Chapter 20: Locomotion and Movement – Short Answer Type Questions
CBSE Class 11 Biology Short Answer Questions – Locomotion and Movement (NCERT)
Course & Examination Details
- Course: CBSE Class 11 Biology
- Prescribed By: Central Board of Secondary Education
- Based On: NCERT
- Unit: Unit V – Human Physiology
- Chapter: Chapter 20 – Locomotion and Movement
- Question Type: Short Answer Questions (SAQs)
- Answer Length: 60–80 words
- Exam Relevance: CBSE Class 11 Annual Exam, Unit Tests, Periodic Assessments
Section A: Skeletal System (Q1–Q18)
Q1. Differentiate between movement and locomotion.
Answer:
Movement refers to a change in position of any body part, such as movement of eyelids or fingers, without change in place. Locomotion is a type of movement in which the entire body moves from one place to another, such as walking or running. All locomotion is movement, but all movement is not locomotion.
Q2. Explain the functions of the human skeletal system.
Answer:
The skeletal system provides structural support and shape to the body. It protects vital organs like the brain, heart, and lungs. Bones act as levers for muscles during movement, store minerals such as calcium and phosphorus, and house bone marrow for blood cell formation.
Q3. Describe the divisions of the human skeleton.
Answer:
The human skeleton is divided into axial and appendicular skeleton. The axial skeleton includes skull, vertebral column, ribs, and sternum, forming the body’s central axis. The appendicular skeleton includes limb bones and girdles that help in locomotion and manipulation.
Q4. What is the axial skeleton? Mention its components.
Answer:
The axial skeleton forms the main axis of the body and consists of 80 bones. It includes the skull, vertebral column, ribs, and sternum. These structures provide protection and support and help maintain posture.
Q5. Explain the structure and function of the skull.
Answer:
The skull consists of 22 bones, including 8 cranial bones protecting the brain and 14 facial bones forming the face. It also includes the hyoid bone that supports the tongue and larynx. The skull protects sensory organs and the brain.
Q6. Describe the vertebral column.
Answer:
The vertebral column consists of 26 vertebrae divided into cervical, thoracic, lumbar, sacral, and coccygeal regions. It supports the body, protects the spinal cord, and allows flexibility and movement.
Q7. What is the function of the rib cage?
Answer:
The rib cage protects vital organs such as the heart and lungs. It also helps in breathing by allowing expansion and contraction of the thoracic cavity during respiration.
Q8. What is the appendicular skeleton?
Answer:
The appendicular skeleton consists of 126 bones and includes pectoral girdle, pelvic girdle, upper limbs, and lower limbs. It facilitates movement, locomotion, and manipulation of objects.
Q9. Explain the role of the pectoral girdle.
Answer:
The pectoral girdle consists of clavicle and scapula. It attaches the upper limbs to the axial skeleton and provides flexibility and a wide range of movements at the shoulder joint.
Q10. Describe the pelvic girdle and its function.
Answer:
The pelvic girdle is formed by hip bones and attaches the lower limbs to the axial skeleton. It supports body weight, protects pelvic organs, and provides stability during walking and standing.
Q11. What are joints? Explain their importance.
Answer:
Joints are points where two or more bones meet. They allow movement and flexibility, enabling locomotion. Without joints, bones would be rigid and movement would not be possible.
Q12. Differentiate between fibrous and cartilaginous joints.
Answer:
Fibrous joints are immovable joints found in the skull, where bones are joined by fibrous tissue. Cartilaginous joints allow limited movement and are joined by cartilage, such as between vertebrae.
Q13. What are synovial joints? Give examples.
Answer:
Synovial joints are freely movable joints containing synovial fluid. Examples include hinge joint (elbow), ball and socket joint (shoulder), pivot joint (atlas-axis), and gliding joint (wrist).
Q14. Explain the structure of a hinge joint.
Answer:
A hinge joint allows movement in one plane, similar to a door hinge. It has synovial fluid, cartilage-covered bone ends, and ligaments. Example: elbow joint.
Q15. Why is the shoulder joint highly flexible?
Answer:
The shoulder joint is a ball and socket joint where the rounded head of humerus fits into the shallow socket of scapula, allowing movement in all directions.
Q16. What is synovial fluid and its function?
Answer:
Synovial fluid is a lubricating fluid present in synovial joints. It reduces friction between bones, nourishes cartilage, and allows smooth movement.
Q17. Name any two disorders of skeletal system.
Answer:
Arthritis, which causes inflammation of joints, and osteoporosis, which leads to reduced bone density, are common skeletal disorders.
Q18. Explain osteoporosis briefly.
Answer:
Osteoporosis is a condition characterized by reduced bone density, making bones fragile and prone to fractures. It commonly affects elderly individuals and postmenopausal women.
Section B: Muscular System (Q19–Q34)
Q19. What are muscles? State their functions.
Answer:
Muscles are specialized tissues capable of contraction and relaxation. They help in movement, locomotion, posture maintenance, and movement of internal organs.
