Bio 7

Question 1

Which type of muscle controls the movement of internal organs like the digestive system?
A) Skeletal muscle
B) Smooth muscle
C) Cardiac muscle
D) Striated muscle

Answer 1

Answer: B) Smooth muscle
Explanation: Smooth muscles operate involuntarily and manage systems like digestio

Question 2

At a neuromuscular junction in skeletal muscles, the neurotransmitter released is:
A) Dopamine
B) Serotonin
C) Acetylcholine
D) GABA

Answer 2

Answer: C) Acetylcholine
Explanation: Acetylcholine is always released to cause muscle contraction at skeletal neuromuscular junctions.

Question 3

Why does an eye muscle have a lower axon-to-fiber ratio than a biceps muscle?
A) Eye muscles require stronger force
B) Eye muscles require more precise movement
C) Biceps muscles require faster responses
D) Biceps muscles require more endurance

Answer 3

Answer: B) Eye muscles require more precise movement
Explanation: Fewer fibers per axon allow finer control needed for eye movements.

Question 4

What happens when a skeletal muscle receives no message from a neuron?
A) It contracts partially
B) It relaxes
C) It enters anaerobic metabolism
D) It switches to using white muscle fibers

Answer 4

Answer: B) It relaxes
Explanation: Skeletal muscles only contract with stimulation; otherwise, they passively relax.

Question 5

Flexor muscles are responsible for:
A) Extending a limb away from the body
B) Contracting the heart muscles
C) Bringing a limb closer to the body
D) Maintaining balance

Answer 5

Answer: C) Bringing a limb closer to the body
Explanation: Flexor muscles like the biceps bring parts of the body toward each other.

Question 6

Which characteristic describes white muscles in fish?
A) Slow movement, no fatigue
B) Fast movement, rapid fatigue
C) Moderate speed, moderate fatigue
D) Fast movement, no fatigue

Answer 6

Answer: B) Fast movement, rapid fatigue
Explanation: White muscles are quick but tire very quickly.

Question 7

Human slow-twitch muscle fibers are described as:
A) Anaerobic and fast-fatiguing
B) Aerobic and fatigue-resistant
C) Anaerobic and slow-moving
D) Aerobic and fast-fatiguing

Answer 7

Answer: B) Aerobic and fatigue-resistant
Explanation: Slow-twitch fibers use oxygen efficiently and resist fatigue, perfect for enduranc

Question 8

Why do fast-twitch fibers fatigue quickly?
A) They use aerobic metabolism
B) They rely on constant oxygen supply
C) They use anaerobic processes creating oxygen debt
D) They break down lactic acid slowly

Answer 8

Answer: C) They use anaerobic processes creating oxygen debt
Explanation: Fast-twitch fibers don’t use oxygen during contraction, building up a need for later oxygen (oxygen debt).

Question 9

During prolonged bicycling, what shift occurs in muscle fiber usage?
A) Slow-twitch to fast-twitch reliance
B) Fast-twitch to slow-twitch reliance
C) Increased reliance on cardiac muscles
D) Complete reliance on red muscle fibers

Answer 9

Answer: A) Slow-twitch to fast-twitch reliance
Explanation: As glucose depletes, muscles switch to fast-twitch fibers relying on anaerobic metabolism.

Question 10

Competitive sprinters are more likely to have:
A) Greater amounts of slow-twitch fibers
B) Greater amounts of fast-twitch fibers
C) Equal fast- and slow-twitch fibers
D) Greater numbers of pink muscles

Answer 10

Answer: B) Greater amounts of fast-twitch fibers
Explanation: Sprinters need explosive speed, relying heavily on fast-twitch fibers.

Question 11

Which of the following best describes the function of muscle spindles?
A) They detect muscle tension and inhibit contraction.
B) They detect muscle stretch and initiate reflexive contraction.
C) They detect tendon strain and promote muscle relaxation.
D) They provide conscious proprioceptive sensation to the brain.

Answer 11

Answer: B
Explanation: Muscle spindles respond to muscle stretch by triggering reflexive contraction to oppose the stretch (negative feedback).

Question 12

The knee-jerk reflex primarily tests the function of which structure?
A) Golgi tendon organ
B) Muscle spindle
C) Central pattern generator
D) Motor cortex

Answer 12

Answer: B
Explanation: The tap stretches the extensor muscles and their spindles, causing a reflexive contraction that jerks the leg upward.

Question 13

The Golgi tendon organ is crucial for preventing:
A) Muscle fatigue during sustained activity.
B) Overstretching of muscles.
C) Excessively strong muscle contractions that could cause damage.
D) Loss of proprioceptive feedback during movement.

Answer 13

Answer: C
Explanation: Golgi tendon organs inhibit further contraction when tension is too high, acting as a “brake” to prevent muscle damage.

Question 14

Which outcome would most likely result from a loss of Golgi tendon organ function?
A) Muscle stiffness during movement.
B) Inability to detect changes in muscle length.
C) Increased risk of muscle or tendon rupture due to excessive contraction.
D) Failure of the stretch reflex.

