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IB Biology HL, Year II
Option E: Neurobiology and Behaviour ~ Review
E.1. Stimulus and Response:
E.1.1 – Define stimulus, response, and reflex. For this objective, your goal is to be able to
discuss and think of examples, rather than simply to be able to state a definition.
What is an example of a cranial reflex? _____________________________________
What is an example of a spinal reflex? ______________________________________
E.1.2 – How are receptors, sensory neurons, relay neurons, motor neurons, synapses, and
effectors (the muscles or other organs involved in producing the response) involved in
animals’ responses to stimuli? Thinking about the monosynaptic reflex arc involved in the
knee jerk reflex could be helpful. This is something that you should also know for the
upcoming unit on Muscles and Movement, so learning it now is a good idea!
Practice drawing the reflex arc for the knee jerk reflex, including the spinal cord. Include
the receptors, sensory neurons, relay neurons, motor neurons, synapses, effectors, and
parts of the spinal cord (dorsal root, gray matter, ventral root) involved.
E.1.3 – Draw and label a reflex arc for a pain withdrawal reflex.
E.1.4 – Explain how animal responses can be affected by natural selection, using two
examples. You may want to re-read the examples in the book – keep in mind that there
should be a clear inherited/ genetic component (p.462-464).
E.2. Perception of Stimuli
E.2.1 – Be able to identify the different types of sensory receptors. When you’re asked a
question about this, they’re generally looking for the major classes of receptors, not
specific receptors like rods/ cones or hair cells. Be sure to read the question carefully.
Mechanical
Light
Chemical
Temperature
Formal Name
Examples of
roles in the
body
Specific
examples (if we
discussed
them)
E.2.2 – Diagram and label the human eye. Remember what you saw in the sheep eye
dissection, and see p. 466 for a sample diagram and summary table.
E.2.3 – Diagram the retina and show the direction in which light moves.
Bonus! Which is a rod cell and which is a cone?
Also, be cautious about what the line is pointing to in I!
E.2.4 – Compare rod and cone cells.
Feature
Rods
Good or Poor Visual
Acuity?
Night vision vs. Day vision?
Cones
Location along retina?
(fovea or periphery?)
3 colors of pigment vs. one
type of pigment?
One-to-one convergence
vs. multiple converging on
ganglion cells
Rod shaped vs. cone
shaped
Sensitive to all wavelengths
equally (so cannot
distinguish color well) vs.
sensitive to red, blue and
green colors of light
How would you process perception of the color blue, starting in the retina and going to the
brain?
E.2.5 – Cells in the retina, especially the rod cells, are extremely important in processing
edge detection. Read the section on “Edge Enhancement” (p. 468-469) for a review of how
this works. Remember also that there is a variation of contralateral processing in vision.
Can you draw your own version of this diagram from memory? AND describe it?
E.2.6 – Draw and label a diagram of the ear.
E.2.7 – Explain how sound is perceived by the ear, including roles of the eardrum, bones
of the inner ear (malleus, incus, stapes), oval and round windows, and the hair cells. (In
other words, be able to annotate the diagram that you just labeled.)
E.3. Innate and Learned Behavior
E.3.1 – Distinguish between innate and learned behavior – not always as simple to do as it
may seem!
Define innate behavior.
Provide an example of learned behavior.
How do we know that something is learned behavior?
Provide some examples of innate behavior.
E.3.2 – Design experiments to investigate innate behavior in invertebrates, including either
a taxis or kinesis.
A taxis is ____________________________________________________________,
such that a ______________________ taxis response would be movement toward the
stimulus (e.g. pillbugs moving away from a light source is a _____________________
phototaxic response). A kinesis is a behavioral response to a non-directional stimulus; for
example, if animals exhibit less movement in hotter temperatures, this would be a kinesis.
In other words, kineses depend on the intensity of the stimulus, rather than its location.
E.3.3 – Analyze data! Guess what kind of question this will lend itself to… You should
practice from the examples at the end of the chapter to get an idea of the type of DBQs
that may be asked.
E.3.4 – Discuss how learning can improve survival. There are a lot of examples – make
sure that you provide one that actually discusses a named type of learning (e.g. classical
conditioning, imprinting, etc.)
E.3.5 – Outline classical conditioning. Explain what’s being depicted below:
UCS  UCR
CS + UCS  UCR
After repeated pairings: CS  CR
Who was Pavlov? What species did he experiment with?
E.3.6 – Outline the role of inheritance and learning in the development of birdsong. This
was the notion that there are templates for behavior that can be guided by exposure;
different species of birds are capable of producing a fixed variety of songs, but will
generally learn to memorize and match the songs that they are exposed to as young birds.
What evidence is there for an element of learning in the development of birdsong?
E.4. Neurotransmitters and Receptors
E.4.1 – Understand the concepts of excitatory and inhibitory signals. Excitatory signals
generate action potentials in the post-synaptic neuron, while inhibitory signals prevent
these action potentials from firing. Excitatory and inhibitory impulses are important in pain
withdrawal reflexes (e.g. the arm is flexed away from the painful stimulus when excitatory
signals contract the flexor muscles and inhibitory signals force relaxation of extensor
muscles). They are also important in the actions of various drugs (e.g. alcohol involves
down-regulation of the excitatory neurotransmitter glutamate while up-regulating the
inhibitory neurotransmitter GABA).
