Chapter 20: Locomotion and Movement – Long Answer Type Questions
CBSE Class 11 Biology Long 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: Long Answer Questions (LAQs)
- Answer Length: 120–150 words
- Exam Relevance: CBSE Class 11 Annual Examination, Unit Tests, School Assessments
Section A: Skeletal System (Q1–Q9)
Q1. Explain the difference between movement and locomotion with examples.
Answer:
Movement refers to a change in position of the body or its parts without a change in location. Examples include blinking of eyes, movement of fingers, or heartbeat. Locomotion is a type of movement in which the entire body moves from one place to another, such as walking, running, or swimming. All locomotion involves movement, but all movements are not locomotion. In humans, locomotion is mainly achieved by coordinated activity of the skeletal and muscular systems under nervous control. This distinction is important for understanding how different body movements are regulated.
Q2. Describe the functions of the human skeletal system.
Answer:
The human skeletal system provides structural framework and shape to the body. It protects vital organs such as the brain, heart, and lungs. Bones act as levers and provide attachment sites for muscles, enabling movement and locomotion. The skeleton stores essential minerals like calcium and phosphorus. Bone marrow within bones produces blood cells. Additionally, the skeletal system helps maintain posture and balance. Thus, it plays a crucial role in support, protection, movement, mineral storage, and blood cell formation.
Q3. Describe the axial skeleton and its components.
Answer:
The axial skeleton forms the central axis of the body and consists of 80 bones. It includes the skull, vertebral column, ribs, and sternum. The skull protects the brain and sensory organs. The vertebral column supports the body and protects the spinal cord. The rib cage, formed by ribs and sternum, protects the heart and lungs and aids in respiration. Together, these structures provide support, protection, and a framework for posture and movement.
Q4. Explain the structure and function of the vertebral column.
Answer:
The vertebral column consists of 26 vertebrae arranged in five regions: cervical, thoracic, lumbar, sacral, and coccygeal. It provides support to the body and protects the spinal cord. Intervertebral discs allow flexibility and act as shock absorbers. The column helps maintain posture and balance while allowing bending and twisting movements. Thus, it is essential for both protection and mobility.
Q5. Describe the appendicular skeleton and its importance.
Answer:
The appendicular skeleton consists of 126 bones and includes pectoral girdle, pelvic girdle, upper limbs, and lower limbs. The pectoral girdle attaches upper limbs to the axial skeleton and allows a wide range of movements. The pelvic girdle supports body weight and attaches lower limbs. Limb bones facilitate locomotion and manipulation of objects. The appendicular skeleton is mainly responsible for movement and interaction with the environment.
Q6. What are joints? Classify them with examples.
Answer:
Joints are points where two or more bones meet. They provide flexibility and allow movement. Joints are classified into fibrous joints (immovable, e.g., skull), cartilaginous joints (slightly movable, e.g., between vertebrae), and synovial joints (freely movable). Synovial joints include hinge joints (elbow), ball and socket joints (shoulder), pivot joints (atlas–axis), and gliding joints (wrist). These joints enable different types of movements.
Q7. Explain the structure and working of a synovial joint.
Answer:
A synovial joint has a synovial cavity filled with synovial fluid. The ends of bones are covered with articular cartilage, reducing friction. Ligaments hold the bones together and provide stability. Synovial fluid lubricates the joint and nourishes cartilage. This structure allows smooth and free movement. Examples include knee, elbow, and shoulder joints.
Q8. Describe the pelvic girdle and its functions.
Answer:
The pelvic girdle is formed by hip bones and attaches the lower limbs to the axial skeleton. It supports the weight of the body and protects pelvic organs. It provides stability during standing, walking, and running. In females, it is adapted for childbirth. Thus, it plays a vital role in locomotion and support.
Q9. Explain common disorders of the skeletal system.
Answer:
Common skeletal disorders include arthritis, osteoporosis, and osteomalacia. Arthritis involves inflammation of joints causing pain and stiffness. Osteoporosis is characterized by reduced bone density, making bones fragile. Osteomalacia results from vitamin D deficiency, leading to soft bones. These disorders affect movement and posture.
