NCERT Solutions for Class 11 Biology Chapter 20 Locomotion and Movement

NCERT Solutions for Class 11 Chapter 20 – Locomotion and Movement can be accessed for free at CoolGyan’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 composed of the content prescribed by the CBSE board, i.e., the information provided in the NCERT textbook for Class 11. NCERT Solutions for Class 11 presents students with solutions to all the chapters in a downloadable format along with the corresponding questions for reference.

Apart from all the other benefits, NCERT Solutions enable students to understand and grasp the answering tactics to effectively answer in the examinations while keeping a track of time. The solutions are reviewed and evaluated thoroughly for its accuracy and preciseness so that the information provided does not digress from the central content.

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Exercise Questions Page Number – 313

1. Draw the diagram of a sarcomere of skeletal muscle showing different regions.

Solution:

The diagram below shows the sarcomere of skeletal muscle showing different regions:

2. Define sliding filament theory of muscle contraction.

Solution:

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.

Solution:

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.

Solution:

(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

Solution:

The differences are as follows:

a) Actin and myosin

b) Red and white muscles

c) Pectoral and Pelvic girdle

6. Match Column I with Column II:

Solution:

7. What are the different types of movements exhibited by the cells of human body?

Solution:

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?

Solution:

The differences between a skeletal muscle and a cardiac muscle is as follows:

9. Name the type of joint between the following:-

(a) atlas/axis

(b) carpal/metacarpal of thumb

(c) Between phalanges

(d) femur/acetabulum

(e) Between cranial bones

(f) Between pubic bones in the pelvic girdle

Solution:

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

Solution:

(a) Seven

(b) Fourteen

(c) Troponin, tropomyosin

(d) Sarcoplasmic reticulum

(e) Eleventh, twelfth

(f) Eight

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 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