Answer 14

Answer: C
Explanation: Without Golgi tendon inhibition, muscles could contract too strongly, leading to damage.

Question 15

Which phenomenon best illustrates proprioceptors’ role in adjusting expectations based on visual input?
A) Stretch reflex after a sudden tap.
B) Perceived heaviness of a small, dense object.
C) Automatic arm swinging during walking.
D) Ballistic movement of kicking a ball.

Answer 15

Answer: B
Explanation: The mismatch between expected and actual proprioceptive feedback causes the small object to feel heavier.

Question 16

Which of the following is an example of a ballistic movement?
A) Threading a needle.
B) Yawning.
C) Playing a piano piece with constant adjustments.
D) Adjusting posture after tripping on uneven ground.

Answer 16

Answer: B
Explanation: A ballistic movement, like yawning, once initiated, proceeds without further adjustment.

Question 17

Central pattern generators are primarily responsible for:
A) Reflexive inhibition of muscle tension.
B) Adjustments in voluntary movements based on feedback.
C) Producing rhythmic motor patterns independently of sensory input.
D) Conscious planning of complex motor sequences.

Answer 17

Answer: C
Explanation: Central pattern generators produce automatic, rhythmic activities like walking or scratching without constant brain input.

Question 18

In what way is walking both voluntary and involuntary?
A) All movements during walking are entirely conscious decisions.
B) Walking consists entirely of reflexive responses without planning.
C) Walking involves voluntary initiation but involuntary reflex adjustments to the environment.
D) Walking is a purely ballistic movement controlled by the spinal cord

Answer 18

Answer: C
Explanation: You choose to walk (voluntary), but reflexes like knee-jerk responses automatically adjust steps to bumps and irregularities.

Question 19

Which experimental finding supports the idea that motor programs can persist despite loss of functional utility?
A) Yawning persists across different human cultures.
B) Ostriches flap their wings when dropped.
C) Chickens with featherless wings still flap when falling.
D) Reflexive foot motion reverses when hand movement is changed.

Answer 19

Answer: C
Explanation: Chickens still exhibit wing-flapping motor programs even if their wings can’t actually help them fly.

Question 20

Which statement best explains why primates, including humans, exhibit greater dexterity compared to most mammals?
A) They have a larger prefrontal cortex relative to body size.
B) Their motor cortex neurons connect directly to muscle fibers.
C) Their cerebral cortex sends direct projections to motor neurons.
D) Their spinal cord neurons are more specialized for fine motor control.

Answer 20

Answer: C
Explanation: In primates, some axons from the cerebral cortex project directly to motor neurons, bypassing interneurons, allowing for finer and more dexterous control.

Question 21

When stimulating a region of the motor cortex for a prolonged duration, researchers found:
A) Brief muscle twitches corresponding to individual muscles.
B) Random, uncoordinated muscle movements.
C) Complex, goal-directed movement patterns.
D) Complete inhibition of voluntary movements.

Answer 21

Answer: C
Explanation: Long stimulation (half a second) elicited complex coordinated behaviors, like a grasp-to-mouth movement, indicating the motor cortex orders outcomes, not individual muscles.

Question 22

Which brain area is essential for monitoring body position relative to the external world and shows increased activity during movement planning delays?
A) Prefrontal cortex
B) Premotor cortex
C) Posterior parietal cortex
D) Primary motor cortex

Answer 22

Answer: C
Explanation: The posterior parietal cortex monitors body position and becomes active during movement planning tasks, especially during delay periods.

Question 23

A person showers with clothes on and pours water on a toothpaste tube instead of a toothbrush. The most likely site of brain damage is:
A) Supplementary motor cortex
B) Premotor cortex
C) Posterior parietal cortex
D) Prefrontal cortex

Answer 23

Answer: D
Explanation: Prefrontal cortex damage leads to disorganized movements because it is crucial for predicting the outcomes of actions and planning appropriately.

Question 24

The antisaccade task mainly tests the functionality of which brain regions?
A) Primary motor cortex and somatosensory cortex
B) Prefrontal cortex and basal ganglia
C) Posterior parietal cortex and premotor cortex
D) Supplementary motor cortex and brainstem

Answer 24

Answer: B
Explanation: Prefrontal cortex and basal ganglia are necessary to inhibit reflexive saccades and perform the antisaccade (looking away from stimulus).

Question 25

Which statement about the relationship between the primary motor and somatosensory cortices is most accurate? A) They control entirely separate body parts. B) Motor cortex regions directly map to single muscles. C) Areas of control and sensation for body parts are spatially adjacent. D) Motor cortex is organized only according to the number of muscles involved.

Answer 25

Answer: C Explanation: The motor cortex and somatosensory cortex have adjacent and corresponding maps of the body, supporting coordinated movement and sensation.

Question 26

During an error in executing a movement, which brain area helps develop strategies to avoid repeating the same error? A) Prefrontal cortex B) Supplementary motor cortex C) Premotor cortex D) Primary motor cortex

Answer 26

Answer: B Explanation: The supplementary motor cortex becomes active after an error to help inhibit incorrect movements next time.

