Exercise Solutions Available
Step-by-step answers for all textbook questions in this chapter
I. Choose the Best Answer (MCQs)
Q1. Which body parts help in movement? (i) Bones (ii) Skin (iii) Muscles (iv) Organs
- (a) (i) and (iii) (b) (ii) and (iv) (c) (i) and (ii) (d) (iii) and (iv)
Q2. Which organism lacks muscles and skeleton for movement?
- (a) Snail (b) Hydra (c) Earthworm (d) Fish
Q3. Which joints are immovable?
- (a) Shoulder and hip (b) Knee and elbow (c) Upper jaw and skull (d) Wrist and ankle
Q4. Why do underwater divers wear fin-like flippers?
- (a) To swim easily in water (b) To look like a fish (c) To walk on water surface (d) To avoid sharks
Q5. External ear (pinna) is supported by:
- (a) Bone (b) Cartilage (c) Tendon (d) Muscle
Q6. Cockroach moves with the help of its:
- (a) Wings (b) Paddles (c) Fins (d) Whole body
Q7. Which vertebrae category is correctly numbered?
- (a) Cervical - 7 (b) Thoracic - 5 (c) Lumbar - 12 (d) Sacral - 4
Additional MCQs
Q8. Greatest range of movement is seen in which joint?
- (a) Hinge (b) Pivot (c) Ball and socket (d) Gliding
Q9. The strongest bone of the human skeleton:
- (a) Femur (b) Humerus (c) Tibia (d) Skull
Q10. Phalanges refer to bones of:
- (a) Skull (b) Toes/fingers (c) Spine (d) Ribs
II. Fill in the Blanks
1. Movement of organisms from place to place is called locomotion. 2. Movement refers to change in position of a body part. 3. A structure providing rigid framework is called a skeleton. 4. Axial skeleton consists of skull, facial bones, sternum, ribs, and vertebral column. 5. Appendicular skeleton consists of pelvic and pectoral girdles (and limb bones). 6. The place where two bones meet is a joint. 7. Smooth muscle is attached to blood vessels, iris, bronchi, and skin. 8. Radial muscle makes the pupil wider. 9. Cockroach exoskeleton is made of chitin. 10. Setae are seen in earthworms. 11. Atlas/Axis joint is a pivot joint. 12. Bone-to-bone connection = ligament. 13. Bone-to-muscle connection = tendon. 14. Inflammation of joints leads to arthritis. 15. The smallest/lightest bone = Stapes (in the middle ear). 16. The cranium protects the brain.
III. True or False
IV. Match the Following
Match 1 — Bones and Regions:
| Bone | Region | Answer |
|---|---|---|
| Humerus | (a) Forearm | (c) Upper arm |
| Radius | (b) Leg | (a) Forearm |
| Tarsals | (c) Upper arm | (b) Leg |
| Atlas | (d) Vertebral column | (d) Vertebral column |
Match 2 — Joint Types and Examples:
| Joint Type | Example | Answer |
|---|---|---|
| Ball and socket | (a) Elbow | (d) Hip |
| Saddle | (b) Spine | (c) Thumb |
| Hinge | (c) Thumb | (a) Elbow |
| Gliding | (d) Hip | (b) Spine |
Match 3 — Organisms and Locomotion:
| Organism | Locomotion Type | Answer |
|---|---|---|
| Earthworm | (a) Flapping | (b) Setae |
| Cockroach | (b) Setae | (d) Legs |
| Birds | (c) Slithering | (a) Flapping |
| Snake | (d) Legs | (c) Slithering |
V. Very Short Answers
Q1. Define locomotion. Answer: The movement of an organism from one place to another.
Q2. How does a fish change direction? Answer: The caudal/tail fin helps the fish steer and change direction while swimming.
Q3. Name types of flight in birds. Answer: Gliding and flapping.
Q4. Why do birds have hollow bones? Answer: Hollow bones contain air spaces, reducing body weight and aiding flight.
