Chapter 17 of Class 11 Biology is Locomotion and Movement. It covers the types of movement, the human skeletal and muscular systems, and the sliding filament mechanism of muscle contraction. These Class 11 Biology Chapter 17 solutions are also useful as quick revision notes before exams.
Types of Movement
Amoeboid (via pseudopodia, e.g. WBCs), ciliary (via cilia, e.g. respiratory tract lining), and muscular (via muscle contraction, e.g. limb movement) movement.
Types of Muscle
Skeletal (striated): voluntary, attached to bones. Smooth (unstriated): involuntary, in internal organs. Cardiac: involuntary, striated, only in heart.
Muscle Contraction: Sliding Filament Theory
A muscle fibre contains myofibrils made of thick (myosin) and thin (actin) filaments arranged in repeating units called sarcomeres. During contraction, myosin heads bind actin (forming cross-bridges) and pull thin filaments inward, sliding them past thick filaments, shortening the sarcomere — without the filaments themselves changing length. Requires Ca²⁺, ATP, and the regulatory proteins troponin and tropomyosin.
Human Skeletal System
206 bones, divided into axial skeleton (skull, vertebral column, ribs, sternum — 80 bones) and appendicular skeleton (limb bones and girdles — 126 bones).
Joints
Fibrous joints (immovable, e.g. skull sutures), cartilaginous joints (slightly movable, e.g. between vertebrae), synovial joints (freely movable, e.g. ball-and-socket at hip/shoulder, hinge at knee/elbow).
Disorders
Myasthenia gravis (autoimmune, affects neuromuscular junction), tetany (rapid muscle spasms from low Ca²⁺), arthritis (joint inflammation), osteoporosis (age-related bone density loss).
Class 11 Biology Chapter 17 – Notes and Extra Questions
Along with these NCERT Solutions, students can also use the Class 11 Biology Chapter 17 Extra Questions and Class 11 Biology Chapter 17 Revision Notes for quick revision and extra practice.
