Excitation Contraction Coupling

Q. During muscle contraction, which of the following shortens?
(i) A band
(ii) I band
(iii) Sarcomere

1. i and ii
2. ii and iii
3. i and iii
4. i, ii, and iii

Q.

Define the sliding filament theory of muscle contraction.

Q.

Describe the important steps in muscle contraction.

Q. Which of the following regions decreases in length during muscle contraction?

1. 2 and 3
2. 3 and 4
3. 1, 2, and 4
4. 2, 3, and 4

Q.

Nissl granules occur in which part and what is their function?

1. Neurons and site of protein synthesis

2. Blood helps in the nutrition and excretion

3. Sarcoplasm and help in the contraction

4. Cell and secrete mucous

Q. Select the correct option:
i) Muscle contraction takes place by sliding of thick filaments over thin filaments.
ii) When the neural signal reaches the neuromuscular junction, it releases acetylcholine, which helps generate an action potential in the muscle fibre.
iii) Muscle contraction begins by a signal sent by the peripheral nervous system by a motor neuron.

1. Only i is correct
2. Only ii and iii are correct
3. Only ii is correct
4. All are correct

Q. Write down the biochemical events in the mechanism of muscle contraction

Q. Sarcolemma is

1. The Cell membrane that encloses each muscle cell, specifically muscle cells

2. The specialized type of smooth ER that regulates the calcium ion concentration in the cytoplasm of striated muscle cells.

3. A network of membranous tubules within the cytoplasm of a eukaryotic cell

4. All of the above

Q.

Discuss the role of Ca2+ ions in muscle contraction. Draw neat sketches to illustrate your answer.

Q.

Explain sliding filament theory of muscle contraction with neat sketches.

Q.

Sarcolemma, sarcoplasm and sarcoplasmic reticulum refer to particular type of cell in our body. Which is the cell and to what parts of that cell do these names refer to ?

Q.

During muscle contraction, Ca++ ions bind to

1. myosin

2. actin

3. troponin

4. tropomyosin

Q. What happens when the calcium ion level increases in the sarcoplasm?

1. Filament sliding occurs
2. Filament sliding stops
3. Muscle relaxes
4. No change in muscle state

Q. Calcium ions are stored in _____________ in a muscle fibre.

1. sarcoplasmic reticulum
2. all of the above
3. mitochondria
4. golgi bodies

Q.

Are cytoskeleton organelles?

Q. The junction between a motor neuron and the sarcolemma of the muscle fibre is called the neuromuscular junction.

1. False
2. True

Q.

Which of the following changes occur when skeletal muscle contracts?

1. The I- bands shorten

2. The A- bands shorten

3. The Z- lines move further apart

4. The H- zone becomes more visible

Q. The given figure represents the cross bridge cycle in skeletal muscles. What does the step B in the figure represent?

1. Attachment of myosin head to actin forming cross bridge.
2. Splitting of ATP into ADP and Pi. Myosin cocks into its high energy conformation.
3. Attachment of new ATP to myosin head. The cross bridge detaches.
4. Release of phosphate. Myosin changes shape to pull actin.

Q.

• What is x- body?

Q.

Calcium ion concentration in blood affects muscle contraction. Does it lead to tetany in certain cases? How will you correlate fluctuation in blood calcium with tetany?

Q. A network to tubular structure spread throughout the cytoplasmic region is called …………

1. Lysosomes
2. Endoplasmic reticulum
3. Golgi-complex
4. Ribosomes

Q.

how do the oestoblast, oestocytes, and oestoclasts differ frm each other

Q. What will happen to a muscle fibre when it is constantly acted upon by stimuli?

1. The muscle stops contracting
2. Tetanic contraction
3. The duration of response decreases
4. None of the above

Q.

Define sliding filament theory of muscle contraction.

Q.

Rahul exercises regularly by visiting a gymnasium. Of late he is gaining weight. What could be the reason? Choose the correct answer and elaborate.

(a) Rahul has gained weight due to accumulation of fats in body

(b) Rahul has gained weight due to increased muscle and less of fat

(c) Rahul has gained weight because his muscle shape has improved

(d) Rahul has gained weight because he is accumulating water in the body

Q. $F_1$ particles participate in the synthesis of

Q. What is muscle tonus?explain it in detail please.

Q.

When a muscle is at rest, Ca++ ions are concentrated within the spaces of the

1. actin filaments

2. myosin filaments

3. Z lines

4. sarcoplasmic reticulum

Q.

At the neuromuscular junction, nerve impulses are carried across synaptic cleft by neurotransmitters.

1. sarcoplasm, sarcoplasmic reticulum, calcium ions

2. sarcoplasmic reticulum, terminal cisternae, sarcoplasm

Q. Neurotransmitter release occurs through the process of

1. exocytosis
2. endocytosis
3. synapsis
4. excitation