Locomotion and Movement Test

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Locomotion and Movement Test - 1

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Question 1
4 / -1

The slow twitch muscle fibres which are rich in myoglobin and have abundant mitochondria are

A
white skeletal muscles

B
cardiac muscles

C
red skeletal muscles

D
involuntary muscles

Solution

Muscles contain a red coloured pigment called myoglobin that stores oxygen. Some muscles have high content of myoglobin which gives them reddish appearance. Such muscles are called red muscles. Such muscles have abundant mitochondria and show slow rate of contraction for long periods that's why they are called slow twitch muscles.
Question 2
4 / -1

The figures given here represent three different conditions of sarcomeres. Identify these conditions and select the correct option.

A
A - Contracting B - Relax C - Maximally contacted

B
A - Relax B - Contracting C - Maximally contacted

C
A - Maximally contacted B - Contracting C - Relax

D
A - Relax B - Contracting C - Contacting

Solution

In the given figure A, the length of the two sarcomeres is normal i.e., the muscle is in relaxed state. In figure B. the length of sarcomeres, shortens, H-zone narrows and size of l-band decreases i.e., the muscle is contracting. In figure C, the length of sarcomere further shortens and H-zone disappears and l-band further decreases i.e., the muscle is maximally contracted.
Question 3
4 / -1

Which of the following is the contractile protein of a muscle?

A
Tropomyosin

B
Tubulin

C
Myosin

D
All of these

Solution

The contractile protein of a muscle is myosin. Myosin constitutes 55% of muscle protein by weight. The thick filaments consist mainly of myosin protein. A myosin molecule consists of six polypeptide chains, two identical heavy chains and four light chains.
Question 4
4 / -1

If a stimulus, several times greater than the threshold stimulus is provided to a muscle fibre, it will

A
contract with a larger force

B
contract with a smaller force

C
contract with the same force

D
undergo tetany

Solution

A muscle fibre would contract only when it receives stimulation of certain intensity called threshold stimulus. Response of a muscle fibre to a stimulus is not proportional to its intensity. It is absent when the intensity is subliminal. Muscle fibre contracts to the maximum whether the stimulus has threshold value or supraliminal value.
Question 5
4 / -1

Which of the following ions help in muscle contraction?

A
K⁺ and Mg⁺⁺

B
Na⁺ and K⁺

C
Ca⁺⁺ and Na⁺⁺

D
Ca⁺⁺ and Mg⁺⁺

Solution

In muscle contraction, both Ca²⁺ and Mg²⁺ are used. Ca²⁺ helps in the formation of actomyosin by combining actin and myosin proteins. This will provide contraction in muscle. ATPase activity of myosin requires both Ca²⁺ and Mg²⁺. This helps in release of energy. This energy is used up in the contraction of muscle.
Question 6
4 / -1

In a muscle undergoes rapid contraction and relaxation, the sarcoplasmic reticulum extension

A
requires constant plugging in and out of Ca²⁺

B
rapidly synthesise myosin

C
does not require energy all of these.

D
all of these

Solution

Sarcoplasmic reticulum of muscle cells store Ca²⁺ ions. During contracting of muscle, Ca²⁺ ions are released from sarcoplasmic reticulum to sarcoplasm and vice versa occurs during relaxation. Therefore, if a muscle undergoes rapid contraction and relaxation it requires constant plugging in and out of Ca2+ ions from sarcoplasmic reticulum.
Question 7
4 / -1

Which of the following is incorrect regarding muscle contraction?

A
Actin and myosin make actomyosin.

B
Phosphate reserve comes from phosphocreatine.

C
Chemical energy is converted into mechanical energy.

D
Mechanical energy is converted into chemical energy.

Solution

During muscle contraction, chemical energy is converted into mechanical energy.
Question 8
4 / -1

Myoglobin is present in

A
all muscle fibres

B
white muscle fibres

C
red muscle fibres

D
none of these

Solution

Myoglobin (red coloured oxygen storing pigment) is present in all muscle fibres. Red muscle fibres have abundant myoglobin while white muscle fibres have less myoglobin
Question 9
4 / -1

Which of the following is correct regarding changes in muscle fibre from relaxed to contracted state in the given figure?

