Energy and ATP

Question 1

What is energy?

Answer 1

Energy is defined as ‘the ability to do work’.

Question 2

Why do organisms need energy?

Answer 2

Metabolism.
Movement.
Active transport.
Maintenance, repair and division.
Production of substances.
Maintenance of body temperature.

Question 3

The flow of energy through living systems occurs in what three stages?

Answer 3

1. Light energy from the Sun is converted by plants into chemical energy during photosynthesis.
2. The chemical energy from photosynthesis, in the form of organic molecules, is converted into ATP during respiration in all cells.
3. ATP is used by cells to perform useful work.

Question 4

How does ATP store energy?

Answer 4

Adenosine triphosphate has three phosphate groups.
The bonds between these phosphate groups are unstable and so have a low activation energy, which means they are easily broken.
When they do they release lots of energy.

Question 5

What is the equation to show how energy is produced?

Answer 5

ATP + H2O -> ADP + P + E
Hydrolysis.
(Reversible)

Question 6

The synthesis of ATP to ADP involves the addition of a phosphate molecule to ADP. It occurs in what three ways?

Answer 6

• Photophosphorylation- which takes place in chlorophyll- containing plant cells during photosynthesis.
• Oxidative phosphorylation- which occurs in the mitochondria of plant and animal cells during the process of electron transport.
• Substrate- level phosphorylation which occurs in plant and animal cells when phosphate groups are transferred from donor molecules to ADP to make ATP.

Question 7

What is ATP made from?

Answer 7

The nucleotide base adenine
Ribose sugar
Three phosphate groups

Question 8

How is ATP synthesised?

What enzyme catalyses this reaction?

Answer 8

The synthesis of ATP to ADP involves the addition of a phosphate molecule to ADP.
ATP synthase.

Question 9

Name biological processes in plants that require energy.

Answer 9

Photosynthesis
Active transport
DNA replication
Protein synthesis
Cell division

Question 10

What is ATP broken down into by ATPase?

Answer 10

ADP & Pi

Question 11

By what process is ATP broken down?

Answer 11

Hydrolysis

Question 12

What specific properties mean ATP is a good energy source?

Answer 12

ATP stores or releases only a small, manageable amount of energy at a time so none is wasted.
It’s small and soluble so can be easily transported around the cell.
It’s easily broken down, so energy can be easily released.
It can transfer energy to another molecule by transferring one of its phosphate groups.
ATP can’t pass out the cell, so the cell always has an immediate supply of energy.