Bones and Joints: NCERT solution
Fill in the blanks:
- Joints of the bones help in the ---------of the body.
Answer: Movement - A combination of bones and cartilages forms the -------- of the body.
Answer: Skeleton - The bones at the elbow are joined by a -------- joint.
Answer: Hinge joint - The contraction of the -------- pulls the bones during movements.
Answer: Muscles
Answer the following questions:
Indicate true and false among the following sentences:
- The movement and locomotion of all animals is exactly the same.
- The cartilages are harder than bones.
- The finger bones do not have joints.
- The fore arm has two bones.
- Cockroaches have an outer skeleton.
Answer: 1 False, 2 False, 3 False, 4 True, 5 True
Match the items in column I with items of column II
| Column I | Column II |
|---|---|
| (a) Upper jaw | (1) Have fins on the body |
| (b) Fish | (2) Has outer skeleton |
| (c) Ribs | (3) Is an immovable joint |
| (d) Snail | (4) Protect the heart |
| (e) Cockroach | (5) Shows very slow movement |
Answer: (a) 3 (b) 1 (c) 4 (d) 5 (e) 2
Answer the following questions:
Question 1: What is a ball and socket joint?
Answer: In this joint the rounded end of one bone fits into the cavity (hollow space) of another bone. It permits movement in all directions.
Question 2: Which of the skull bones are movable?
Answer: Lower jaw bone or mandible is the only movable bone in the skull.
Question 3: Why can our elbow not move backwards?
Answer: Elbow joint is composed of hinge joint. These joints allow movement in one plane and up to 180° only. Hence, we cannot move our elbows backwards.
Extra Questions
Question 1: What are the main functions of the skeleton system?
Asnwer: Functions of the skeletal system are as follows:
- It gives shape and provides supports to the body.
- It forms the framework of the body.
- It protects some internal organs.
Question 2: Name the various organs of the skeletal system.
Asnwer: Various organs of the skeletal system are: skull, vertebral column, rib cage, bones in arms and legs, shoulder bone and hip bone.
Question 3: Give an example of pivot joint in the human body.
Asnwer: The joint between skull and first vertebra
Question 4: What is slithering movement?
Asnwer: Movement of a snake is called slithering movement.
Question 5: How many vertebrae are found in the human backbone?
Asnwer: There are 33 vertebrae in the human backbone.
Question 6: How many ribs are found in the rib-cage of humans?
Asnwer: There are 12 pairs of ribs in the rib-cage of humans.
Question 7: How does a snake move?
Asnwer: A snakes moves by making loops on its sides.
Question 8: How does a fish swim in water?
Asnwer: When a fish swims; its front part curves to one side and the tail part stays in the opposite direction. In the next move, the front part curves to the opposite side and the tail part also changes its position to another side. The tail fin helps in changing direction.
Question 9: How does the snail move?
Asnwer: A snail moves using its muscular foot.
Question 10: How many bones are found in the human skeleton system?
Asnwer: There are 206 bones in the human skeleton.