Biology

Class 12 Biology Chapter 16 Locomotion and Movement

NIOS Biology Intext Solutions Chapter 16

INTEXT QUESTIONS 16.1

1. What would you call the following as – movement (M) or locomotion (L) ?

  • The elephant uses its trunks to pick up sticks ( )
  • The cow uses its tail to drive away flies ( )
  • A mouse runs into a hole. ( )
  • The bees leave their hive in search of pollen ( )
  • Johan kicks the football into the goal ( )
  • The cat jumps on to the window ( )

Ans: M, M, L, L, M, L

INTEXT QUESTIONS 16.2

1. State the similarity in internal structure between a cilium and a flagellum as learnt in lesson 4 of your text book?

Ans: Both cilia and flagella are made of microtubules arranged in a similar manner.

2. What is an effective stroke ? Which stroke is called the recovery stroke as depicted during ciliary movement ?

Ans: 

  • Ciliary beat begins with fast stroke ahead in one direction called effective stroke
  • The second stroke by which it bends back and returns to its original position is called the recovery stroke.

3. State the difference between flagella and cilia with regard to location and number.

Ans: 

  • Location – cilia all over body, flagella at anterior or posterior end
  • Number – cilia many, flagella 1 or 2

INTEXT QUESTION 16.3

1. Name the structure that connects 

(i) a bone to another bone 

(ii) muscle to bone. 

Which type of tissue are these ?

Ans: 

(i) Ligament

(ii) Tendon

Both ligament and tendon are connective tissues. 

2. Why is the muscle cell also called muscle fibre ?

Ans: 

The muscle cell, also called muscle fibre because of its long shape. 

3. Why is the mechanism of muscle contraction called ‘sliding movement’?

Ans: 

Striated muscle contraction is explained by Sliding Filament Theory. This theory can be explained through the following steps:

  • (i) The thick and thin filaments myosin and actin are linked by crossbridges of troponin and tropomyosin.
  • (ii) These crossbridges, on contraction, pull the thin filaments back over thick filaments.
  • (iii) As a result, the thin filaments slide over the thick filaments. Calcium and ATP are required for attaching and releasing Troponin.
  • (iv) Because of this sliding action, Z lines come closer and the sarcomere shortens.
  • (v) All sarcomeres shorten together so the entire muscle contracts.
  • (vi) The muscle relaxes when crossbridges relax and sarcomere regains original position.

4. What is the chemical composition of myofilaments.

Ans: 

Myofilaments are proteins which are of two types:

  • (i) thick filaments made of myosin protein
  • (ii) thin filaments made of actin protein.

5. In a muscle, where can you find the following? myofilaments, muscle fibres.

Ans: 

  • myofilaments in muscle fibre
  • muscle fibres in muscle tissue

INTEXT QUESTION 16.4

1. Name an animal with endoskeleton and one with exoskeleton.

Ans: Endoskeleton- humans

Exoskeleton- Molluscs

2. Name main parts of skeleton and mention their functions.

Ans: 

The main parts of the human skeleton are the axial and appendicular skeletons. 

  • The axial skeleton protects the skull, jaws and spinal column.
  • The appendicular skeleton protects the internal organs such as the pectoral, pelvic, arms and legs.
  • They also help in locomotion and movement.
  • The bone marrow manufactures blood cells and also gives shape to body.

3. Name any two disorders of the musculo–skeletal system which are hereditary.

Ans: 

  • Myasthenia gravis is caused by a gene on the X chromosome and so is hereditary. The muscles slowly waste away, and the patient gradually becomes immobile, and in the last stages, even the jaw muscles do not work, and the patient is unable to eat.
  • Muscular dystrophy is an autosomal dominant disorder. In this hereditary disorder, muscles waste away and person becomes immobile.

4. What causes osteoporesis and gout ? 

Ans: 

  • Osteoporosis is the softening of bones due to calcium deficiency.
  • Gout results in painful inflammation of joints due to elevated level of uric acid in blood.

5. Which limbs are supported by which girdles and which kind of muscles are attached to the limb skeleton ?

Ans: 

  • Pectoral – fore limbs
  • Pelvic – hind limb
  • Striped or striated

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