EN: Photosynthesis, Respiration and ATP

Question 1

Give examples of things plants need energy for:

Answer 1

• Photosynthesis
• Active transport
• DNA replication
• Cell division
• Protein synthesis

Question 2

Give examples of things animals need energy for:

Answer 2

• Muscle contraction
• Maintenance of body temperature
• Active transport
• DNA replication
• Cell division
• Protein synthesis

Question 3

What is the overall equation for photosynthesis?

Answer 3

6CO₂ + 6H₂O + Energy —> C₆H₁₂O₆ + 6O₂

Question 4

Describe photosynthesis in words:

Answer 4

The process where energy from light is used to make glucose from H₂O and CO₂ (light energy is converted to chemical energy in the form of glucose).

Question 5

Where is energy stored in plants?

Answer 5

In the glucose, until it is released by respiration.

Question 6

How do animals obtain glucose?

How do they release energy?

Answer 6

By eating plants/other animals.

Release energy by respiration.

Question 7

Why is respiration useful?

Answer 7

The energy released is used to power all the biological processes in a cell.

Question 8

What are the two types of respiration?

What is the difference?

Answer 8

Aerobic respiration - using oxygen.

Anaerobic respiration - without oxygen.

Question 9

What does aerobic respiration produce?

What is the equation?

Answer 9

Carbon dioxide + water + releases energy.

C₆H₁₂O₆ + 6O₂ —> 6CO₂ + 6H₂O + energy.

Question 10

What does anaerobic respiration produce in plants and yeast?

Answer 10

Glucose —> ethanol and carbon dioxide

Question 11

What does anaerobic respiration produce in humans?

Answer 11

Glucose —> lactate + energy

Question 12

What is ATP?

Answer 12

Adenosine triphosphate.

The immediate source of energy in a cell.

Question 13

Why is ATP needed?

Answer 13

A cell can’t get its energy directly from glucose.

So ATP is needed to carry the energy around the cell to where it’s needed.

Question 14

The energy released from glucose is used to make what?

Answer 14

ATP

Question 15

Briefly describe how ATP is synthesised?

Answer 15

A condensation reaction between ADP and inorganic phosphate, using the energy from an energy-releasing reaction.

Question 16

Where is the energy stored in ATP?

Answer 16

As chemical energy in the phosphate bond.

Question 17

What catalyses the reaction of ATP synthesis?

Answer 17

The enzyme ATP synthase.

Question 18

Draw ATP:

Answer 18

Question 19

What does ATP diffuse to?

What happens next?

Answer 19

The part of the cell that needs energy.

It’s hydrolysed back into ADP and inorganic phosphate. Chemical energy is released from the phosphate bond and used by the cell.

Question 20

What catalyses the breakdown of ATP?

Answer 20

ATP hydrolase.

Question 21

What happens to the products of the hydrolysis of ATP?

Answer 21

ADP and inorganic phosphate are recycled and the process starts again.

Question 22

Why is ATP and good energy source?

Answer 22

• Energy released is small and manageable - so no energy wasted as heat.
• Small, soluble molecule so can be easily transported around the cell.
• Easily broken down so energy can be released instantaneously.
• Quickly re-made.
• Makes other molecules more reactive by phosphorylation.
• Can’t pass out of the cell, so cell always has an immediate supply of energy.

Question 23

Phosphorylation.

Answer 23

The action of one molecule transferring a phosphate group to another molecule.

Question 24

The action of one molecule transferring a phosphate group to another molecule.

Answer 24

Phosphorylation.

Question 25

Metabolic pathway

Answer 25

A series of amll reactions controlled by enzymes.

Question 26

Photophosphorylation

Answer 26

Adding phosphate to a molecule using light.

Question 27

Photolysis

Answer 27

The splitting of a molecule using light energy.

Question 28

Photoionisation

Answer 28

When light energy 'excites' electrons in an atom or molecule, giving them more energy and causing them to be released.

Question 29

Hydrolysis

Answer 29

The splitting of a molecule using water.

Question 30

Decarboxylation

Answer 30

The removal of carbon dioxide from a molecule.

Question 31

Dehydrogenation

Answer 31

The removal of hydrogen from a molecule.

Question 32

Redox reactions.

Answer 32

Reactions that involve oxidation and reduction.

Question 33

A series of amll reactions controlled by enzymes.

Answer 33

Metabolic pathway

Question 34

Adding phosphate to a molecule using light.

Answer 34

Photophosphorylation

Question 35

The splitting of a molecule using light energy.

Answer 35

Photolysis

Question 36

When light energy 'excites' electrons in an atom or molecule, giving them more energy and causing them to be released.

Answer 36

Photoionisation

Question 37

The splitting of a molecule using water.

Answer 37

Hydrolysis

Question 38

The removal of carbon dioxide from a molecule.

Answer 38

Decarboxylation

Question 39

The removal of hydrogen from a molecule.

Answer 39

Dehydrogenation

Question 40

Reactions that involve oxidation and reduction.

Answer 40

Redox reactions.

Question 41

The release of electrons during photoionisation causes what?

Answer 41

The atom or molecule to become a positively-charged ion.

Question 42

Describe reduction:

Answer 42

* The gain of electrons/hydrogen * The loss of oxygen

Question 43

Describe oxidation:

Answer 43

* The loss of electrons/hydrogen * The gain of oxygen

Question 44

Oxidation of one molecule always ...

Answer 44

... involves the reduction of another molecule.

Question 45

Coenzyme

Answer 45

A molecule that aids the function of an enzyme.

Question 46

A molecule that aids the function of an enzyme.

Answer 46

Coenzyme

Question 47

Briefly describe how coenzymes work:

Answer 47

By transferring a chemical group from one molecule to another.

Question 48

What is the coenzyme in photosynthesis? ## Footnote *How does it work?*

Answer 48

NADP. ## Footnote *Transfers hydrogen from one molecule to another - so it can reduce or oxidise a molecule.*

Question 49

Give examples of coenzymes in respiration.

Answer 49

NAD, coenzyme A and FAD.

Question 50

What do the coenzymes used in respiration do?

Answer 50

**NAD and FAD -** transfer hydrogen from one molecule to another - this means they can reduce or oxidise a moleucle. **Coenzyme A -** transfers acetate between molecules.