Neurotransmitters are released by (presynaptic / postsynaptic) neurons. They diffuse
across the __________________ and bind to ____________________ on the
(presynaptic / postsynaptic)neuron.
Some neurotransmitters increase the permeability of postsynaptic neurons to positive ions,
causing depolarization. These are (inhibitory / excitatory) synapses. They will cause a(n)
_________________________ to fire if the membrane potential is raised above a
threshold.
Other neurotransmitters cause negatively charged chloride ions to move into the cell, or K +
ions to move out of the postsynaptic cell. This leads to ___________________________
of the postsynaptic cell, decreasing the chance that an action potential to fire. Such
synapses are (inhibitory / excitatory).
Name an example of an excitatory neurotransmitter: ___________________________
Name an example of an inhibitory neurotransmitter: ___________________________
E.4.2 – Explain how decision making in the CNS can result from the interaction of
excitatory and inhibitory pre-synaptic neurons. In other words, the summation of the
excitatory and inhibitory signals going to a neuron will determine whether a threshold of
depolarization is met to allow an action potential to fire.
E.4.3 – Explain how psychoactive drugs affect the brain by either increasing or decreasing
post-synaptic activity. In other words, psychoactive drugs take advantage of these
inhibitory and excitatory signals to either activate or inactivate neurons.
* Even though not explicitly stated in any objectives, you should know how the inhibitory
and excitatory drugs listed below work. You should also be familiar with their general
behavioral/ cognitive effects (do they activate behavior? cause feelings of reward?
decrease memory?). Review the worksheet that was given on Drugs and Receptors. You
don’t need to know all 6, but cocaine, THC, and then one additional excitatory and one
additional inhibitory would be a good guideline.
E.4.4 – List 3 examples of excitatory and inhibitory drugs.

Excitatory: ________________________________________________

Inhibitory: ________________________________________________
E.4.5 – Explain the effects of THC and cocaine.
THC mimics ____________________, an endogenous (internal) cannabinoid. THC binds
to cannabinoid receptors and shuts off inhibition of dopamine release, providing a
pleasurable sensation. At the same time, the activation of cannabinoid receptors is
involved in inhibition of motor activity, decreased posture and balance, and inhibited
activity in areas associated with memory and learning.
Cocaine acts by blocking _________________ of ________________, causing this
rewarding neurotransmitter to stay in the synapse for a much longer period of time. This
results in hyperactivity and euphoria.
E.4.6 – Discuss the causes of addiction, including genetic predisposition, social factors,
and dopamine secretion. The section on p. 487-488 reviews this nicely.
E.5. The Human Brain
E.5.1 – The objective asks for you to label various parts of the brain.
I.
.............................
II. .............................
III. .............................
IV. .............................
V.
.............................
E.5.2 – Annotate the parts of the brain shown above.
E.5.3 – Explain how animal experiments, lesion studies, and fMRI scanning can help us
learn about the functions of different brain areas. To review, you may wish to review p.
491-494 and the notes from these lessons. I discussed some things that weren’t explicitly
written in the powerpoint slides, so please ask if you’re unclear on anything.
E.5.4 – Understand the roles of the sympathetic and parasympathetic nervous systems.
This seems to be a favorite topic in the IB program…
What are the effects of the autonomic nervous system on:
Factor
Heart beat?
Saliva production/
digestion?
Pupil dilation?
Excitatory or Inhibitory
Actions?
What neurotransmitter is
associated with it?
Sympathetic
Parasympathetic
E.5.5 – Explain the pupil reflex. Some things to remember:
1) This is a (cranial / spinal) reflex, unlike pain withdrawal and the knee jerk reflex,
which are (cranial / spinal) reflexes.
2) Can be used as part of a test for brain death.
3) When the eye is exposed to light, the radial iris muscle ________________ and the
pupils ______________. When the eye is in darkness, the radial iris muscle
____________ and the pupils _____________.
4) The sympathetic nervous system (generally activating) is involved in pupil
___________________ (think about the radial iris muscles contracting) while the
parasympathetic nervous system (generally relaxing) is involved in pupil
_____________________.
E.6.6 – Brain death is “that time when a physician(s) has determined that the brain and
brain stem have irreversibly lost all neurological function”. The pupil reflex, along with other
tests, is useful because it is a cranial reflex rather than a spinal reflex. Some spinal
reflexes, such as the knee jerk reflex, may still be active during brain death because they
do not rely on brain activity.
E.6.7 – Pain is perceived via ___________________________, which can sense extreme
pain, pressure, or chemicals (both exogenous chemicals and chemical signals produced
by the body). These specialized receptors often consist of free nerve endings in the skin.
When pain signals reach the central nervous system and brain, neurotransmitters called
__________________________ are released. These are the body’s natural painkillers.
They can act directly at the site of injury or in areas of the brain associated with pain
perception to block transmission of pain signals.
E.6. Further Studies of Behaviour
Please review the packet on “Studies of Behavior”. If you want a clean copy, you can get
one from the blog for extra practice.