Q5. Name types of movement seen in animals. Answer: 1. Amoeboid movement 2. Ciliary movement 3. Muscular movement
Q6. Name two joints with examples. Answer: 1. Ball and socket — Hip 2. Hinge — Elbow
Q7. Name the types of muscles. Answer: 1. Striated (skeletal/voluntary) 2. Non-striated (smooth/involuntary) 3. Cardiac muscle
Q8. Name vertebral column regions with vertebrae counts. Answer: Cervical (7), Thoracic (12), Lumbar (5), Sacral (5 fused), Coccygeal (4 fused).
VI. Short Answers
Q1. What is a skeleton? Answer: The skeletal system provides rigid framework supporting and protecting the body. It is composed of connective tissues including bones, cartilage, tendons, and ligaments.
Q2. What is the cranium? Answer: Eight bones fuse together to form the cranium, also called the "brain box" because it protects the brain.
Q3. Why is the backbone slightly movable? Answer: Vertebrae in the backbone are joined by gliding points, permitting bending forward, backward, and sideways — but not free movement.
Q4. Differentiate axial and appendicular skeleton.
| Feature | Axial Skeleton | Appendicular Skeleton |
|---|---|---|
| Location | Along body's central axis | Appendages and girdles |
| Components | Skull, facial bones, sternum, ribs, vertebral column | Shoulder girdle, pelvic girdle, limb bones, wrist, ankle, hand, foot bones |
| Function | Protects internal organs | Enables movement |
Q5. What is a ligament? Answer: A band of strong fibrous tissue connecting one bone to another bone at a joint.
Q6. Define muscle. Answer: Muscles are long bundles of contractile tissue with a fixed end (origin) and a movable end that pulls on other body parts.
Q7. Differentiate tendons and ligaments.
| Feature | Tendons | Ligaments |
|---|---|---|
| Connects | Muscle to bone | Bone to bone |
| Made of | Elastic tissue | Tough fibrous tissue |
| Function | Transmit muscle force | Stabilize joints |
Q8. How are joints classified? Answer: Three types based on movement: 1. Fixed/Immovable — e.g., skull sutures 2. Slightly movable — e.g., rib-to-breastbone, vertebrae 3. Freely movable — six subtypes: ball & socket, hinge, pivot, condyloid, gliding, saddle
Q9. What is a synovial joint? Answer: A freely movable joint where two bones connect via a cartilage-lined cavity filled with synovial fluid. The fluid lubricates the joint. These are the most flexible joints with four structural features: articular cartilage, synovial membrane, synovial fluid, and joint capsule.
Q10. Explain the arrangement of arm bones. Answer: The upper limb includes humerus (upper arm), radius and ulna (forearm), carpals (wrist), metacarpals (palm), and phalanges (fingers). Hinge joints connect these, allowing movement in one direction.
VII. Detailed Answers
Q1. Differentiate: (i) Movement vs Locomotion, (ii) Endoskeleton vs Exoskeleton, (iii) Pectoral vs Pelvic girdle, (iv) Ball & Socket vs Hinge Joint, (v) Voluntary vs Involuntary Muscle
(i) Movement vs Locomotion:
| Feature | Movement | Locomotion |
|---|---|---|
| Definition | Change in position of body parts | Organism moves from one place to another |
| Nature | Can be voluntary or involuntary | Always voluntary |
| Level | Occurs at biological/cellular level | Occurs at organism level |
(ii) Endoskeleton vs Exoskeleton:
| Feature | Endoskeleton | Exoskeleton |
|---|---|---|
| Location | Inside the body | Exterior surface of the body |
| Origin | Mesoderm | Ectoderm or mesoderm |
| Example | Human beings | Fish scales, insect exoskeleton |
(iii) Pectoral vs Pelvic girdle:
| Feature | Pectoral girdle | Pelvic girdle |
|---|---|---|
| Location | Shoulder region | Hip region |
| Articulates with | Forelimbs | Hind limbs |
| Structure | Shoulder blade and collar bone remain separate | Three bones fuse into single hip bone |
| Strength | Comparatively lighter | Strong, bears significant stress |
(iv) Ball & Socket vs Hinge Joint:
| Feature | Ball & Socket | Hinge |
|---|---|---|
| Structure | Ball-shaped head fits into cup-like socket | Cylindrical protrusion fits into trough-shaped depression |
| Movement | Three planes; greatest range | One plane; bending and straightening only |
| Examples | Shoulder, Hip | Elbow, Knee, Ankle |
(v) Voluntary vs Involuntary Muscle:
| Feature | Voluntary | Involuntary |
|---|---|---|
| Appearance | Striated, multinucleate, unbranched | Non-striated, single nucleus |
| Attachment | Attached to bones | Attached to soft parts (blood vessels, iris, skin) |
| Control | Under conscious control | Not under conscious control |
| Example | Muscles of arms and legs | Smooth muscles in internal organs |
Q2. What are antagonistic muscles? Give an example. Answer: Muscles that work in opposing pairs. The biceps and triceps in the upper arm are an example:
- When the biceps contracts, the lower arm raises (arm bends), while the triceps relaxes.