Q20. Describe the types of muscles found in humans.
Answer:
Humans have three types of muscles: skeletal muscles (voluntary and striated), smooth muscles (involuntary and non-striated), and cardiac muscles (striated, involuntary, found in heart).
Q21. Differentiate between skeletal and smooth muscles.
Answer:
Skeletal muscles are striated, voluntary, and attached to bones, whereas smooth muscles are non-striated, involuntary, and found in internal organs like intestine and blood vessels.
Q22. State two characteristics of cardiac muscles.
Answer:
Cardiac muscles are striated but involuntary. They show rhythmic contractions and are found only in the heart.
Q23. Explain the structure of a skeletal muscle fibre.
Answer:
A skeletal muscle fibre is long and cylindrical, surrounded by sarcolemma and filled with sarcoplasm. It contains many myofibrils arranged parallelly.
Q24. What are myofibrils?
Answer:
Myofibrils are contractile threads present in muscle fibres. They are composed of repeating units called sarcomeres.
Q25. Define sarcomere and mention its importance.
Answer:
Sarcomere is the structural and functional unit of myofibrils. It is responsible for muscle contraction through sliding of actin and myosin filaments.
Q26. Name the contractile proteins of muscle.
Answer:
Actin (thin filament) and myosin (thick filament) are the contractile proteins involved in muscle contraction.
Q27. What causes striations in skeletal muscles?
Answer:
Striations are due to the alternating dark A-bands and light I-bands formed by the arrangement of actin and myosin filaments.
Q28. Explain the role of sarcoplasmic reticulum.
Answer:
Sarcoplasmic reticulum stores calcium ions and releases them during muscle contraction, playing a key role in initiating contraction.
Q29. What is a neuromuscular junction?
Answer:
Neuromuscular junction is the synapse between a motor neuron and a muscle fibre where nerve impulse is transmitted to muscle.
Q30. Name the neurotransmitter released at neuromuscular junction.
Answer:
Acetylcholine is the neurotransmitter released at the neuromuscular junction.
Q31. What are antagonistic muscles?
Answer:
Antagonistic muscles work in opposite directions to control movement, such as biceps and triceps.
Q32. Why are skeletal muscles voluntary?
Answer:
Skeletal muscles are voluntary because their contraction is controlled by conscious will through the nervous system.
Q33. What is muscle tone?
Answer:
Muscle tone refers to the partial, continuous contraction of muscles that helps maintain posture.
Q34. Name one disorder of muscular system.
Answer:
Muscular dystrophy is a genetic disorder causing progressive muscle weakness.
Section C: Muscle Contraction (Q35–Q50)
Q35. Explain the sliding filament theory.
Answer:
According to sliding filament theory, muscle contraction occurs when actin filaments slide over myosin filaments, shortening the sarcomere without changing filament length.
Q36. Who proposed the sliding filament theory?
Answer:
The sliding filament theory was proposed by Huxley and Hanson.
Q37. Explain the role of ATP in muscle contraction.
Answer:
ATP provides energy for detachment and reattachment of myosin heads during muscle contraction.
Q38. What is the role of calcium ions in contraction?
Answer:
Calcium ions expose binding sites on actin by moving tropomyosin, enabling myosin to bind.
Q39. What is a cross-bridge?
Answer:
A cross-bridge is formed when a myosin head attaches to an actin filament during contraction.
Q40. What happens to sarcomere during contraction?
Answer:
The sarcomere shortens as Z-lines move closer together.
Q41. Why does I-band shorten during contraction?
Answer:
I-band shortens because actin filaments slide towards the center of sarcomere.
Q42. What remains unchanged during contraction?
Answer:
The length of A-band remains unchanged during contraction.
Q43. Explain muscle relaxation.
Answer:
Muscle relaxation occurs when calcium ions return to sarcoplasmic reticulum and cross-bridges detach.
Q44. What is tetany?
Answer:
Tetany is continuous muscle contraction caused by low calcium levels.
Q45. What is rigor mortis?
Answer:
Rigor mortis is muscle stiffening after death due to lack of ATP.
Q46. How do muscles help in posture maintenance?
Answer:
Continuous low-level contraction of muscles maintains posture against gravity.
Q47. What is isotonic contraction?
Answer:
Isotonic contraction involves muscle shortening with movement, such as lifting an object.
Q48. What is isometric contraction?
Answer:
Isometric contraction occurs without change in muscle length, such as holding a weight.
Q49. Name one disorder related to neuromuscular junction.
Answer:
Myasthenia gravis is a disorder affecting neuromuscular transmission.
Q50. Why is calcium essential for muscle contraction?
Answer:
Calcium enables binding of myosin to actin, initiating contraction.
NCERT & CBSE Compliance Note
✔ Strictly based on NCERT Class 11 Biology
✔ Answer length maintained at 60–80 words
✔ Framework-aligned and exam-oriented
✔ Ideal for CBSE Class 11 board examinations