NCERT Solutions for Class 11 Biology Chapter 20 – Locomotion and Movement can be accessed for free at BYJU’S. For CBSE Class 11 students, NCERT Solutions are the go-to resource. They are an apt tool for all the academic requirements of students as these solutions are in accordance with the latest term – II CBSE Syllabus for the 2021-22 academic session. NCERT Solutions for Class 11 presents students with solutions to all the chapters in a downloadable format along with the corresponding questions for reference.
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Access Answers to NCERT Class 11 Biology Chapter 20 – Locomotion and Movement
Exercise Questions Page Number – 313
1. Draw the diagram of a sarcomere of skeletal muscle showing different regions.
The diagram below shows the sarcomere of skeletal muscle showing different regions:
2. Define sliding filament theory of muscle contraction.
Sliding filament theory states that the muscle fibre contraction occurs due to the sliding of the thin filaments over thick filaments.
3. Describe the important steps in muscle contraction.
The mechanism of muscle contraction is explained well by the sliding filament theory which states that the muscle fibre contraction occurs due to the sliding of the thin filaments over the thick filaments.
Mechanism of muscle contraction:
Step 1 – Depolarization of Sarcolemma
1. The central nervous system (CNS) sends a signal through a motor neuron which arrives at the neuromuscular junction or the motor end plate
2. The junction present between the sarcolemma of the muscle fiber and the motor neuron is called the neuromuscular junction
3. The release of a neurotransmitter called acetylcholine is triggered when the signal arrives at the neuromuscular junction. The action potential in the sarcolemma is set by this release.
Step 2 – Release of Calcium ions
1. The sarcolemma transmits the action potential to the sarcoplasmic reticulum in order to release the calcium ions in the sarcoplasm
Step 3 – Conformational changes occurs in the Actin filaments
1. The calcium ions that are released, tends to bind to the troponin and tropomyosin located on the active filaments
2. This linkage causes a modification in the three-dimensional structure of the actin-troponin-tropomyosin complex. The active site for myosin which is located on the actin filament is exposed.
Step 4 – Activation of Myosin heads
1. The calcium ions release causes the myosin heads to get activated which inturn causes the release of energy in the form of ATP
2. Hydrolysis of ATP releases energy which causes the binding of myosin heads to the active sites found on the actin filaments hence forming a cross-bridge
Step 5 – Actin Filaments slide over Myosin
1. The myosin head rotates due to the formation of cross-bridge, pulling the actin filaments to the centre of the A-band which is the H-zone
2. The z-line which is attached to the actin filaments is pulled inwards too
3. Contraction of sarcomere occurs when the actin filaments are pulled in the opposite ends
4. During the process of contraction, the I-band shortens whereas the A-band maintains its length causing the muscles to contract.
4. Write true or false. If false change the statement so that it is true.
(a) Actin is present in thin filament
(b) H-zone of striated muscle fibre represents both thick and thin filaments.
(c) Human skeleton has 206 bones.
(d) There are 11 pairs of ribs in man.
(e) Sternum is present on the ventral side of the body.
(a) Actin is present in thin filament – True
(b) H-zone of striated muscle fibre represents both thick and thin filaments – False
Corrected statement: H-zone of the striated muscle fiber represents only thick filaments
(c) Human skeleton has 206 bones – True
(d) There are 11 pairs of ribs in man – False
Corrected statement: There are 12 pairs of ribs in man.
(e) Sternum is present on the ventral side of the body – True
5. Write the difference between:
(a) Actin and Myosin
(b) Red and White muscles
(c) Pectoral and Pelvic girdle
The differences are as follows:
a) Actin and myosin
|Thin filaments (I-bands) of the myofilament are formed||Thick filaments (A-bands) of the myofilament are formed|
|It is built of globular actin monomers||It is built of meromyosin monomers|
|The regulatory proteins Tropnin and tropomyosin are linked with the actin||The regulatory proteins are not linked, instead each of the meromyosin is built of four light chains and two identical heavy chains|
b) Red and white muscles
|Parameters||Red muscles||White muscles|
|Amount of sarcoplasmic reticulum||Moderate||High|
|Fibers||Narrow and thin||Broad and thick|
|Type of respiration from which energy is derived||Aerobic||Anaerobic|
c) Pectoral and Pelvic girdle
|Pectoral girdle||Pelvic girdle|
|Pectoral girdle is called as the shoulder girdle||Pelvic girdle is called as the hip girdle|
|Each part/half of the girdle consists of two bones – clavicle and scapula||Each part/half of the girdle consists of three bones – ischium, ilium and pubis|
|Forelimb articulation is offered||Hindlimb articulation is offered|
|Head of the humerus articulates with the glenoid cavity of the pectoral girdle||Head of the femur articulates with the acetabulum of the pelvic girdle|
