skeletal muscles exam questions

Question 1

The diagram below shows the banding pattern of a single sarcomere.
(a)
Q2.
Explain the banding pattern shown in the diagram above. (3)

Answer 1

light band- only actin
H zone- only myosin
darkest region- actin and myosin

Question 2

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 (3)

Answer 2

low pH changes shape of calcium ion receptirs
fewer calcium ions bind to tropomyosin
fewer tropomyosin molecules moved away
fewer binding sites on actin revealed
fewer cross bridges formed

Question 3

(b)
Q6.
(a)
Describe the roles of calcium ions and ATP in the contraction of a
myofibril. (5)

Answer 3

calcium ions diffuse into myofibril from sacroplasmic reticulum
move troopmyosin
expose binding sites on actin
myosin head binds to binding sites on actin
hydrolysis of ATP cause myosin head to bend
pulling actin molecules
attachment of new ATP molecule to each myosin head causes myosin to dettach