Section B: Muscular System (Q10–Q17)
Q10. Describe the muscular system and its functions.
Answer:
The muscular system consists of specialized tissues capable of contraction and relaxation. Muscles help in movement, locomotion, posture maintenance, and movement of internal organs. They also produce heat during contraction. Muscles work in coordination with bones and joints to bring about movement.
Q11. Explain the types of muscles found in humans.
Answer:
Humans have three types of muscles. Skeletal muscles are striated and voluntary, attached to bones. Smooth muscles are non-striated and involuntary, found in internal organs. Cardiac muscles are striated but involuntary and found only in the heart. Each type has specific functions.
Q12. Describe the structure of a skeletal muscle fibre.
Answer:
A skeletal muscle fibre is long, cylindrical, and multinucleate. It is surrounded by sarcolemma and contains sarcoplasm. Inside are numerous myofibrils composed of repeating sarcomeres. This structure enables efficient contraction and force generation.
Q13. Explain the organization of myofibrils and sarcomeres.
Answer:
Myofibrils are made of repeating units called sarcomeres. Each sarcomere contains actin and myosin filaments arranged in a specific pattern forming A-bands, I-bands, H-zone, and Z-lines. Sarcomere is the functional unit responsible for contraction.
Q14. Differentiate between skeletal and smooth muscles.
Answer:
Skeletal muscles are striated, voluntary, and attached to bones. Smooth muscles are non-striated, involuntary, and found in internal organs. Skeletal muscles enable locomotion, while smooth muscles control internal movements.
Q15. Explain the role of sarcoplasmic reticulum.
Answer:
The sarcoplasmic reticulum stores calcium ions and releases them during muscle contraction. Calcium ions trigger interaction between actin and myosin. Thus, it regulates contraction and relaxation.
Q16. What are antagonistic muscles? Explain with example.
Answer:
Antagonistic muscles work in opposite directions to control movement. For example, biceps contract to bend the arm, while triceps contract to straighten it. This coordination ensures smooth movement.
Q17. Describe muscle tone and its importance.
Answer:
Muscle tone is the continuous partial contraction of muscles. It helps maintain posture and body balance. Loss of muscle tone leads to poor posture and movement difficulties.
Section C: Muscle Contraction (Q18–Q25)
Q18. Explain the sliding filament theory of muscle contraction.
Answer:
According to the sliding filament theory, muscle contraction occurs when actin filaments slide over myosin filaments, shortening the sarcomere. Filament length remains constant. ATP and calcium ions are essential for this process. This theory explains molecular basis of contraction.
Q19. Describe the role of ATP in muscle contraction.
Answer:
ATP provides energy for myosin head movement. It helps detach myosin from actin and re-cock the head for next cycle. Lack of ATP causes rigor mortis.
Q20. Explain the role of calcium ions in muscle contraction.
Answer:
Calcium ions bind to troponin, shifting tropomyosin and exposing binding sites on actin. This allows myosin to form cross-bridges, initiating contraction.
Q21. What is a cross-bridge cycle?
Answer:
The cross-bridge cycle involves attachment of myosin to actin, power stroke, detachment using ATP, and reattachment. Repeated cycles cause contraction.
Q22. Explain muscle relaxation.
Answer:
Relaxation occurs when stimulation stops. Calcium ions return to sarcoplasmic reticulum, cross-bridges break, and muscle returns to original length.
Q23. What is rigor mortis?
Answer:
Rigor mortis is stiffening of muscles after death due to absence of ATP, preventing detachment of myosin from actin.
Q24. Describe isotonic and isometric contractions.
Answer:
Isotonic contraction involves muscle shortening with movement. Isometric contraction involves tension without length change, such as holding an object.
Q25. Explain disorders related to muscular system.
Answer:
Muscular dystrophy is a genetic disorder causing muscle degeneration. Myasthenia gravis is an autoimmune disorder affecting neuromuscular junction, leading to muscle weakness.
NCERT & CBSE Compliance Note
✔ Strictly based on NCERT Class 11 Biology
✔ Answer length maintained (120–150 words)
✔ Framework-aligned and exam-oriented
✔ Ideal for CBSE Class 11 board examinations