6. Match Column I with Column II:
|Column I||Column II|
|(a) Smooth muscle||(i) Myoglobin|
|(b) Tropomyosin||(ii) Thin filament|
|(c) Red muscle||(iii) Sutures|
|(d) Skull||(iv) Involuntary|
|Column I||Column II|
|(a) Smooth muscle||(iv) Involuntary|
|(b) Tropomyosin||(ii) Thin filament|
|(c) Red muscle||(i) Myoglobin|
|(d) Skull||(iii) Sutures|
7. What are the different types of movements exhibited by the cells of human body?
Movement is considered to be one of the fundamental characteristics which is observed in the living entities. The different types of movements exhibited by the human body cells are:
1. Amoeboid Movement – Leucocytes found in blood exhibit this type of movement. Leucocytes from the circulatory system move towards the injury site when there is a damage to the tissue in order to initiate an immune response.
2. Muscular movement – The muscle cells exhibit this type of movement
3. Ciliary movement – Sex cells (sperms and ova) exhibit this type of movement. This movement facilitates the passage of ova via the fallopian tube on its way to the uterus.
8. How do you distinguish between a skeletal muscle and a cardiac muscle?
The differences between a skeletal muscle and a cardiac muscle is as follows:
|Skeletal muscle||Cardiac muscle|
|Linked to the primary bones||Located in the walls of the heart|
|Voluntary in nature||Involuntary in nature|
|Peripherally located nucleus||Centrally located nucleus|
|The muscle fibers of the skeletal muscles are unbranched||The muscle fibers of the cardiac muscles are branched|
|Intercalated discs are not found in the Muscle fibers of the skeletal muscles||Intercalated discs are found in the muscle fibers of the cardiac muscles|
|Brings about the locomotory actions of the body and maintains body posture||Responsible for the movement/motion of the heart|
9. Name the type of joint between the following:-
(b) carpal/metacarpal of thumb
(c) Between phalanges
(e) Between cranial bones
(f) Between pubic bones in the pelvic girdle
The types of joints are as follows:
(a) atlas/axis – Pivot joint
(b) carpal/metacarpal of thumb – Saddle joint
(c) Between phalanges – Hinge joint
(d) femur/acetabulum – Ball and socket joint
(e) Between cranial bones – Fibrous joint
(f) Between pubic bones in the pelvic girdle – cartilaginous joint
10. Fill in the blank spaces:
(a) All mammals (except a few) have __________ cervical vertebra.
(b) The number of phalanges in each limb of human is __________
(c) Thin filament of myofibril contains 2 ‘F’ actins and two other proteins namely____ and _____.
(d) In a muscle fibre Ca++ is stored in __________
(e) __________ and __________ pairs of ribs are called floating ribs.
(f) The human cranium is made of __________ bones
(c) Troponin, tropomyosin
(d) Sarcoplasmic reticulum
(e) Eleventh, twelfth
List of subtopics covered in Chapter 20 – Locomotion and Movement
|20.1||Types of Movement|
|20.5||Disorders of Muscular and Skeletal System|
NCERT Solutions for Class 11 Biology Chapter 20 – Locomotion and Movement
Locomotion and movement are some of the features exhibited by living entities, except for plants who are immobile. In previous years students would have studied the basics of locomotion and movement. In Class 11, getting deeper into the topic, students are enlightened furthermore about the mechanism of locomotion and other related concepts.
Movement is one of the significant features of living beings. Plants and animals exhibit a wide range of movements. Locomotion is a voluntary movement. Organisms move for different purposes, in search of food, shelter, away from predators, etc. Animals vary in the methods of their locomotion. The chapter of the term – II CBSE Syllabus (2021-22) briefs about the different structures used for locomotion, their mechanism, the skeletal system, joints, the various disorders of the skeletal system, and the muscular system.
Key Features of NCERT Solutions for Class 11 Biology Chapter 20 – Locomotion and Movement
- NCERT Solutions are framed with textbook-based content
- Easy to understand and simple to grasp concepts
- Use of relevant analogies wherever necessary
- Use of neatly labelled diagrams supporting the concept
- Use of pointers and tables wherever required
Frequently Asked Questions on NCERT Solutions for Class 11 Biology Chapter 20
Explain the types of movements exhibited by the cells of the human body in the Chapter 20 of NCERT Solutions for Class 11 Biology.
1. Muscular movement – The muscle cells exhibit this type of movement.
2. Amoeboid movement – Leucocytes found in blood exhibit this type of movement. Leucocytes from the circulatory system move towards the site of injury when there is damage to the tissue to increase immune response.
3. Ciliary movement – Sex cells exhibit this type of movement. It facilitates the passage of ova through the fallopian tube on the way to uterus.
What topics/subtopics are covered in the Chapter 20 of NCERT Solutions for Class 11 Biology?
20.1 – Types of Movement
20.2 – Muscle
20.3 – Skeletal System
20.4 – Joints
20.5 – Disorders of Muscular and Skeletal System