Textbook Questions and Answers
Keywords:
- Sternum: A long, flat bone that the ribs are connected to.
- Girdle: A bony structure that provides support and attachment for limbs.
- Fibrous: Consisting of fibers.
- Tendons: A strong, flexible band of tissue that connects a muscle to a bone.
- Contract: To become shorter or tighter.
- Relax: To lengthen and become loose.
- Membrane: A thin, sheet-like structure.
- Posture: The way a person sits, stands, walks, and so on.
Q.1) Assertion and Reasoning Questions
1) Assertion (A): The vertebral column protects the spinal cord.
Reason (R): The spinal cord passes through the vertebral column.
Ans: (a) Both A and R are true, and R is the correct explanation of A.
2) Assertion (A): We should wash our eyes with clean water regularly.
Reason (R): Washing the eyes helps us feel fresh.
Ans: (b) Both A and R are true, but R is not the correct explanation of A.
Answer the Following Questions:
1. Why does the skull have immovable joints, but the neck has a movable joint?
Ans: The skull has immovable joints to protect the brain from injury. The neck has a pivot joint so that we can move our head in different directions.
2. Why is it dangerous to have poor posture while sitting or carrying a heavy school bag?
Ans: Poor posture puts extra pressure on the spine and muscles, causing back pain, shoulder pain, and tiredness.
3. Ravi touched a hot pan and immediately pulled his hand away before anyone told him to do so. Which part of the nervous system helped him? Why?
Ans: The spinal cord helped him. It controls reflex actions, which are quick, automatic responses to protect the body.
Q.4) Write the difference between voluntary and involuntary muscles.
| Voluntary Muscle | Involuntary Muscle |
| 1) The movement of these muscles is under our control. | 1) The movement of these muscles is not under our control. |
| 2) Eg: Muscles of the hands and legs. | 2) Eg: Muscles of the lungs, kidneys, etc. |
Q.6) How many types of nerves are there? Explain each type with its function.
Ans: There are three types of nerves:
- Sensory nerves: Carry messages from the sense organs to the spinal cord and brain.
- Motor nerves: Carry messages from the brain to the other parts of the body.
- Mixed nerves: They can carry messages to and from the brain.
Q.7) Name the three parts of the brain and explain their functions.
Ans: The brain has three main parts:
1) Cerebrum:
- i) It is the largest part of the brain.
- ii) It controls our memory, thoughts, intelligence, learning, and voluntary muscles.
2) Cerebellum:
- i) It is located below the cerebrum.
- ii) It controls the movement of muscles.
3) Medulla Oblongata:
- i) It connects the lower part of the brain to the spinal cord.
- ii) It regulates our involuntary muscles.
Q.9) Explain the different types of joints in the human body with one example of each.
Ans:
(1) Pivot joint:
- i) It is found between the skull and the top vertebra.
- ii) It allows us to move our head up, down, and sideways.
(2) Ball and socket joint:
- i) These allow movement in all directions. (e.g., shoulder and hip joints)
(3) Hinge joint:
- i) These are found in the knees, elbows, fingers, and toes.
- ii) These allow movement in only forward and backward directions.
(4) Gliding joint:
- i) These are found in the wrists and the ankles.
- ii) Bones slide over each other.
(5) Fixed joint:
- i) Does not allow movement in bones; they are joined tightly together.
- ii) Eg: Skull bones (except the lower jaw).