NIOS Class 12 Biology Locomotion and Movement explains how living organisms move using bones, muscles, and joints. It highlights types of movements, muscle contraction, and skeletal systems. Students also study examples of locomotion in animals.
Solved terminal exercises provide easy answers for practice. This chapter is crucial in understanding how the body functions in movement and survival, making it an important part of the NIOS Class 12 Biology exam preparation.
NIOS Class 12 Biology Locomotion and Movement Solutions
1. Distinguish between the following pairs of terms:
- (i) Movement and Locomotion
- (ii) Thick and Thin myofilaments
- (iii) Tendon and Ligament
- (iv) Cilia and Flagella
- (v) Tropic and Nastic movement
(i) Movement and Locomotion
Movement is the temporary or permanent displacement of a body or its parts from its original position. Locomotion, on the other hand, is the displacement of the entire body from one place to another.
(ii) Thick and Thin myofilaments
Thick filaments are made of myosin protein, and thin filaments are made of actin protein.
(iii) Tendon and Ligament
The ends of muscles connect to bones through another kind of connective tissue called a tendon. Ligaments connect bones.
(iv) Cilia and Flagella
Cilia are minute hair-like processes that are motile and extend from cell surfaces. Flagella are long, whip-like structures mostly present singly or in a small number at one end of a cell.
(v) Tropic and Nastic movement
Movement of plants in response to external stimuli is called tropic movements. Nastic movement is also a response of a plant to a stimulus, but it does not move in the same direction as the stimulus.Â
2. Enlist the steps in muscle contraction as explained by the sliding filament theory.
Striated muscle contraction is explained by the Sliding Filament Theory. This theory can be explained through the following steps:
- (i) The thick and thin filaments of 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 the crossbridges relax and the sarcomere regains its original position.
3. How does Paramecium swim in water?
Paramecium has cilia all around its body. Ciliary beat begins with a fast stroke ahead in one direction called the effective stroke, and then it bends back and returns to its original position. This second stroke is called the recovery stroke. During the ciliary beat, water is propelled parallel to the ciliated surface.
4. Answer in one word or sentence
(i) What is the shape of the actin molecule?
(ii) What is the chemical nature of troponin and tropomyosin?
(iii) What is meant by the recovery stroke of cilia?
(iv) Give an example of each of geotropism and phototropism.
(v) Why do we say that vertebrate muscle contraction is energy-dependent?
- (i) The actin molecule is globular in shape.
- (ii) Both troponin and tropomyosin are proteins.
- (iii) Recovery stroke of cilia means to return to the original position after bending.
- (iv) Roots growing downwards are geotropism, and shoots growing upwards are phototropism.
- (v) Vertebrate muscle contraction is energy-dependent because it requires ATP to contract.
