CBSE Class 11 Biology VBQs Locomotion And Movement

Question. Which is a false statement about skeletal muscle structure?
(a) A myofibril is composed of multiple muscle fibres.
(b) Most skeletal muscles attach to bones byconnec tive tissue tendons.
(c) Each end of a thick filament is surrounded by six thin filaments.
(d) A cross-bridge is a portion of the myosin molecule.

Answer : A

Question. The protein whose removal enables myosin to bind actin in smooth muscle is
(a) tropomyosin
(b) caldesmon
(c) myosin light chain kinase
(d) calmodulin.

Answer : A

Question. Rigor mortis is
(a) contraction of muscles after death
(b) contraction of muscles before death
(c) shivering of muscles
(d) none of these.

Answer : A

Question. White fibres differ from red fibres in having
(a) high number of mitochondria
(b) high amount of myoglobin
(c) high quantity of ATP
(d) high quantity of sarcoplasmic reticulum.

Answer : D

Question. During muscle contraction, the length of ___________ reduces.
(a) sarcomere
(b) myofilaments
(c) A-band
(d) all of these

Answer : A

Question. Upon stimulation of skeletal muscles calcium is immediately made available for binding to troponin from
(a) blood
(b) lymph
(c) sarcoplasmic reticulum
(d) bone.

Answer : C

Question. Study the following diagram and select the correct options for X, Y and Z.
          X             Y               Z
(a) F-actin    Troponin    Tropomyosin
(b) Troponin Tropomyosin F-actin
(c) Tropomyosin Troponin F-actin
(d) Tropomyosin F-actin Troponin

Answer : D

Question. Immediate source of energy for musclecontra ction is
(a) glucose
(b) GTP
(c) ATP
(d) creatine phosphate.

Answer : C

Question. Which of the following correctly characterises as a “fast-oxidative” type of skeletal muscle fibre?
(a) Few mitochondria and high glycogen content.
(b) Low myosin ATPase rate and few surrounding capillaries.
(c) Low glycolytic enzyme activity and intermediate contraction velocity.
(d) High myoglobin content and intermediate glycolytic enzyme activity.

Answer : D

Question. In which of the following step of musclecontraction e nergy is utilised in the form of ATP?
(a) Back flow of calcium ion into sarcoplasmic reticulum
(b) Formation of cross bridge
(c) Breaking of cross bridge
(d) All of these

Answer : D

ASSERTION REASON QUESTIONS

Directions : These questions consist  of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following five responses.
(a) If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
(b) If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
(c) If the Assertion is correct but Reason is incorrect.
(d) If both the Assertion and Reason are incorrect.
(e) If the Assertion is incorrect but the Reason is correct.

Question. Assertion: Fatigue is inability of muscle to relax.
Reason: It is due to lactic acid accumulation by repeated contractions. 
Answer. A

Directions  : Each of these questions contains an Assertion followed by Reason. Read them carefully and answer the question on the basis of following options. You have to select the one that best describes the two statements.
(a) If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.
(b) If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.
(c) If Assertion is correct but Reason is incorrect.
(d) If both the Assertion and Reason are incorrect.

Question. Assertion : Ball and socket joints are the most mobile joints.
Reason : Synovial fluid is present here.
Answer. B

Question. Assertion : Intercalated discs are important regions of cardiac muscle cells.
Reason : Intercalated discs function as boosters for muscle contraction waves. 
Answer. A

Question. Assertion : Arthritis or inflammation of a joint makes the joint painful.
Reason : Some toxic substances are deposited at the joint.
Answer. C

Question. Assertion : The phase of muscle contraction occurs when myosin binds and releases actin.
Reason : Muscle contraction is initiated by a signal sent by the peripheral nervous system via motor neuron. 
Answer. C

Question. Assertion : Inflammation of a skeletal joint may immobilize the movements of the joint.
Reason : Uric acid crystals in the joint cavity and ossification of articular cartilage lead to this.
Answer. A

Very Short Answer Type Questions

Question. Locomotion requires a perfect coordinated activity of muscular, _____ and _______ systems.

Answer. Skeletal, neural

Question. Name the tissue which has intercalated disc. What is its function?

