Microscopic Components of Muscles

What is the basic structural unit of a muscle fiber?

• myofibril

• sarcomere

• myosin

• actin

Which protein is responsible for muscle contraction?

• troponin and tropomyosin

• collagen and elastin

• hemoglobin and myoglobin

• actin and myosin

What is the organization of sarcomeres within a muscle fiber?

• Sarcomeres are organized in a spiral pattern within a muscle fiber.

• Sarcomeres are only found at the ends of a muscle fiber.

• Sarcomeres are organized in a repeating pattern along the length of the muscle fiber.

• Sarcomeres are randomly distributed within a muscle fiber.

Explain the sliding filament theory.

• The sliding filament theory explains how muscles contract by the sliding of actin and myosin filaments.

• The sliding filament theory explains how muscles contract by the sliding of actin and tropomyosin filaments.

• The sliding filament theory explains how muscles contract by the sliding of myosin and troponin filaments.

• The sliding filament theory explains how muscles contract by the sliding of actin and troponin filaments.

Describe the process of muscle contraction.

• Muscle contraction is the process in which muscle fibers generate tension and shorten in length.

• Muscle contraction is the process in which muscle fibers relax and lengthen.

• Muscle contraction is the process in which muscle fibers do not generate tension.

• Muscle contraction is the process in which muscle fibers only generate tension but do not shorten in length.

What are the two main proteins involved in the interaction between myosin and actin?

• actin and myosin

• actin and ATP

• myosin and myosin

• actin and actin

How does the sliding filament theory explain muscle contraction?

• The sliding filament theory explains muscle contraction by stating that during contraction, the thin actin filaments slide over the thick myosin filaments, causing the sarcomeres to shorten.

• The sliding filament theory explains muscle contraction by stating that the thin actin filaments remain stationary while the thick myosin filaments contract, causing the sarcomeres to lengthen.

• The sliding filament theory explains muscle contraction by stating that the thin actin filaments detach from the thick myosin filaments, causing the sarcomeres to lengthen.

• The sliding filament theory explains muscle contraction by stating that the thin actin filaments push the thick myosin filaments, causing the sarcomeres to lengthen.

What is the role of calcium ions in muscle contraction?

• Calcium ions are released from the muscle during relaxation.

• Calcium ions bind to troponin and initiate muscle contraction.

• Calcium ions have no role in muscle contraction.

• Calcium ions inhibit muscle contraction.

What happens to the sarcomere during muscle contraction?

• The sarcomere remains the same length.

• The sarcomere lengthens.

• The sarcomere becomes thicker.

• The sarcomere shortens.

Explain the structure of a muscle fiber.

• A muscle fiber is a short, flat cell that makes up the muscle tissue.

• Sarcomeres contain only thick filaments and no thin filaments.

• A muscle fiber is a long, cylindrical cell that makes up the muscle tissue. It is composed of myofibrils, which are made up of sarcomeres. Sarcomeres contain thick and thin filaments that slide past each other during muscle contraction. The muscle fiber is surrounded by a plasma membrane called the sarcolemma and is filled with cytoplasm called sarcoplasm. The sarcoplasm contains many mitochondria for energy production and stores calcium ions needed for muscle contraction.

• The sarcolemma is a layer of connective tissue that surrounds the muscle fiber.