Which is a false statement about skeletal muscle structure?a. A myofibril is composed of multiple muscle fibers.b. Most skeletal muscles attach to bones by connective-tissue tendons.c. Each end of a thick filament is surrounded by six thin filaments.d. A cross-bridge is a portion of the myosin molecule.e. Thin filaments contain actin, tropomyosin, and troponin.

Which is a false statement about skeletal muscle structure?a. A myofibril is composed of multiple muscle fibers.b. Most skeletal muscles attach to bones by connective-tissue tendons.c. Each end of a thick filament is surrounded by six thin filaments.d. A cross-bridge is a portion of the myosin molecule.e. Thin filaments contain actin, tropomyosin, and troponin.

BIOLOGY:CONCEPTS+APPL.(LOOSELEAF)

10th Edition

ISBN:9781305967359

Author:STARR

Publisher:STARR

Chapter32: Structural Support And Movement

Section: Chapter Questions

Problem 12SA

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What structure on a muscle fiber is composed of largely two varieties of contractile proteins--actin and myosin--which slide past each other during muscle activity to bring about shortening or contraction of muscle cells? A. myofilament B. sarcoplasmic reticulum C. transverse tububle D. sarcomeres
What do skeletal muscle contractions share in common with smooth muscle contractions?a. Both types of contractions do not require calcium ions for a contraction to occur.b. Both types of contractions generate little force or a weak force.c. Both types of contractions consume very little ATP.d. Both types of contractions result from thick and thin filaments sliding past one another.
What structure in skeletal muscle cells functions in calcium storage? a.myofibrillar network b.sarcoplasmic reticulum c.intermediate filament network d.mitochondria
The Sarcomere 2 Thin filaments are often named for which protein? a. actin b. myosin c. troponin d. tropomyosin
What might happen if skeletal muscle lacked tropomyosin? A. The striation pattern would disappear. B. Ca2+ levels in the muscle would decrease. C. Actin and myosin would not be able to form cross-bridges. D. Acetylcholine would not be released into the synaptic cleft. E. Myosin and actin would form cross-bridges whenever ATP is available.
When sarcomeres contract during muscle contraction, which of the following occurs? A. The myosin filaments lengthen. B. The myosin filaments "walk" along the actin microfilaments. C. The myosin filaments shorten. D. The actin filaments shorten.
Which statement about striated skeletal muscle is true? A. The tension generated by a muscle is invariable. B. Mechanical summation of twitches in a muscle fiber leads to a graded increase in the tension that is above that generated by a single twitch. C. A single action potential arriving at the neuromuscular junction is not sufficient to cause a muscle fiber to twitch. D. Muscle twitches are able to mechanically sum when Ca2+ is quickly and completely removed from the sarcoplasm between action potentials. E. An action potential in the muscle cell activates contraction by releasing Na+ into the sarcoplasm.
Which protein is not part of the thin filament in a muscle fiber? A. Actin B. Myosin C. Tropomyosin D. Troponin
The primary role of calcium in skeletal muscle contraction? Select one: a. Cause depolarization of the sarcolemma b. Cross-bridge cycle between actin and myosin C. Provides energy necessary for contraction d. Causes muscle relaxation e. Regulate ionic composition of the cell
Which choice lists the components of a muscle from the smallest unit to the largest unit? A. myofibril, filament, sarcomere, muscle fiber B. filament, sarcomere, myofibril, muscle fiber C. sarcomere, filament, muscle fiber, myofibril D. muscle fiber, filament, sarcomere, myofibril
When a muscle fiber is stretched from 60% of its optimal length to Lo, what change or changes are happening on the cellular level (MULTIPLE SELECT)? A. Increased calcium release from the SR B. Increased firing of action potentials from the alpha motor neuron C. Increased rate of myosin ATPase activity D. Increased number of actin-myosin bridges E. Increased stretch on titin, producing more passive force
Which of the following statements best describes the sliding filament mechanism of muscle contraction? a. Actin and myosin filaments do not shorten, but rather, slide past each other. b. Actin and myosin filaments shorten and slide past each other. c. As they slide past each other, actin filaments shorten, but myosin filaments do not shorten. d. As they slide past each other, myosin filaments shorten, but actin filaments do not shorten.