Answer. Cardiac muscle tissue has intercalated discs. Intercalated discs support synchronised contraction of cardiac tissue.

Question. State the cause and symptoms of tetany.

Answer. Tetany is caused due to low Ca2+ in body fluid. This results in rapid spasms or wild contractions in muscles.

Question. What is the functional unit of a muscle?

Answer. Sarcomere is the functional unit of muscles.

Short Answer Type Questions

Question. Define muscles. What are the special properties of muscle tissue?

Answer. Muscle is a specialised tissue of mesodermal origin that constitutes about 40-50 percent of the body weight of a human adult. Special properties of muscle tissue are excitability, contractility, extensibility and elasticity.

Question. Classify the muscles based on following criteria and give examples for each.
(a) Location
(b) Appearance
(c) Nature of regulation

Answer. (a) On the basis of their presence at different locations, muscles can be classified as: (i) Skeletal muscles – muscles present in limbs, pharynx, etc. (ii) Visceral muscles – muscles found in stomach, lung, etc. (iii) Cardiac muscles – muscles in wall of heart. (b) Based on their appearance, muscles are of following types : (i) Striated or striped muscles – skeletal and cardiac muscles. (ii) Non striated or unstriped muscles – visceral (smooth) muscles. (c) Action of muscles are regulated differently, hence they are classified as : (i) Voluntary muscles – Skeletal muscles. (ii) Involuntary muscles – Visceral muscles and cardiac muscles.

Question. Differentiate between skeletal and visceral muscles.

Answer. Following are the differences between skeletal and visceral muscles :

Question. Name the type of involuntary muscles in human. Why they are involuntary in nature? Where are such muscles present?

Answer. Visceral or smooth muscles are involuntary muscles. These are involuntary in nature as their activity is controlled by the autonomic nervous system and are not under the control of the animal’s will. Involuntary muscles are present in urinary bladder, iris of an eye, blood vessels, etc.

Question. Write a short note on the role of calcium ions and ATP in muscle contraction.

Answer. Release of calcium ions from sarcoplasmic reticulum trigger the muscle contraction process. The calcium ions result in movement of troponin and tropomyosin on their thin filaments, and this enables the myosin molecule heads to ‘grab and swivel’ their way along the thin filament, this is the driving force of muscle contraction. Energy for contraction of muscle fibre is provided by ATP which is produced by creatine phosphate and respiratory breakdown of glycogen or glucose.

Question. What are the major changes that occur in a sarcomere during muscle contraction?

Answer. As a muscle contracts, following changes occur in sarcomere: (i) the thin myofilaments slide inward towards the H-zone (ii) the Z lines come closer together (iii) the width of the I bands decreases (iv) the width of the H zones decreases (v) there is no change in the width of the A band.

Question. Briefly describe the structure of a sarcomere.

Answer. The sarcomere is the functional unit of myofibril. A myofibril has dark and light bands. The dark bands are called A-bands and light bands are called I-bands. At centre of A-band, less dark zone, H-zone is present. Each I-band has at its centre a dark membrane called Z-line. The part of myofibril between two successive Z-lines is called sarcomere.

Long Answer Type Questions

Question. Write a brief note on myofilament of sarcomere.

Answer. Sarcomere comprises of number of parallely arranged filaments called myofilaments. A myofilament has alternate dark and light bands. The dark band corresponds to ‘A-band’, made up of protein myosin and light band is ‘I-band’, comprising of protein actin. Each myosin (thick) filament is a polymerised protein made of many monomeric proteins called meromyosins. Each meromyosin has two important parts - a globular head with a short arm, termed as heavy meromyosin (HMM) and a tail; called light meromyosin (LMM). The HMM component projects outwards at an angle from a polymerised myosin filament at regular distance, and popularly known as cross arms. The globular head is an active ATPase enzyme which has sites for attachment with ATP and actin. Each actin filament is made of two ‘F’ actins helically wound to each other. Each ‘F’ actin is a polymer of monomeric G-actins. Actin also contains two filaments of another protein, tropomyosin, running close to F-actins throughout the length and troponin distributed at regular intervals on the tropomyosin.