ATP

Question 1

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

A

2

36

B

4

31

C

6

29

D

8

26

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

Answer 1

pecies / 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;

Question 2

for the muscle contraction practical what are observations and why

Answer 2

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;