4. ... and generates reduced NADP

30

The Light-dependent Reaction

Describe Stage 1

  1. Chlorophyll (PSII) absorbs light
  2. Light energy excites electrons in chlorophyll
    • Electrons move to higher energy level
  3. High-energy electrons are released from chlorophyll and move down electrons transport chain to PSI

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