Answer: Inflammation or degeneration of joints causing pain and stiffness.
- A A genetic muscle disease that causes slow, progressive muscle weakness over time
- B Inflammation or degeneration of joints causing pain and stiffness
- C A fracture of one of the long bones, usually caused by trauma or a fall
- D A nerve disease that specifically affects motor neuron signaling pathways
Correct answer: B. Inflammation or degeneration of joints causing pain and stiffness
Explanation: Arthritis is inflammation and/or degeneration of joints. Rheumatoid arthritis: autoimmune, affects synovial membrane. Osteoarthritis: wear-and-tear degeneration of cartilage, most common in elderly. Both cause pain, stiffness, and reduced movement.
A sarcomere (Z line to Z line): during contraction the I band and H zone shorten as thin filaments slide over thick, while the A band stays the same length. Image: SlothMcCarty, CC BY-SA 3.0, via Wikimedia Commons.
Concept context
Types of movement, muscle contraction, skeletal system, joints, and disorders. Important for Class 11 and NEET.