A protein that helps form the structure of cells and is involved in muscle contraction by binding to myosin. Thin filament, I-band.

• Actin

• Myosin

• Sarcomere

• Sarcoplasm

• Sarcoplasmic Reticulum

Answer explanation

The correct choice is Actin because it is a protein involved in muscle contraction by binding to myosin and helps form the structure of cells. It is part of the thin filament in the I-band of the sarcomere.

The basic unit of a muscle cell where contraction happens, made up of overlapping actin and myosin filaments.

• Actin

• Myosin

• Sarcomere

• Sarcoplasm

• Sarcoplasmic Reticulum

Answer explanation

The correct answer is 'Sarcomere' as it is the basic unit of a muscle cell where contraction occurs, consisting of overlapping actin and myosin filaments.

A protein that helps muscles contract by pulling on actin filaments. Thick filament, A-band.

• Actin

• Myosin

• Sarcomere

• Sarcoplasm

• Sarcoplasmic Reticulum

Answer explanation

The protein that helps muscles contract by pulling on actin filaments in the A-band is myosin, not actin, sarcomere, sarcoplasm, or sarcoplasmic reticulum.

The gel-like substance within muscle cells where important cellular activities occur.

• Actin

• Myosin

• Sarcomere

• Sarcoplasm

• Sarcoplasmic Reticulum

Answer explanation

The sarcoplasm is the gel-like substance within muscle cells where important cellular activities occur, making it the correct choice.

A network of membrane-bound tubules within muscle cells that stores and releases calcium ions needed for muscle contraction.

• Actin

• Myosin

• Sarcomere

• Sarcoplasm

• Sarcoplasmic Reticulum

Answer explanation

The sarcoplasmic reticulum is a network of membrane-bound tubules within muscle cells that stores and releases calcium ions needed for muscle contraction.

A tough connective tissue layer that surrounds the entire outermost layer of muscles.

• Epimysium

• Perimysium

• Endomysium

• Fascicle

• Myofibril

Answer explanation

The correct choice is Epimysium, which is the tough connective tissue layer that surrounds the entire outermost layer of muscles.

Connective tissue that surrounds bundles of muscle fibers (fascicles) within a muscle.

• Epimysium

• Perimysium

• Endomysium

• Fascicle

• Myofibril

Answer explanation

The perimysium is the connective tissue that surrounds bundles of muscle fibers (fascicles) within a muscle, making it the correct choice.

Connective tissue that surrounds individual muscle fibers (myofibrils) within a muscle fascicle.

• Epimysium

• Perimysium

• Endomysium

• Fascicle

• Myofibril

Answer explanation

The endomysium is the connective tissue that surrounds individual muscle fibers (myofibrils) within a muscle fascicle.

A bundle of muscle fibers (muscle cells) within a muscle, surrounded by connective tissue called perimysium.

• Epimysium

• Perimysium

• Endomysium

• Fascicle

• Myofibril

Answer explanation

A fascicle is a bundle of muscle fibers within a muscle, surrounded by perimysium connective tissue.

A long, thread-like structure found within muscle fibers (muscle cells), composed of repeating units called sarcomeres. The smallest of the fibers inside of muscle tissue.

• Epimysium

• Perimysium

• Endomysium

• Fascicle

• Myofibril

Answer explanation

The correct choice is Myofibril, which is a long, thread-like structure found within muscle fibers composed of sarcomeres, the smallest fibers inside muscle tissue.