- When the triceps contracts, the arm straightens, while the biceps relaxes.
Q3. How is a bird's skeleton suited for flying? Answer: 1. Birds have streamlined bodies with light, strong, hollow bones containing air spaces. 2. Hind limbs are modified into claws for walking and perching. 3. Breast bones are enlarged to anchor massive flight muscles. 4. Forelimbs are modified as wings with special flight muscles. 5. Wings and tail have long feathers aiding flight.
Q4. Functions of the human skeleton. Answer: 1. Provides structure and shape to the body. 2. Supports and protects internal organs. 3. Stores calcium and phosphorus needed for regulatory functions. 4. Produces red blood cells in bone marrow. 5. Bones act as levers for muscular action.
Q5. Types of joints with examples.
| Joint Type | Movement | Example |
|---|---|---|
| Ball and Socket | All directions | Shoulder, Hip |
| Hinge | One direction | Elbow, Knee, Ankle |
| Pivot | Rotation | Atlas/Axis (top of spine) |
| Condyloid | Two directions | Wrist |
| Gliding | Sliding | Between vertebrae |
| Saddle | Two directions | Thumb |
Q6. Human axial skeleton.
Skull: 22 bones total — 8 form the cranium (protecting brain), 14 form the face. The lower jaw is the only movable skull bone.
Vertebral column: 33 vertebrae — 7 cervical, 12 thoracic, 5 lumbar, 5 fused sacral, 4 fused coccygeal. It protects the spinal cord, supports the head, and aids in posture.
Sternum/Ribcage: 12 pairs of ribs. First 10 pairs attach to the breastbone; last 2 pairs are free-floating. Protects lungs, heart, and part of the liver.
Q7. Types of movements in living organisms. 1. Amoeboid movement — Pseudopodia (false feet) move with protoplasmic flow, seen in Amoeba and white blood cells. 2. Ciliary movement — Hair-like cilia on epithelial cells create coordinated movement, seen in Paramecium and respiratory tract. 3. Muscular movement — Most complex type, brought about by the musculoskeletal system (joints + skeleton + muscles). Seen in higher vertebrates including humans.
Common Mistakes
- Saying bones move on their own without muscles: Bones cannot move by themselves; muscles contract and pull on bones at joints.
- Confusing tendons with ligaments: Tendons connect muscle to bone; ligaments connect bone to bone.
- Confusing axial and appendicular skeleton: Axial is along the midline (skull, spine, ribs); appendicular includes limbs and girdles.
- Saying cardiac muscle is voluntary: Cardiac muscle is involuntary — we cannot consciously control heartbeats.
- Mixing up joint types: Hinge joints move in one plane; ball-and-socket joints move in all directions.
- Forgetting that pelvic girdle is appendicular: The pelvic girdle belongs to the appendicular skeleton, not axial.
Exam Checklist
- [ ] Can you distinguish between movement and locomotion?
- [ ] Can you list and describe the three types of muscles?
- [ ] Can you differentiate between tendons and ligaments?
- [ ] Can you list the bones of the axial and appendicular skeleton?
- [ ] Can you name and give examples of 6 types of joints?
- [ ] Can you explain antagonistic muscles with the biceps-triceps example?
- [ ] Can you describe how a bird's skeleton is adapted for flight?
- [ ] Can you explain the three types of movement (amoeboid, ciliary, muscular)?
- [ ] Can you describe the vertebral column with correct vertebrae counts?
- [ ] Can you explain synovial joints and their features?