ATP

Question 1

State and explain 6 reasons why organisms need energy

Answer 1

1) metabolism -all reactions in organisms involve energy
2) movement - within organism (eg blood circulation) and movement of the organism itself (eg locomotion)
3) active transport - of ions against a concentration gradient
4) maintenance, repair and division - of cells and organelles
5) production of substances (eg enzymes and hormones)
6) maintenance of body temperature in birds and mammals (endothermis)

Question 2

Define energy

Answer 2

‘The ability to do work’

Question 3

Describe the 3 stages of the flow of energy through living systems

Answer 3

1) light energy from sun is converted by plants to chemical energy by photosynthesis
2) Chemical energy from photosynthesis (in the form of organic molecules) is converted to ATP during cell respiration
3) ATP is used by cells to perform useful work

Question 4

State the equation for the hydrolysis of ATP

Answer 4

ATP + H2O —> ADP + Pi + Energy

Adenosine Triphosphate + Water –> Adenosine Diphosphate + Inorganic Phosphate + Energy

Question 5

Name and explain the 3 ways ADP can be phosphorylated

Answer 5

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

Question 6

Name and describe some roles of ATP

Answer 6

• metabolic processes - to build macromolecules from their basic units
• movement - providing energy for muscle contraction
• active transport - change shape of carrier proteins in membrane
• secretion - needed to form lysosomes (for secretion of cell products)
• activation of molecules - when a molecule gains a phosphate group from ATP hydrolysis, it becomes more reactive and is activation energy is lowered