Bio 2160 Crousillac Exam 4 Latest
Questions With 100% Correct Answers
2025-2026 Updated.
What is an individual muscle cell? - Answer Muscle Fiber
What are the clusters of proteins within each muscle cell? - Answer Myofibrils
A membrane has (single/multiple) nuclei - Answer Multiple (multinucleated)
Muscles cells (do/do not) divide in adulthood. - Answer do not
When muscle tissue dies, it (does/does not) grow back - Answer does not
Neuron that innervates a muscle cell. - Answer Motor Neuron
What is the name of the endoplasmic reticulum in muscle cells? - Answer Sarcoplasmic
Reticulum
What is stored in the sarcoplasmic reticulum? - Answer Calcium
Where are T-Tubules found? - Answer in the muscle membrane & runs deep into the
myofibrils
Where is the motor end plate found? - Answer Muscle Cell Membrane
Explain the process of moving your finger... - Answer 1. Acetylcholine gets released from
motor neurons then binds to receptors on the end plate (depolarization).
2. Channels open: Sodium comes in, Potassium goes out.
3. End plate potential develops action potentials.
All contractions happen (at once/in a sequence) - Answer in a sequence
Thick and thin filaments come in contact with each other at _______. - Answer crossbridges
,What two things do all muscle contractions require? - Answer Calcium & ATP
What keeps myosin from being in contact with actin? - Answer Troponin
What moves tropomyosin around?
-calcium binding site, actin binding site, tropomyosin binding site - Answer Troponin
What covers up the binding site on actin when muscles relax?
-extends along thin filaments, masks myosin binding site in absence of calcium - Answer
Tropomyosin
How does a cramp occur? - Answer By involuntary skeletal muscle contraction
Name the regulatory proteins: - Answer Tropomyosin & Troponin
Made up of two strands of actin that form double helix - Answer Thin Filaments
Made up of myosin dimers bound together at tails, binding sites on heads (crossbridges) for
actin, ATPase site - Answer Thick Filaments
______ gives permission for contractions to occur. - Answer Calcium
Name the steps of muscle contraction: - Answer 1. Motor Neuron Action Potential
2. End plate potential (excitation)
3. Increase in muscle cell calcium levels
4. Troponin and Tropomyosin conformation change
5. Crossbridge cycling to sliding filaments (CONTRACTION)
Calcium binds to ______ to move ______ out of the way, which causes a contraction. - Answer
Troponin/ Tropomyosin
Another name for calcium channels in the sarcoplasmic reticulum - Answer Ryanodine
Receptors
, What is the job of DHP receptors? - Answer detect action potentials and when they do, they
change shape and pull open calcium channels (Ryanodine receptors) so calcium goes out of SR
into the muscle cell.
-voltage sensor
The majority of calcium needed in a muscle cell comes from ______ receptors. - Answer DHP
When ATP binds to myosin, myosin now has a ______ affinity for actin. - Answer Low
When ATP binds to myosin, the muscle contraction (starts/stops) and myosin lets go of actin. -
Answer stops
When attached to ADP, myosin has a _____ affinity for actin. - Answer High
When myosin is attached to ADP, actin binds to it, forming a ________ between myosin and
actin. - Answer Cross-Bridge
What causes the myosin head to close causing the power stroke? - Answer Release of an
inorganic phosphate
You need more ______ to relax muscles.
-this is why dead bodies are stiff - Answer ATP
Name the ways muscle contraction is terminated: - Answer 1. Motor neuron input
terminates
2. End plate potentials terminate
3. High myoplasmic calcium concentration shuts SR calcium channels
4. Active calcium uptake through SERCA pumps on SR move calcium from cytoplasm to SR.
5. Calcium dissociated from troponin
6. Tropomyosin covers myosin binding sites on actin
The most work that a single action potential can produce.
-The mechanical response or change in force/tension (measured in grams) of an individual
muscle fiber, motor unit, or whole muscle to a single action potential - Answer Twitch
Questions With 100% Correct Answers
2025-2026 Updated.
