Locomotion and Movement MCQs for NEET — Zoology Questions with Answers

The three main types of muscles present in organisms are striated muscle, visceral muscle, and cardiac muscle. Striated muscles, also known as skeletal muscles, are responsible for voluntary movements. Visceral muscles, also referred to as smooth muscles, are found in internal organs and are responsible for involuntary movements. Cardiac muscle is found only in the heart and is responsible for pumping blood. NEET students should remember these three types as they encompass all muscle types in the human body.

Cardiac muscle contains all the mentioned bands: Intercalated discs, A-bands, and I-bands. Intercalated discs are unique to cardiac muscle and allow for synchronized contraction. A-bands are the dark bands, and I-bands are the light bands in the striated muscle structure. Therefore, the correct answer is 'All 1.2.3'.

In muscle physiology, the isotropic band (I-band) and the anisotropic band (A-band) refer to regions within the sarcomere. The I-band contains only thin filaments and appears lighter under a microscope, while the A-band contains the entire length of the thick filaments and appears darker. Thus, the correct answer is 'I - band, A - band'.

The M-line is located in the center of the H region within the sarcomere. The M-line serves as the attachment site for the thick filaments and helps maintain their alignment. Therefore, the correct answer is 'M- line'.

The space between two successive Z-bands in a muscle fiber is known as the sarcomere. A sarcomere is the basic unit of striated muscle tissue responsible for muscle contraction. It is composed of repeating units of actin and myosin filaments. Understanding this structural organization helps in studying how muscles contract and generate force.

The Z-band, also known as the Z-line or Z-disc, is sometimes referred to as the Krause membrane. It marks the boundary between adjacent sarcomeres in muscle fibers. The Z-band plays a crucial role in muscle contraction by anchoring the actin filaments and helping maintain the structural integrity of the muscle fiber.

The functional unit of skeletal muscle is called the sarcomere. Sarcomeres are the repeating structural units within myofibrils, bordered by Z-lines. They contain the actin and myosin filaments whose interactions are responsible for muscle contraction. This understanding is fundamental for comprehending how muscles work at a microscopic level.

Actin fibers exist in two main forms: G-actin (globular actin) which are monomers, and F-actin (filamentous actin) which are polymerized chains of G-actin. Hence, options 1 and 3 together (Both 1 & 3) are correct.

Troponin is a complex of three regulatory proteins that are involved in muscle contraction. It is a small, globular protein complex that binds to tropomyosin and helps regulate the interaction of actin and myosin in muscle fibers.