Class 11 Biology NCERT Solutions For Chapter 20 Locomotion and Movement

NCERT Solutions for Class 11 Biology Chapter 20: NCERT Grade 11 Biology, Chapter 20, Locomotion and Movement is a part of Unit 5, Human Physiology. Unit 5 is a combination of 7 chapters and holds a total weightage of 20% in the NEET examination and 18 marks in the final examination.

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 Get 100 percent accurate NCERT Solutions for Class 11 Biology Chapter 20 (Locomotion and Movement) solved by expert Biology teachers. We provide solutions for questions given in Class 11 Biology text-book as per CBSE Board guidelines from the latest NCERT book for Class 11 Biology.

NCERT Solutions for Class 11 Biology Chapter 20 Locomotion and Movement

 

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Download NCERT Class 11 Biology Chapter 20 Solutions

For CBSE Class 11 students, NCERT solutions are the go-to resource. They are an apt tool for all the academic requirements of students. The solutions are reviewed and evaluated thoroughly for its accuracy and preciseness so that the information provided does not digress from the central content.

About NCERT Solutions for Class 11 Biology Chapter 20 Locomotion and Movement

NCERT Grade 11 Biology Chapter 20, Locomotion and Movement is from Unit 5, Human Physiology. Different forms of locomotion in unicellular organisms as well as in humans is discussed in this chapter. Types of Movement, Muscle, Skeletal System, Joints and Disorders of Muscular and Skeletal System are the major topics discussed in this chapter.

Similarly, basic concepts of locomotion, types of muscles, muscular movement, components of the skeletal system; structure, location and functions, and disorders of the muscular and skeletal system such as gout, osteoporosis, arthritis and others can be learnt through in-depth learning of this chapter.

Diagrams, figures and activities make this chapter interesting and add fun to the learning experience. Which muscles perform voluntary activities and involuntary activities and why is understood through this chapter. What are bones? What is cartilage? What are joints? Types and location of different types of joints; these concepts are explained in a very comprehensive manner with the help of diagrams and examples in this chapter.

The topics and sub-topics in Chapter 20 Locomotion and Movement are given below.

• EX 20.1 – Types of Movement
• EX 20.2 – Muscle
• EX 20.2.1 – Structure of Contractile Proteins
• EX 20.2.2 – Mechanism of Muscle Contraction
• EX 20.3 – Skeletal System
• EX 20.4 – Joints
• EX 20.5 – Disorders of Muscular and Skeletal System.  

Access NCERT Solution For Class 11 Biology Chapter 20

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 fiber 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 fiber 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 fiber 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 fiber 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

b) Red and white muscles

c) Pectoral and Pelvic girdle

6. Match Column I with Column II:

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:

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

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 fiber Ca++ is stored in __________

(e) __________ and __________ pairs of ribs are called floating ribs.

(f) The human cranium is made of __________ bones

(a) Seven

(b) Fourteen

(c) Troponin, tropomyosin

(d) Sarcoplasmic reticulum

(e) Eleventh, twelfth

(f) Eight

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