Biology

POSSIBLE WASSCE QUESTIONS ON CONTROL AND COORDINATION- (NERVOUS SYSTEM)

POSSIBLE WASSCE QUESTIONS ON CONTROL AND COORDINATION
(NERVOUS SYSTEM)

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1. What is a ganglion?

Ans: A ganglion is a cluster of neurons (nerve cell) bodies. In animals with a CNS and a
PNS, it is a cluster of neurons located outside the CNS.

What is the advantage for an animal having cephalization in addition to bilateral
symmetry?

Ans: Bilateral symmetry plus cephalization leads to paired sensory organs for sight,
hearing, and smell, that are useful for obtaining information about the animals
environmental.

2. Distinguish between the CNS and the PNS.

Ans: The CNS (central nervous system) consists of the brain and spinal cord while the
PNS (peripheral nervous system) is composed of nerves and ganglia.

3. Would a nerve impulse travel more quickly down an unmyelinated axon or a
myelinated axon? Why?

Ans: The nerve impulse would travel more quickly down the myelinated axon due to
saltatory conduction.

4. A nerve impulse has two parts. a. During the first part, which ion moves where? b.
During the second part, which ion moves where?

Ans: a. Na+ moves from the outside of the axon membrane to the inside.
b. K+ moves from the inside of the axon membrane to the outside.

6. How are neurotransmitter molecules removed from synaptic clefts?

Ans: Neurotransmitter molecules may be degraded by enzymes, or be taken up by the
presynaptic cell.

7. The brain is very dependent on the spinal cord. Explain.

Ans: The spinal cord contains important pathways for communication between the brain and
the spinal nerves which serve the rest of the body.

8. The hypothalamus, which has sleep centers, communicates with the RAS. What might
cause narcolepsy, the disorder characterized by brief periods of unexpected sleep?

Ans: Output from the RAS functions keeps us awake. A malfunctioning RAS may stop
signaling to the sleep centers in the hypothalamus, enabling them to temporarily take over
and cause uncontrollable sleepiness.

9. Brain injury can cause a disconnect between the amygdala and the portion of the
cortex devoted to recognizing faces. People with this ailment can identify the faces of family
members, but have no feelings for them. This is so disturbing that sufferers come to believe
their “real” families have been replaced with “imposters.” Explain.

Ans: We normally experience positive feelings when we recognize the familiar faces of our
loved ones. A disconnect between the amygdala and the cortex disables this emotional
response, and the injured person, desperate for an explanation, adopts the “imposter” belief.

10. What are two ways in which cranial nerves and spinal nerves differ from one
another?

Ans: Cranial nerves emerge from the brain; some are sensory, some are motor, and others are
mixed. Spinal nerves emerge from the spinal cord; all are mixed.

11. What part of the CNS is active when a reflex action involving the limbs occurs? b.
What part of the CNS is active when we override a reflex action and do not react
automatically?

Ans: a. The spinal cord; b. The brain.

12. You are sitting quietly, enjoying a slice of pizza and a soft drink. Your mischievous
best friend sneaks up behind you, then dumps ice down the back of your shirt. Describe the
shift in autonomic system activity that ensues.

Ans: The parasympathetic (“rest and digest”) division dominates as you enjoy your meal, but
your friend’s “surprise” causes a sudden increase in sympathetic (“fight or flight”) activity.

 

  • In individuals with panic disorder, the fight-or-flight response is activated by inappropriate stimuli. How might it be possible to directly control this response in order to treat panic disorder? Why is such control often impractical?

Ans: The most direct cause of the fight-or- flight response is norepinephrine released by the sympathetic nervous system.

If norepinephrine is being released inappropriately it could be that the postganglionic fibres are being triggered unnecessarily.

If so, control could be attempted by blocking production of norepinephrine or interaction of norepinephrine with its receptor.

However, the harm caused by disabling the sympathetic nervous system would probably outweigh the benefit of reducing the panic response.

 

  • A man who lost his leg several years ago continues to experience pain as though it were coming from the missing limb. What hypothesis could explain the neurological basis of this pain?

Ans: The portion of the brain’s somatosensory cortex originally devoted to sensation from an amputated limb gradually reorganizes itself; as a result, sensory input from different areas of the body is often perceived as pain in the missing limb.

In addition, some portion of the sensory neurons serving the amputated leg will still be present.

The axon portion of these neurons in the spinal cord would still be able to release neurotransmitter substances.

The release of neurotransmitter by sensory neurons coming from an amputated limb is being perceived as pain by the brain.

 

  • The density of taste buds on the tongue can vary. Some obese individuals have a lower density of taste buds than usual. Assume that taste perception is related to taste bud density. If so, what hypothesis would you test to see if there is a relationship between taste bud density and obesity?

Ans: Taste perception in the brain may be less in obese individuals with low density of taste buds. Measuring eating- associated brain activity may indicate taste perception.

Hypothesis: If low density of taste buds causes obesity, then brain activity associated with taste perception would be less in obese individuals compared to those who are not obese.

While quantity of taste perception may be related to obesity, many other factors may also be involved because eating must have various levels of control.

 

 

  • A man who has spent many years serving on submarines complains of hearing loss, particularly the inability to hear high tones. When a submarine submerges, the inside air pressure intensifies. What hypothesis or hypotheses might explain hearing loss in this individual?

Ans: Perhaps the increased air pressure upon submersion intensifies volume (loudness) leading to hearing loss.

Hypothesis 1: If increased air pressure causes hearing loss, then hair cells of the organ of Corti will be damaged in individuals subjected to increased air pressure.

Hypothesis 2: If increased air pressure causes the inability to hear high tones, then the organ of Corti at the base of the cochlea will show the greatest damage.

  • What are possible treatments for patients with major depression?

Ans: To determine the function of a specific brain area, scientists can look at patients who have damage in that brain area and see what symptoms they exhibit.

Researchers can disable the brain structure temporarily using transcranial magnetic stimulation.

They can disable or remove the area in an animal model. fMRI can be used to correlate specific functions with increased blood flow to brain regions.

  • What methods can be used to determine the function of a particular brain region?

Ans: Possible treatments for patients with major depression include psychotherapy and prescription medications.

MAO inhibitor drugs inhibit the breakdown of certain neurotransmitters (including dopamine, serotonin, norepinephrine) in the synaptic cleft.

SSRI medications inhibit the reuptake of serotonin into the presynaptic neuron.

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