SCIENCE CH- 8 BODY MOVEMENTS(NOTEBOOK AND WORKBOOK EXERCISE)
BODY MOVEMENTS(NOTEBOOK EXERCISE)
NEW WORDS
1. cerci
2.antennae
3.cartilage
4.exoskeleton
5.streamlined
NEW TERMS
1. gliding- joint formed between bones that meet at flat or nearly flat articular surfaces.
2.exoskeleton: external skeleton found in insects and snails
ANSWER IN BRIEF
a. Name the parts of the human skeleton.
ANS. The main parts of the human skeleton, namely, the skull, the spine or the backbone, the rib cage, the limbs, the shoulder bones and the pelvic bones.
b. Explain the importance of a swim bladder in a fish.
ANS. Most fish have a special structure called swim bladder that can be filled with air or emptied to help them move up and down in water.
c. Name the different features of the body of a bird that help in flying.
ANS. The following features help the birds to fly;
1. The bodies of birds are streamlined, which reduces the resistance of air while flying.
2. Birds have light and hollow bones.
3. The forelimbs in birds are modified into wings.
4. The wings are covered with feathers which help in flying.
5. Birds have strong shoulder bones and chest muscles to support the movement of wings during flight.
d. Explain the role of muscles in movement of bones.
ANS. In order to move a bone, we need the help of muscles. A muscle is made up of fibres which can shorten or lengthen. The shortening of muscle fibres is known as contraction and the lengthening of muscle fibres is known as relaxation. One end of a muscle is attached to a movable bone and another is attached to a fixed bone. When a muscle contracts, the movable bone is pulled with the muscle. Muscles always work in pairs.
e. Differentiate between a vertebrate and an invertebrate.
ANS. Animals having a backbone are known as vertebrates ,A few examples of vertebrate animals are fish, snakes, birds and men
Animals without a backbone are known as invertebrates., A few examples of invertebrate animals are earthworms, snails and insects such as a cockroach.
DEFINE:
a. Backbone- Long bony structure that runs down the centre of your back, from the base of the skull to the lower back is known as the backbone.
b. Movement and locomotion - The act of moving from one place to another is known as locomotion. Animals also perform many movements without shifting from one place such as shutting eyelids, chewing, sitting up and lying down.
c. Gliding Joint - A type of joint where flat bones glide over each other to permit movements is known as a gliding joint. The joints between the bones of the ankle are also gliding joints.
d. Fixed Joint - Joints hold your bones together and allow your rigid skeleton to move. Fixed joints. Some of your joints, like those in your skull, are fixed and don't allow any movement.
Answer the following questions in detail.
a. What are the different types of joints present in the human body?
ANS. Types of Joints
Immovable or fixed joints -- Example: joints between skull bones
Slightly movable joints-- Example: joints between vertebrae
Freely movable joints-- Hinge joints Example: knee joint, elbow joint
Ball and socket joints Example: shoulder joint, hip joint
Pivot joints Example: joint between the skull and the spine
Gliding joints Example: joints between the wrist bones
b. How does a snail move?
ANS. The foot produces wave-like movements which propels the body of the snail forwards.
The foot secretes a slimy substance called mucous.
The snail moves on this layer of mucous, thus avoiding friction.
The snail leaves a trail of mucous behind as it moves.
With its muscular foot and mucus, the snail can easily glide over smooth or rough surfaces on which it can move vertically and even upside-down.
A snail can even move over a sharp razor blade without getting cut, thanks to the protective and slimy mucous.
c. What is X-ray imaging? What are the uses of an X-ray image?
ANS. X-rays are radiations which can pass through the skin and soft tissues. However X-rays cannot penetrate the bones. Hence, we can see the bones clearly in an X-ray image.
X-ray images can be used to study bones and find out if a bone is fractured or not.
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