Final answer:
A scientist can identify if a muscle is skeletal, cardiac, or smooth by observing the striations and nuclei arrangement under a light microscope. Striated and multinucleated fibers indicate skeletal muscle, striated with single nuclei are cardiac muscle, and non-striated indicates smooth muscle.
Step-by-step explanation:
A scientist using a light microscope to observe muscle tissue can identify whether the muscle moved the skeleton, the heart, or other types of internal organs by analyzing its cellular structure and organization. This is because muscle tissue is classified into three distinct types based on structure and function: skeletal muscle, cardiac muscle, and smooth muscle.
Skeletal muscle tissue has a distinctive striated appearance due to the regular arrangement of actin and myosin contractile proteins in the cytoplasm of the muscle fibers, which appears as stripes, or striations, visible under high magnification. These muscle fibers are also multinucleated structures, which is another distinguishable feature. In contrast, smooth muscle does not display striations and is not multinucleated. Cardiac muscle tissue, like skeletal muscle, has striations but differs in that cardiac muscle fibers typically have a single nucleus and are connected in a pattern that allows the heart to contract as one unit.
Therefore, by identifying the presence of striations and the arrangement and number of nuclei, a scientist can determine if a muscle is skeletal, indicating it moves the skeleton, cardiac if it moves the heart, or smooth if it is involved in moving internal organs not under voluntary control.