Class 11 Biology

Chapter 17 Solutions — Locomotion and Movement

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Solutions

Overview

Step-by-step NCERT solutions for Locomotion and Movement (Chapter 17, NCERT Class 11 Biology) — every question and answer worked out in full, not just the final result. You can also read the Locomotion and Movement textbook chapter.

Solved

What these solutions cover

All 10 questions in Locomotion and Movement are solved in the PDF. Here's what's inside, exercise by exercise:

Exercises

Draw the diagram of a sarcomere of skeletal muscle showing different regions.
Define sliding filament theory of muscle contraction.
Describe the important steps in muscle contraction.
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.
5.
Write the difference between:
- (a) Actin and Myosin
- (b) Red and White muscles
- (c) Pectoral and Pelvic girdle
6.
Match Column I with Column II: Column I:
- (a) Smooth muscle
- (b) Tropomyosin
- (c) Red muscle
- (d) Skull Column II:
- (i) Myoglobin
- (ii) Thin filament
- (iii) Sutures
- (iv) Involuntary
What are the different types of movements exhibited by the cells of human body?
How do you distinguish between a skeletal muscle and a cardiac muscle?
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
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…

Sample

Worked examples

2 questions from Locomotion and Movement, solved step by step.

Exercises

Define sliding filament theory of muscle contraction.

The sliding filament theory states that muscle contraction occurs by the sliding of thin filaments (actin) over thick filaments (myosin), without any change in the length of either filament.

Key points of the theory:

- During contraction, actin thin filaments slide towards the centre of the A band (towards the M line)

- The Z lines, to which thin filaments are attached, are pulled inward, shortening the sarcomere

- The I bands get reduced (shorten) as actin slides in

- The H zone narrows as thin filaments cover more of the thick filaments

- The A band length remains constant throughout contraction

- Energy from ATP hydrolysis powers the cyclic formation and breaking of cross bridges between myosin heads and actin

Answer: The sliding filament theory states that muscle contraction occurs by the sliding of thin (actin) filaments over thick (myosin) filaments. During contraction, actin slides toward the M line, the I bands shorten, the H zone narrows, but the A band length remains unchanged.

Exercises

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

Cells of the human body exhibit three main types of movements:

1. Amoeboid movement:

- Exhibited by specialised cells such as macrophages and leucocytes (white blood cells) in blood

- Effected by pseudopodia formed by streaming of protoplasm (similar to Amoeba)

- Cytoskeletal elements like microfilaments are involved

2. Ciliary movement:

- Occurs in internal tubular organs lined by ciliated epithelium

- Coordinated beating of cilia in the trachea helps remove dust particles and foreign substances

- Ciliary movement also facilitates passage of ova through the female reproductive tract

3. Muscular movement:

- Required for movement of limbs, jaws, tongue, eyelids, etc.

- Made possible by the contractile property of muscle cells

- Used for locomotion and other body movements

Answer: Three types: (1) Amoeboid movement — by macrophages/leucocytes via pseudopodia and microfilaments; (2) Ciliary movement — by ciliated epithelium in trachea and female reproductive tract; (3) Muscular movement — by contractile muscle cells for locomotion and body movements.

All 10 questions in Locomotion and Movement are solved step by step in the Solutions PDF above.

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Chapter 17 Solutions — Locomotion and Movement

Overview

What these solutions cover

Exercises

Worked examples

Define sliding filament theory of muscle contraction.

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

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