Locomotion and Movement MCQs for NEET — Zoology Questions with Answers

Synovial joints are the most common and movable type of joints in the human body. They include ball and socket joints (e.g., shoulder and hip joints), pivot joints (e.g., the joint between the first and second cervical vertebrae), and hinge joints (e.g., elbow and knee). Therefore, the correct option is 'All the above'.

The human cranium consists of 8 bones. These bones include the frontal bone, two parietal bones, two temporal bones, the occipital bone, the sphenoid bone, and the ethmoid bone. These bones protect the brain and support the structures of the face.

Red muscles, also known as slow-twitch muscles, have a high content of myoglobin. Myoglobin is a red pigment that stores oxygen, which is essential for aerobic respiration. This makes red muscles more suited for endurance activities.

Synovial fluid is present in ball and socket joints and acts as a lubricant to reduce friction between the articular cartilage of synovial joints during movement.

The extremities of long bones are covered by hyaline cartilage. This type of cartilage provides a smooth, slippery surface that reduces friction and absorbs shock in the joint.

During muscle contraction, the size of the A-bands remains the same, the size of the H-zone becomes smaller, and the size of the I-bands decreases. This is because, during contraction, the actin filaments slide over the myosin filaments, causing the sarcomere to shorten while the A-band remains unchanged. The overlapping of actin and myosin filaments reduces the H-zone and I-bands.

Lactic acid accumulates in a fatigued muscle. When muscles are used extensively and oxygen is not available in sufficient quantities, anaerobic respiration takes place, leading to the production of lactic acid. This acid build-up causes a decrease in pH within the muscle cells, contributing to muscle fatigue and soreness.

Calcium ions (Ca²⁺) are essential for muscle contraction. They are released from the sarcoplasmic reticulum into the muscle cytoplasm in response to an action potential. Calcium ions bind to troponin, causing a conformational change that allows myosin to bind to actin, initiating the contraction process.

The ends of long bones are covered by cartilage. Cartilage is a smooth, elastic tissue that reduces friction and acts as a cushion between bones, allowing for smooth movement at the joints.

The acromion process is a bony projection on the scapula (shoulder blade) and is part of the pectoral girdle. It forms the highest point of the shoulder and serves as an attachment site for muscles.