AP Biology
Name: ____________________
BioFlix Study Sheet for How Neurons Work
Refer to your book, BioFlix Animation, and BioFlix Tutorials if you need help.
Part I: The Action Potential - For each of the following events in an action potential, draw the axon
membrane of the neuron. Be sure to indicate where charge is positive and negative, and draw ions entering
or exiting the neuron where appropriate. Describe the key events.
Neuron
Resting potential
Stimulus begins to
change the
distribution of charge
across the membrane
Action potential:
Sodium channels open
Action potential:
Sodium channels close
and potassium
channels open
Neuron returns to
resting potential
Drawing of Axon Membrane
Description of Key Events
Part II: Conduction of an Action Potential - Draw three stages in the conduction of an action potential. For
each stage, indicate where the action potential is taking place. Be sure to indicate where charge is positive
and negative, and draw ions entering and exiting the neuron where appropriate. Describe the events.
1.
Stage
Drawing of Axon Membrane
Events
2.
3.
AP Biology
BioFlix Quiz – How Neurons Work
Write the answer to each question in the blank. Note that the answer options may not match the online quiz.
____1. When a neuron is at its resting potential
A. gated sodium channels are open.
B. sodium-potassium pumps transport sodium ions into the cell.
C. there are more potassium ions inside the neuron than outside.
D. the inside of the cell is positively charged relative to the outside.
E. sodium-potassium pumps transport both sodium and potassium ions out of the cell.
____2. Which of the following events is the first to occur during an action potential?
A. Sodium channels open.
B. Sodium channels close.
C. Potassium channels open.
D. Potassium ions flow out of the neuron.
E. Sodium ions flow into the neuron, making the inside of the neuron positively charged relative to the outside.
____3. Sodium-potassium pumps
A. do not require energy from ATP.
B. move only sodium ions into the cell.
C. move both sodium and potassium ions into the cell.
D. are open all the time, allowing potassium ions to leave the cell.
E. restore the distribution of ions inside and outside a neuron's membrane following an action potential.
____4. During an action potential
A. potassium ions move into the neuron.
B. potassium channels open first, followed by sodium channels.
C. sodium ions move into the neuron, then potassium ions move in.
D. the inside of the neuron becomes positively charged relative to the outside.
E. the inside of the neuron becomes negatively charged relative to the outside.
____5. What causes an action potential to be conducted along a neuron's axon?
A. The axon returns to its resting potential.
B. The change in charge difference across the membrane spreads from open sodium channels, causing sodium
channels farther along the axon to open.
C. The change in charge difference across the membrane spreads from open potassium channels, causing
sodium channels farther along the axon to open.
D. The change in charge difference across the membrane spreads from open potassium channels, causing
potassium channels farther along the axon to open.
E. The change in charge difference across the membrane spreads from open sodium channels, causing the
sodium-potassium pumps to move ions across the neuron's membrane.
AP Biology
Name: ____________________
BioFlix Study Sheet for How Synapses Work
Refer to your book, BioFlix Animation, and BioFlix Tutorials if you need help.
1. Draw a Synapse - In your drawing, be sure to show the sending neuron, synaptic terminal, receiving
neuron, synaptic cleft, calcium channels, vesicles, neurotransmitter molecules, and receptors for
neurotransmitter. Then describe the role of each structure in the table below.
Synapse Structure
Sending neuron
Synaptic terminal
Receiving neuron
Synaptic cleft
Calcium channel
Vesicle
Neurotransmitter
Receptors for
neurotransmitter
Role in How Synapses Work
2. How does information from many different synapses determine whether a receiving neuron generates an
action potential?
AP Biology
BioFlix Quiz – How Synapses Work
Write the answer to each question in the blank. Note that the order of the answer options does not match
the online version of the quiz.
____1. The small space between the sending neuron and the receiving neuron is the
A. vesicle.
B. synaptic cleft.
C. calcium channel.
D. neurotransmitter.
E. synaptic terminal.
____2. A molecule that carries information across a synaptic cleft is a
A. synapse.
B. synaptic cleft.
C. sending neuron.
D. receiving neuron.
E. neurotransmitter.
____3. When calcium ions enter the synaptic terminal,
A. they cause an action potential in the sending neuron.
B. the inside of the receiving neuron becomes more positive.
C. the inside of the receiving neuron becomes more negative.
D. neurotransmitter molecules are quickly removed from the synaptic cleft.
E. they cause vesicles containing neurotransmitter molecules to fuse to the plasma membrane of
the sending neuron.
____4. When neurotransmitter molecules bind to receptors in the plasma membrane of the receiving
neuron,
A. the receiving neuron becomes more positive inside.
B. the receiving neuron becomes more negative inside.
C. ion channels in the plasma membrane of the sending neuron open.
D. ion channels in the plasma membrane of the receiving neuron open.
E. vesicles in the synaptic terminal fuse to the plasma membrane of the sending neuron.
____5. If a signal from a sending neuron makes the receiving neuron more negative inside,
A. the sending neuron becomes more positive inside.
B. the sending neuron becomes more negative inside.
C. the receiving neuron immediately generates an action potential.
D. the receiving neuron is less likely to generate an action potential.
E. the receiving neuron is more likely to generate an action potential.
AP Biology
Name: ____________________
BioFlix Study Sheet for Muscle Contraction
Refer to your book, BioFlix Animation, and BioFlix Tutorials if you need help.
Part I: Muscle Structure - Draw or describe each of the structures below and state its role in muscle
contraction.
Structure
Motor neuron
Muscle fiber (cell)
Myofibril
Sarcomere
Myosin
Actin
Endoplasmic
reticulum
Calcium ions
ATP
Drawing or Description
Role
Part II: Muscle Contraction - For each of the following events in muscle contraction, draw actin, myosin,
and other relevant molecules and ions. Describe the events in your own words, adding more details where
appropriate.
Event
Muscle is relaxed.
Action potential
causes release of
calcium ions from
endoplasmic
reticulum.
Myosin head binds
to actin.
Power stroke –
myosin head pulls
the actin filament.
ATP binds to
myosin head.
Myosin head is
released from
actin.
ATP is broken down
and the myosin
head extends.
Drawing
Description of Events
AP Biology
BioFlix Quiz – Muscle Contraction
Write the answer to each question in the blank. Note that the order of the answer options does not match
the online version of the quiz.
____1. A muscle cell contains bundles of long
A. myofibrils.
B. sarcomeres.
C. calcium ions.
D. muscle fibers.
E. action potentials.
____2. When a sarcomere contracts
A. no ATP is required.
B. calcium ions bind to myosin.
C. actin heads bind to and pull myosin.
D. the actin and myosin filaments do not change in length.
E. the myosin-binding sites on actin are blocked by another protein.
____3. Which of the following events is the direct result of an action potential in the membrane of a muscle
cell?
A. The muscle relaxes.
B. The myosin head extends.
C. The myosin head detaches from actin.
D. Calcium ions are pumped into the endoplasmic reticulum (ER).
E. The muscle cell’s endoplasmic reticulum (ER) releases calcium ions.
____4. When ATP attaches to a myosin head,
A. the muscle relaxes.
B. the myosin head extends.
C. the myosin head detaches from actin.
D. calcium ions are released from the endoplasmic reticulum.
E. the myosin head pulls the actin filament, shortening the sarcomere.
____5. Calcium ions
A. bind to ATP.
B. bind to actin.
C. are released by the motor neuron.
D. bind to the protein that blocks the myosin-binding sites on actin.
E. are pumped into the endoplasmic reticulum (ER) during an action potential.