Zoology MCQs for NEET — Practice Questions with Answers

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.

In mammals, the lower jaw is made of the mandible. The mandible is the largest and strongest bone of the face, and it holds the lower teeth in place.

The acetabulum is a concave surface of the pelvis (part of the pelvic girdle) where the head of the femur fits to form the hip joint. It is a crucial part of the pelvic anatomy because it allows for the movement and support of the leg.

The functional unit of a contractile system in striated muscle is the sarcomere. A sarcomere is the segment between two neighboring Z-lines (or Z-discs) and is the smallest functional unit of muscle fiber responsible for muscle contraction. It contains actin and myosin filaments whose interaction leads to muscle contraction.

Fibrous joints are present between the bones of the skull. These joints, also known as sutures, are immovable and are connected by dense connective tissue. They play a crucial role in protecting the brain by providing a rigid structure.