Question 1

During muscle contraction, which filament slides toward the center of the sarcomere, resulting in muscle shortening?

Accepted Answer

Actin

Question 2

Which protein blocks the myosin binding sites on actin in a relaxed muscle?

Accepted Answer

Tropomyosin

Question 3

If calcium ions are not present, what happens to the myosin binding sites on actin?

Accepted Answer

They are blocked by tropomyosin.

Question 4

Which of the following is the correct sequence of events for the sliding filament theory?

Accepted Answer

Myosin binds to actin, pulls actin toward the M line, sarcomere shortens.

Question 5

A patient with myosin storage myopathy would most likely show which of the following changes in their sarcomere structure?

Accepted Answer

Clumping of thick filaments

Question 6

Which region of the sarcomere contains only actin filaments?

Accepted Answer

I Band

Question 7

What is the function of titin in the sarcomere?

Accepted Answer

Anchors myosin to the M line and provides elasticity

Question 8

Which of the following best describes the A band in a sarcomere?

Accepted Answer

Region containing both actin and myosin filaments

Question 9

During contraction, which region of the sarcomere decreases in length?

Accepted Answer

I Band

Question 10

If the troponin molecules are non-functional, what would happen to muscle contraction?

Accepted Answer

Myosin binding sites would remain blocked, preventing contraction.

Question 11

Which equation best represents the relationship between force ($F$), cross-sectional area ($A$), and tension ($T$) in a muscle fiber?

Accepted Answer

$F = T 	imes A$

Question 12

Which of the following is NOT found in the A band?

Accepted Answer

M Line

Question 13

Which region of the sarcomere is the same length as the actin filament?

Accepted Answer

I Band

Question 14

What is the role of calcium ions in muscle contraction?

Accepted Answer

Bind to troponin, causing tropomyosin to move and expose myosin binding sites

Question 15

Which of the following best describes the change in the H zone during muscle contraction?

Accepted Answer

It gets shorter and may disappear.

Question 16

Which protein is directly responsible for pulling actin filaments during contraction?

Accepted Answer

Myosin

Question 17

Which of the following is a structural protein that helps the sarcomere retain its shape?

Accepted Answer

Titin

Question 18

What would happen to muscle contraction if tropomyosin was absent from the actin filament?

Accepted Answer

Myosin binding sites would always be exposed, leading to continuous contraction.

Question 19

Which band or zone does NOT change length during muscle contraction?

Accepted Answer

A Band

Question 20

Which of the following best describes the M line in the sarcomere?

Accepted Answer

Anchors myosin filaments at the center of the sarcomere

Sarcomere Structure and Sliding Filament Theory: Study Notes for Anatomy & Physiology

Study Guide - Practice Questions