Zoology MCQs for NEET — Practice Questions with Answers

During vigorous exercise, the body's demand for energy increases significantly. When oxygen levels are insufficient for aerobic respiration, the body switches to anaerobic respiration. In this process, glucose is converted into lactic acid to produce energy quickly. This is why muscles may feel sore after intense exercise due to lactic acid buildup.

Synovial fluid is a viscous fluid found in the cavities of synovial joints, which are also known as freely movable joints. This fluid acts as a lubricant, reducing friction between the articular cartilages of synovial joints during movement, thereby facilitating smooth and painless joint motion.

Red muscles, also known as slow-twitch muscles, are rich in mitochondria. Mitochondria are the powerhouse of the cell and provide the energy required for continuous and extended muscle contractions. This is why red muscles have high endurance but generate less force compared to white muscles.

The joint between the atlas (the first cervical vertebra) and the axis (the second cervical vertebra) is a pivot joint. This type of joint allows for rotational movement, which is why we can turn our heads from side to side.

The femur, or thigh bone, is the longest bone in the human body. It extends from the hip to the knee and plays a crucial role in supporting the weight of the body and allowing for leg movement.

ATP-ase needed for muscle contraction is present in the myosin heads. During muscle contraction, ATP binds to myosin, which is then hydrolyzed by ATP-ase to provide the energy necessary for the myosin heads to attach to actin filaments and produce a contraction.

Both the statements are true and Reason (R) is the correct explanation for Assertion (A). Skeletal muscles are also called striated muscles because they have a banded appearance due to the arrangement of actin and myosin filaments in repeating units called sarcomeres, which form horizontal belts.

Statement (A) is true as cardiac muscles contract quickly, rhythmically, and powerfully, and they do not fatigue easily. However, Reason (R) is false because intercalated discs are present in cardiac muscle. These discs contain gap junctions that facilitate the synchronized contraction of cardiac muscle cells.