2.1 Energy and ATP

Question 1

EXAM QUESTION

ATP is useful in many biological processes. Explain why. (4)

Answer 1

1. Releases energy in small /
manageable amounts;
2. (Broken down) in a one step /
single bond broken;
3. Immediate energy
compound/makes energy
available rapidly;
4. Phosphorylates/adds
phosphate;
5. Makes (phosphorylated
substances) more reactive /
lowers activation energy;
6. Reformed/made again;

Question 2

EXAM QUESTION

Write a simple equation to show how ATP is synthesised from ADP. (1)

Answer 2

ADP + Pi —> ATP

Question 3

EXAM QUESTION

Give two ways in which the properties of ATP make it a suitable source of energy in biological processes (2)

Answer 3

1. Energy released in small/suitable amounts;
2. Soluble;
3. Involves a single/simple reaction;

Question 4

EXAM QUESTION

Humans synthesise more than their body mass of ATP each day. Explain why it is necessary for them to synthesise such a large amount of ATP. (2)

Answer 4

1. ATP is unstable;
2. ATP cannot be stored / is an immediate source of energy;
3. Named process uses ATP ;
4. ATP only releases a small amount of energy at a time;

Question 5

Energy:

Define energy
give 4 properties (4)

Answer 5

= the ability to do work

Different forms (e.g. light, heat, sound)
Can be changed from one form to another.
Cannot be created or destroyed.
Measured in joules (J)

Question 6

Flow of energy through living systems (3)

Answer 6

1. Light energy from Sun converted into chemical energy in photosynthesis.
2. Chemical energy converted into ATP in respiration.
3. ATP is used by cells to do work.

Question 7

How ATP stores energy

Adenosine triphosphate (ATP) has?
Bonds between phosphate groups? because? (2)
When they break, they?
What type of reaction?
Equation?

Answer 7

Three phosphate groups. 
Easily broken:
Unstable 
Low activation energy
Release lots of energy
Hydrolysis reaction = water is used to convert ATP to ADP.
ATP ---> ADP + Pi

Question 8

Synthesis/re-formation of ATP

Why is synthesis/re-formation of ATP possible?
What type of reaction?
Equation?

Answer 8

Conversion of ATP to ADP reversible reaction.
Condensation reaction = Water is removed to convert ADP to ATP.
ADP + Pi —> ATP

Question 9

Synthesis/re-formation of ATP

Three ways: 2 for each
Photophosphorylation
Oxidative phosphorylation
Substrate-level phosphorylation

Answer 9

Photophosphorylation
Etc
Photosynthesis
Oxidative phosphorylation 
Krebs and etc
Respiration
Substrate-level phosphorylation
Glycolysis 
Respiration

Question 10

ATP continually synthesised because:
Bad long-term energy source?
Cannot be?
Good immediate energy source? (3)

Answer 10

Bad long-term energy store
Phosphate bonds easily broken - unstable, low activation energy
Cannot be stored/ is an immediate energy source
Good immediate (rapid) energy source because:
Energy released in small/suitable amounts.
Hydrolysis of ATP to ADP is a single/simple reaction
Soluble

Question 11

4 things ATP is the source of energy for? (4)

Answer 11

Activation of molecules - adds phosphate to other molecules - makes more reactive, lowers activation energy
Active transport - changes shape of carrier proteins in plasma membranes
Metabolism/synthesis - builds up macromolecules from their basic units (e.g. polysaccharide synthesis from monosaccharides)
Movement (e.g. muscle contraction, blood circulation, locomotion)