BIOL 455 neurobiology exams 1,2,3 Questions and Answers Already Passed Latest Update
2025-2026
Exam 1 - Answers Exam 1
All vertebrate brains are characterized by a forebrain, midbrain, and hindbrain because of -
Answers Common developmental origins
Which of the following structures is found in the diencephalon? - Answers Hypothalamus;
thalamus
The forebrain is made up of which two main division? - Answers telencephalon;
diencephalon
Centralized nervous systems have evolved multiple times independently in animals. What
selective pressure(s) were the likely cause? (~2-3 sentences) - Answers Selection for short
axons results in centralization b/c neurons have to be close together
Short axons are selected for b/c they are more energetically efficient (and result in faster
communication between neurons)
Describe the specific behavioral deficit you would predict from a lesion of the superior colliculus.
(~1-2 sentences) - Answers An individual with a lesion of the superior colliculus would have
difficulty localizing and/or orienting to visual stimuli in space. Visual awareness would be intact.
An person develops a tumor in her hypothalamus. It was successfully removed without
significant damage to surrounding tissues. Which of the following are likely consequences of
her surgery? - Answers Persistent thirst; Lack of sex drive
Why is topography so common in nervous systems? (~2 sentences) - Answers Topography
ensures that neighboring neurons are processing similar information.
Topography allows overall axon length to be shorter.
The peripheral auditory system is organized so that different cells respond to different tones
(sound frequencies). Draw a figure that shows topographic projection patterns between two
brain regions for the following tones: 1000 Hz, 2000 3000 Hz, and 4000 Hz. - Answers
Topographic projections illustrated
Pathways labeled
What is the primary conclusion you can draw from the figure above? (1-2 sentences) - Answers
Centralized nervous systems evolved multiple times independently in animals.
Why does brain size scale with body size? (2-4 sentences) - Answers Larger bodies require
more neurons to innervate them (e.g., greater sensory surface, more muscles).
, The theory of mosaic evolution posits that - Answers The relative size of different brain regions
can evolve independently of one another.
Based on information in the figure above, we conclude that mosaic evolution likely explains the
relatively large size of the superior colliculus (SC) in ground squirrels because - Answers The
size of the SC in ground squirrels cannot be predicted from overall brain size.
Finlay and colleagues have argued that brain regions tend to evolve in concert with one another
because - Answers They are constrained to do so by the rules of neural development.
Which of the above figures is most consistent with Concerted Evolution leading to a larger
hippocampus in caching birds? - Answers B
Explain the rationale you used to select your answer - Answers Figure B shows that
hippocampal volume can be predicted from whole brain volume which is the central prediction
of concerted evolution.
Based on the figure above, we can conclude that the number of neurons in the neocortex of
humans - Answers Is predicted from scaling rules in primates
Which of the following is a primary constraint on the evolution of relative brain size in primates?
- Answers Diet
The resting membrane potential is closest to the equilibrium potential of potassium (K+)
because - Answers The cell membrane is more permeable to potassium than other ions.
A new drug is found to lower the threshold for voltage-gated potassium (K+) channels. What
would be the consequence for the electrical activity of a neuron exposed to this drug? - Answers
Action potentials of shorter duration
Based on what you know about channels and action potentials, design a drug to reduce the
probability of seizures. How does your drug work? (4 sentences) - Answers Drug acts in
plausible way to change excitability of neurons..
Mechanism of drug action is explained
Myelination results in a significant increase in conduction velocity of vertebrate axons by -
Answers Decreasing the capacitance of the membrane
Increasing the length constant
In the neuron in the figure above, the + and - symbols represent synapses that are excitatory or
inhibitory, respectively. All synapses have the same efficacy, meaning that they evoke the same
absolute change in postsynaptic potential. Synapse 2 is more likely to evoke an action potential
than synapse 4. Why? (2-3 sentences) - Answers Synapse 2 is closer to the axon hillock where
the voltage-gated sodium channels can initiate an action potential.
