muscle contraction exam qs

Question 1

Use the information provided to describe how you could produce a calibration curve for
creatinine.

Answer 1

1- Use (distilled) water and creatinine solution to produce dilutions (series);
2. Add (creatinine-)detecting solution (to each solution);
3. Using a known volume of a solution
4. Record absorbance of solution using a colorimeter;

Question 2

Describe how you would determine the concentration of creatinine in a urine sample using
your calibration curve.

Answer 2

1 - Add (creatinine-)detecting solution (to urine);
2. Read off concentration against absorbance value obtained

Question 3

During vigorous exercise, the pH of skeletal muscle tissue falls. This fall in pH leads to a
reduction in the ability of calcium ions to stimulate muscle contraction.
Suggest how.

Answer 3

Low pH changes shape of calcium ion receptors
2. Fewer calcium ions bind to tropomyosin;
3. Fewer tropomyosin molecules move away

Question 4

The leg muscles of long-distance cyclists are usually larger than the leg muscles of
non-athletes.
Suggest why.

Answer 4

No (overall) change in number of fibres.
2. Increase in diameter of fibres;
3. (Due to) exercise;

Question 5

If myosin molecules are unable to bind to other myosin molecules, this prevents muscle
contraction.
Use the diagram and your knowledge of how muscles contract to suggest why.

Answer 5

Can’t form myosin
2. Can’t pull actin
3. Myosin moves