What is an individual muscle cell? - Answer Muscle Fiber
What are the clusters of proteins within each muscle cell? - Answer Myofibrils
A membrane has (single/multiple) nuclei - Answer Multiple (multinucleated)
Muscles cells (do/do not) divide in adulthood. - Answer do not
When muscle tissue dies, it (does/does not) grow back - Answer does not
Neuron that innervates a muscle cell. - Answer Motor Neuron
What is the name of the endoplasmic reticulum in muscle cells? - Answer Sarcoplasmic
Reticulum
What is stored in the sarcoplasmic reticulum? - Answer Calcium
Where are T-Tubules found? - Answer in the muscle membrane & runs deep into the
myofibrils
Where is the motor end plate found? - Answer Muscle Cell Membrane
Explain the process of moving your finger... - Answer 1. Acetylcholine gets released from
motor neurons then binds to receptors on the end plate (depolarization).
2. Channels open: Sodium comes in, Potassium goes out.
3. End plate potential develops action potentials.
All contractions happen (at once/in a sequence) - Answer in a sequence
Thick and thin filaments come in contact with each other at _______. - Answer crossbridges
,What two things do all muscle contractions require? - Answer Calcium & ATP
What keeps myosin from being in contact with actin? - Answer Troponin
What moves tropomyosin around?
-calcium binding site, actin binding site, tropomyosin binding site - Answer Troponin
What covers up the binding site on actin when muscles relax?
-extends along thin filaments, masks myosin binding site in absence of calcium - Answer
Tropomyosin
How does a cramp occur? - Answer By involuntary skeletal muscle contraction
Name the regulatory proteins: - Answer Tropomyosin & Troponin
Made up of two strands of actin that form double helix - Answer Thin Filaments
Made up of myosin dimers bound together at tails, binding sites on heads (crossbridges) for
actin, ATPase site - Answer Thick Filaments
______ gives permission for contractions to occur. - Answer Calcium
Name the steps of muscle contraction: - Answer 1. Motor Neuron Action Potential
2. End plate potential (excitation)
3. Increase in muscle cell calcium levels
4. Troponin and Tropomyosin conformation change
5. Crossbridge cycling to sliding filaments (CONTRACTION)
Calcium binds to ______ to move ______ out of the way, which causes a contraction. - Answer
Troponin/ Tropomyosin
Another name for calcium channels in the sarcoplasmic reticulum - Answer Ryanodine
Receptors
, What is the job of DHP receptors? - Answer detect action potentials and when they do, they
change shape and pull open calcium channels (Ryanodine receptors) so calcium goes out of SR
into the muscle cell.
-voltage sensor
The majority of calcium needed in a muscle cell comes from ______ receptors. - Answer DHP
When ATP binds to myosin, myosin now has a ______ affinity for actin. - Answer Low
When ATP binds to myosin, the muscle contraction (starts/stops) and myosin lets go of actin. -
Answer stops
When attached to ADP, myosin has a _____ affinity for actin. - Answer High
When myosin is attached to ADP, actin binds to it, forming a ________ between myosin and
actin. - Answer Cross-Bridge
What causes the myosin head to close causing the power stroke? - Answer Release of an
inorganic phosphate
You need more ______ to relax muscles.
-this is why dead bodies are stiff - Answer ATP
Name the ways muscle contraction is terminated: - Answer 1. Motor neuron input
terminates
2. End plate potentials terminate
3. High myoplasmic calcium concentration shuts SR calcium channels
4. Active calcium uptake through SERCA pumps on SR move calcium from cytoplasm to SR.
5. Calcium dissociated from troponin
6. Tropomyosin covers myosin binding sites on actin
The most work that a single action potential can produce.
-The mechanical response or change in force/tension (measured in grams) of an individual
muscle fiber, motor unit, or whole muscle to a single action potential - Answer Twitch