2025-2026
Exam 1 - Answers Exam 1
All vertebrate brains are characterized by a forebrain, midbrain, and hindbrain because of -
Answers Common developmental origins
Which of the following structures is found in the diencephalon? - Answers Hypothalamus;
thalamus
The forebrain is made up of which two main division? - Answers telencephalon;
diencephalon
Centralized nervous systems have evolved multiple times independently in animals. What
selective pressure(s) were the likely cause? (~2-3 sentences) - Answers Selection for short
axons results in centralization b/c neurons have to be close together
Short axons are selected for b/c they are more energetically efficient (and result in faster
communication between neurons)
Describe the specific behavioral deficit you would predict from a lesion of the superior colliculus.
(~1-2 sentences) - Answers An individual with a lesion of the superior colliculus would have
difficulty localizing and/or orienting to visual stimuli in space. Visual awareness would be intact.
An person develops a tumor in her hypothalamus. It was successfully removed without
significant damage to surrounding tissues. Which of the following are likely consequences of
her surgery? - Answers Persistent thirst; Lack of sex drive
Why is topography so common in nervous systems? (~2 sentences) - Answers Topography
ensures that neighboring neurons are processing similar information.
Topography allows overall axon length to be shorter.
The peripheral auditory system is organized so that different cells respond to different tones
(sound frequencies). Draw a figure that shows topographic projection patterns between two
brain regions for the following tones: 1000 Hz, 2000 3000 Hz, and 4000 Hz. - Answers
Topographic projections illustrated
Pathways labeled
What is the primary conclusion you can draw from the figure above? (1-2 sentences) - Answers
Centralized nervous systems evolved multiple times independently in animals.
Why does brain size scale with body size? (2-4 sentences) - Answers Larger bodies require
more neurons to innervate them (e.g., greater sensory surface, more muscles).
, The theory of mosaic evolution posits that - Answers The relative size of different brain regions
can evolve independently of one another.
Based on information in the figure above, we conclude that mosaic evolution likely explains the
relatively large size of the superior colliculus (SC) in ground squirrels because - Answers The
size of the SC in ground squirrels cannot be predicted from overall brain size.
Finlay and colleagues have argued that brain regions tend to evolve in concert with one another
because - Answers They are constrained to do so by the rules of neural development.
Which of the above figures is most consistent with Concerted Evolution leading to a larger
hippocampus in caching birds? - Answers B
Explain the rationale you used to select your answer - Answers Figure B shows that
hippocampal volume can be predicted from whole brain volume which is the central prediction
of concerted evolution.
Based on the figure above, we can conclude that the number of neurons in the neocortex of
humans - Answers Is predicted from scaling rules in primates
Which of the following is a primary constraint on the evolution of relative brain size in primates?
- Answers Diet
The resting membrane potential is closest to the equilibrium potential of potassium (K+)
because - Answers The cell membrane is more permeable to potassium than other ions.
A new drug is found to lower the threshold for voltage-gated potassium (K+) channels. What
would be the consequence for the electrical activity of a neuron exposed to this drug? - Answers
Action potentials of shorter duration
Based on what you know about channels and action potentials, design a drug to reduce the
probability of seizures. How does your drug work? (4 sentences) - Answers Drug acts in
plausible way to change excitability of neurons..
Mechanism of drug action is explained
Myelination results in a significant increase in conduction velocity of vertebrate axons by -
Answers Decreasing the capacitance of the membrane
Increasing the length constant
In the neuron in the figure above, the + and - symbols represent synapses that are excitatory or
inhibitory, respectively. All synapses have the same efficacy, meaning that they evoke the same
absolute change in postsynaptic potential. Synapse 2 is more likely to evoke an action potential
than synapse 4. Why? (2-3 sentences) - Answers Synapse 2 is closer to the axon hillock where
the voltage-gated sodium channels can initiate an action potential.