A
The length of the thick and thin myofilaments has changed

B
Length of both anisotropic and isotropic band has changed

C
The myosin cross-bridges move on the surface of actin and the thin and thick myofilaments slide past each other

D
Length of the sarcomere remains same

Solution

During muscle contraction, the cross-bridge of the myosin of thick myofilaments connect with portions of actin of the thin myofilaments. The myosin and the thin and thick myofilaments slide past each other. Length of A-band remains constant and actin filaments meet in the centre of the sarcomere. The Z-line comes closer and width of l-band decreases.
Question 10
4 / -1

In the resting muscle fibre, tropomyosin partially covers

A
calcium binding sites on troponin

B
actin binding sites on myosin

C
myosin binding sites on actin

D
calcium binding sites on actin

Solution

When the muscle is at rest, the tropomyosin molecule covers the binding site of the actin molecule where interaction with myosin occurs. During contraction of the Tuscte the active site is uncovered, allowing the interaction of actin With myosin.
Question 11
4 / -1

Which one of the following options shown the next stage of muscle contraction after the stage given in question?

A

B

C

D

Solution

The figure in the question shows formation of cross bridge between myosin head and actin filament. Next stage would be the figure showing the sliding/rotation of the head of myosin filament of the actin filament.
Question 12
4 / -1

During muscular contraction, which of the following events occur?
(I) H-zoned is disappeared
(ii) A band widens
(iii) I band reduces in width
(iv) Width of A band is unaffected
(v) M line and Z line come closer.

A
(i), (iii), (iv) and (v)

B
(i), (ii) and (v)

C
(ii), (iv) and (v)

D
(i), (ii) and (iii)

Solution

Muscle contraction is brought about by sliding movement of actin filaments over myosin filaments. When a muscle fibril contracts, ita A band remain constant and I band shortens. H zone also disappears as the actin filaments of both sides in each sarcomere overlap each other at M-line. M-line and Z-line also come closer.
Question 13
4 / -1

Which of the following is the most abundant mineral element in the skeletal muscle?

A
Sodium

B
Calcium

C
Potassium

D
Phosphorous

Solution

Potassium is the most abundant mineral in muscles. It works closely with sodium in muscle function. All other minerals are present only in traces. So, the correct option is 'potassium'.
Question 14
4 / -1

Following is given a randomly arranged list of events that occur at neuromuscular junction to trigger muscle contraction.
(i) Receptor sites on sarcolemma
(ii) Nerve impulse
(iii) Release of Ca⁺² from sarcoplasmic reticulum
(iv) The neurotransmitter acetylcholine is released
(v) Sarcomere shortern
(vi) Synaptic cleft
(vii) Spread of impulses over sarcolemma on TT-tubules
Which of the following gives the correct sequence of these steps?

A
(ii)→(iv)→(i)→(vi)→(vii)→(iii)→(v)

B
(ii)→(iv)→(vi)→(i)→(vii)→(iii)→(v)

C
(i)→(ii)→(iii)→(iv)→(v)→(vi)→(vii)

D
(vii)→(vi)→(v)→(iv)→(iii)→(ii)→(i)

Solution

a. As a nerve impulse( action potential) from a motor neuron arrives via its axon at the neuromuscular junction, the vesicles in the endplate release a neurotransmitter, the acetylcholine, into the nerve-muscle gap (synaptic cleft).
b. Acetylcholine depolarizes the postsynaptic muscle cell's sarcolemma and set up an action potential in the latter.
c. The action potential spreads deep into the interior of the muscle fibre via T- tubules and Z lines.
d. The incoming action potential changes the permeability of the SR, causing to release calcium ions.
e. The calcium ions bind to troponin molecules.
f. The latter change shape and shift position.
So, the correct answer is '(ii) →(iv)→(vi)→(i)→(vii)→(iii)→(v)'.
Question 15
4 / -1

Which of the following is a source of energy for muscle contraction?

A
Actin

B
ATP

C
Myosin

D
Actomyosin

Solution

The energy for muscle contraction is obtained from ATP.