BIO 251
Bio 251 Exam Questions and Answers
Correctly Approved 2025
A muscle fiber can be innervated by multiple motor neurons.
a) True
b) False - Correct Ans-f
The contraction time of a skeletal muscle is the time between initiation of stimulation
and
peak contraction of the muscle.
a) True
b) False - Correct Ans-f
During contraction of all types of muscle cells, Ca++ initiates contraction by entering the
cytoplasm of the muscle cell by the process of facilitated diffusion.
a) True
b) False - Correct Ans-t
The plateau phase of the contractile cell action potential is caused by Na+ entering the
cell.
a) True
b) False - Correct Ans-f
The radii of arterioles can be adjusted independently to variably distribute cardiac output
among organs.
a) True
b) False - Correct Ans-t
Platelets contain actin and myosin.
a) True
b) False - Correct Ans-t
Ischemic heart disease is
a) Rapid but regular depolarizations and contractions
b) Rapid irregular uncoordinated depolarizations contractions
c) Action potentials not conducted between atria and ventricles
d) Over excitation of non-SA node autorhythmic regions of heart
e) Reduced blood supply to heart - Correct Ans-e
The steps of synaptic transmission at a neuromuscular junction are listed below, out of
order.
Choose the correct order.
1. Acetylcholine binds to receptors on muscle cell.
2. Acetylcholine is released.
BIO 251
, BIO 251
3. A graded potential is produced on the motor end plate.
4. An action potential is produced on the muscle cell membrane.
5. Channels for both sodium and potassium are opened.
6. Voltage-gated calcium channels on the plasma membrane open.
7. An action potential arrives at the axon terminal. - Correct Ans-7621534
The parasympathetic nervous system can act as a stimulus to which types of muscle
cells?
a) Single-unit smooth
b) Cardiac autorhythmic
c) Cardiac contractile
d) All the above
e) a and b only - Correct Ans-e
. In Fig 1, the muscle length that gives maximum contraction is
a) 60 to 80
b) 80 to 100
c) 100 to 120
d) 120 to 140
e) 140 to 160 - Correct Ans-c
The rapid depolarization of cardiac contractile cell membranes when threshold is
reached is
caused by Ca++ entering the cell.
a) True
b) False - Correct Ans-f
Increased venous return will result in a decreased cardiac output.
a) True
b) False - Correct Ans-b
Indicate which is the proper sequence of blood flow though the circulatory system:
1. right atrium 6. pulmonary vein
2. left atrium 7. lungs
3. right ventricle 8. systemic tissues
4. left ventricle 9. aorta
5. pulmonary artery 10. venae cavae - Correct Ans-10-1-3-5-7-6-2-4-9-8
Place the sequence of a skeletal muscle contraction in order:
1. Ca++ binds to troponin
2. End Plate Potential becomes Action Potential on surface of membrane
3. Tropomyosin moves aside
4. Actin binds to myosin
5. Action potential moves into T tubules
6 Ca++ released from SR
7. Cross-bridge cycling occurs
BIO 251
Bio 251 Exam Questions and Answers
Correctly Approved 2025
A muscle fiber can be innervated by multiple motor neurons.
a) True
b) False - Correct Ans-f
The contraction time of a skeletal muscle is the time between initiation of stimulation
and
peak contraction of the muscle.
a) True
b) False - Correct Ans-f
During contraction of all types of muscle cells, Ca++ initiates contraction by entering the
cytoplasm of the muscle cell by the process of facilitated diffusion.
a) True
b) False - Correct Ans-t
The plateau phase of the contractile cell action potential is caused by Na+ entering the
cell.
a) True
b) False - Correct Ans-f
The radii of arterioles can be adjusted independently to variably distribute cardiac output
among organs.
a) True
b) False - Correct Ans-t
Platelets contain actin and myosin.
a) True
b) False - Correct Ans-t
Ischemic heart disease is
a) Rapid but regular depolarizations and contractions
b) Rapid irregular uncoordinated depolarizations contractions
c) Action potentials not conducted between atria and ventricles
d) Over excitation of non-SA node autorhythmic regions of heart
e) Reduced blood supply to heart - Correct Ans-e
The steps of synaptic transmission at a neuromuscular junction are listed below, out of
order.
Choose the correct order.
1. Acetylcholine binds to receptors on muscle cell.
2. Acetylcholine is released.
BIO 251
, BIO 251
3. A graded potential is produced on the motor end plate.
4. An action potential is produced on the muscle cell membrane.
5. Channels for both sodium and potassium are opened.
6. Voltage-gated calcium channels on the plasma membrane open.
7. An action potential arrives at the axon terminal. - Correct Ans-7621534
The parasympathetic nervous system can act as a stimulus to which types of muscle
cells?
a) Single-unit smooth
b) Cardiac autorhythmic
c) Cardiac contractile
d) All the above
e) a and b only - Correct Ans-e
. In Fig 1, the muscle length that gives maximum contraction is
a) 60 to 80
b) 80 to 100
c) 100 to 120
d) 120 to 140
e) 140 to 160 - Correct Ans-c
The rapid depolarization of cardiac contractile cell membranes when threshold is
reached is
caused by Ca++ entering the cell.
a) True
b) False - Correct Ans-f
Increased venous return will result in a decreased cardiac output.
a) True
b) False - Correct Ans-b
Indicate which is the proper sequence of blood flow though the circulatory system:
1. right atrium 6. pulmonary vein
2. left atrium 7. lungs
3. right ventricle 8. systemic tissues
4. left ventricle 9. aorta
5. pulmonary artery 10. venae cavae - Correct Ans-10-1-3-5-7-6-2-4-9-8
Place the sequence of a skeletal muscle contraction in order:
1. Ca++ binds to troponin
2. End Plate Potential becomes Action Potential on surface of membrane
3. Tropomyosin moves aside
4. Actin binds to myosin
5. Action potential moves into T tubules
6 Ca++ released from SR
7. Cross-bridge cycling occurs
BIO 251
