ATP

Question 1

Cells constantly hydrolyse ATP to provide energy.

(a) Describe how ATP is resynthesised in cells.

Answer 1

From ADP and phosphate;

Accept

Reject P/Phosphorus

Reject use of water in the reaction

2. By ATP synthase;
3. During respiration/photosynthesis;

Question 2

Give two ways in which the hydrolysis of ATP is used in cells.

Answer 2

To provide energy for other reactions/named process;

Reject ‘produce’ energy

2. To add phosphate to other substances and make them more reactive/change their shape;

Question 3

Hydrolysis of ATP is catalysed by the enzyme ATP hydrolase.

A student investigated the effect of ATP concentration on the activity of ATP hydrolase. She used shortening of strips of muscle tissue caused by contraction as evidence that ATP was being hydrolysed.

• She took four slides A, B, C and D, and added strips of muscle tissue of the same length to each slide.
• She then added the same volume of ATP solutions of different concentrations to the four slides and left each slide for five minutes.
• She then recorded the final length of each strip of muscle tissue.

Her results can be seen in the table.

Slide

Concentration of ATP solution added to slide / × 10–6 mol dm–3

Final length of muscle tissue after 5 minutes / mm

(c) Other than those given, name two variables the student should have controlled.

Describe and explain the pattern shown by the data in the table.

Answer 3

Species / organism the muscle tissue came from;

OR

Thickness / type / source of the muscle tissue;

Ignore surface area of muscle tissue

2. Temperature of the muscle tissue / ATP solution / slides;

Need to be qualified

3. pH of the ATP solution;

Description

1. As concentration of ATP increases, length of muscle decreases;

Accept negative correlation

Explanation

2. More ATP (hydrolysed by ATP hydrolase), so more energy released, so more muscle contraction / shortening of muscle;