The Cross Bridge Cycle

Q. As per the sliding filament theory, during muscle contraction the ___________ filament slides over the thick filament.

1. actin
2. myosin
3. collagen
4. creatine

Q. What is the correct sequence of events in the cross bridge cycle?

1. Detachment
2. Formation
3. Power stroke
4. Reactivation

Q. Assertion: Calcium ions play a crucial role in muscle contraction.
Reason: Calcium ions bind troponin causing the displacement of tropomyosin, allowing the myosin head to bind actin.
Select the appropriate option:

1. Both assertion and reason are correct statements and reason is the correct explanation of the assertion
2. Both assertion and reason are correct statements and reason is an incorrect explanation of the assertion
3. Only assertion is correct
4. Both assertion and reason are incorrect

Q. The immediate source of energy for muscle contraction is

1. ATP
2. phosphocreatine
3. glycogen
4. phosphocreatine kinase

Q. What is the location of troponin in the process of muscle fibre contraction?

1. Attached to myosin filament
2. Attached to tropomyosin
3. Attached to myosin cross bridges
4. Attached to T tubule

Q. Which of the following statements is/are correct?
i. Contraction of muscle is an active process.
ii. Relaxation of muscle is an active process.
iii. Calcium is stored in sarcoplasmic reticulum.

1. Both i and ii
2. Both i and iii
3. Only iii
4. Only i

Q. The globular head of mysosin has:
I. ATP binding site
II. Actin binding site
III. Myosin binding site
IV. Troponin binding site
V. Calcium binding

1. I and II
2. I and III
3. I, III and IV
4. I, III, and V

Q. A myosin molecule has two ATP binding sites.

1. False
2. True

Q. A myosin molecule has only one actin binding site.

1. False
2. True

Q. With which of the following molecules does $C{a}^{2+}$ released from the sarcoplasmic reticulum bind?

1. Myosin
2. Actin
3. Troponin
4. Tropomyosin

Q. What is the correct sequence of events in the cross bridge cycle?

1. Detachment
2. Formation
3. Power stroke
4. Reactivation

Q. Which of the following statements is/are correct?
i. Contraction of muscle is an active process.
ii. Relaxation of muscle is an active process.
iii. Calcium is stored in sarcoplasmic reticulum.

1. Both i and ii
2. Both i and iii
3. Only iii
4. Only i

Q.

What is the correct sequence of events in the cross bridge formation?

i. The power stroke

ii. Cross bridge formation

iii. Myosin head is activated by ATP

iv. Calcium released binds to the troponin unblocks the actin sites

v. Cross bridge detachment

vi. Reactivation of the myosin head

1. iv, iii, ii, i, v, vi.

2. i, v, ii, iii, iv, vi.

3. iii, iv, i, v, ii, vi.

4. ii, i, iv, iii, v, vi.