Question 27

Damage to which area would most likely result in difficulty resisting an impulse to immediately react to a moving object? A) Posterior parietal cortex B) Basal ganglia C) Prefrontal cortex D) Premotor cortex

Answer 27

Answer: C Explanation: The prefrontal cortex enables inhibition of reflexive actions; damage results in impulsivity, such as failing the antisaccade task.

Question 28

Which of the following best reflects the developmental trajectory of antisaccade task performance? A) Improves steadily from infancy and peaks in adolescence. B) Is fully developed by age 3. C) Peaks in early childhood and declines through adulthood. D) Remains constant across the lifespan.

Answer 28

Answer: A Explanation: Antisaccade performance gradually improves from early childhood, peaks in young adulthood, and declines in old age due to prefrontal cortex development and later deterioration.

Question 29

Which of the following best describes the crossing pattern of the lateral corticospinal tract? A) It crosses to the ipsilateral side at the medulla. B) It crosses to the contralateral side at the pyramids of the medulla. C) It crosses at the level of the spinal cord segment. D) It does not cross and remains on the same side throughout.

Answer 29

Answer: B) It crosses to the contralateral side at the pyramids of the medulla. Explanation: The lateral corticospinal tract crosses (decussates) at the pyramids of the medulla, allowing the left hemisphere to control muscles on the right side and vice versa.

Question 30

Damage to which structure would most severely affect fine motor control of the fingers on the right hand? A) Left medial corticospinal tract B) Right medial corticospinal tract C) Left lateral corticospinal tract D) Right lateral corticospinal tract

Answer 30

Answer: C) Left lateral corticospinal tract Explanation: Fine motor control (like that of the fingers) relies on the lateral corticospinal tract. Since the tract crosses, damage to the left hemisphere affects the right side.

Question 31

Which brain region directly contributes to both the medial and lateral corticospinal tracts? A) Red nucleus B) Primary motor cortex C) Vestibular nucleus D) Reticular formation

Answer 31

Answer: B) Primary motor cortex Explanation: The primary motor cortex contributes axons to both the lateral and medial corticospinal tracts, although the lateral tract is more directly associated with it.

Question 32

Which of the following statements about the medial corticospinal tract is TRUE? A) It mainly controls unilateral fine movements. B) It projects only to the contralateral side of the spinal cord. C) It is essential for bilateral movements like standing and bending. D) It originates primarily from the red nucleus.

Answer 32

Answer: C) It is essential for bilateral movements like standing and bending. Explanation: The medial tract controls muscles of the trunk and neck, crucial for bilateral actions that involve coordination of both sides of the body.

Question 33

Which source does NOT send axons through the medial corticospinal tract? A) Midbrain tectum B) Vestibular nucleus C) Red nucleus D) Reticular formation

Answer 33

Answer: C) Red nucleus Explanation: The red nucleus mainly contributes to the lateral corticospinal tract, not the medial one.

Question 34

Loss of which sensory system would most severely impair motor control by disrupting feedback necessary for movement? A) Visual B) Vestibular C) Somatosensory (touch) D) Auditory

Answer 34

Answer: C) Somatosensory (touch) Explanation: Touch feedback is essential for adjusting and coordinating movements — knowing what your hands (or other body parts) are doing is critical for planning the next move.

Question 35

Which of the following statements best describes the role of the cerebellum in motor control? a) The cerebellum controls voluntary motor movement, specifically continuous movements like walking and talking. b) The cerebellum is mainly responsible for balance and coordination, with a focus on static postural control. c) The cerebellum is crucial for precise timing, aim, and coordination of voluntary movements, but not for continuous actions like walking. d) The cerebellum is involved only in involuntary movements, with no role in voluntary actions such as typing or playing musical instruments.

Answer 35

Answer: c) Explanation: The cerebellum is vital for precise timing, aim, and coordination of voluntary movements, such as clapping, typing, or playing a musical instrument. It does not primarily control continuous movements like walking, which rely on different brain regions.

Question 36

What is the primary role of the Purkinje cells in the cerebellar cortex? a) They generate excitatory signals that stimulate the deep nuclei of the cerebellum. b) They transmit inhibitory messages to the deep nuclei of the cerebellum. c) They receive sensory input directly from the spinal cord and cranial nerve nuclei. d) They relay motor commands directly to the muscles.

Answer 36

Answer: b) Explanation: Purkinje cells in the cerebellar cortex send inhibitory signals to the deep nuclei of the cerebellum, which helps control the timing and coordination of motor output.

Question 37

What would most likely occur if a person suffered damage to the cerebellar cortex? a) They would experience difficulty with the timing and initiation of movements, such as tapping a rhythm or pointing at a moving object. b) They would experience complete loss of voluntary motor control, including the ability to walk or talk. c) They would lose the ability to recognize sensory stimuli, such as touch and temperature. d) They would become unable to perform continuous actions like walking or standing.

Answer 37

Answer: a) Explanation: Damage to the cerebellar cortex primarily impairs the timing and initiation of movements, such as tapping rhythms, pointing at moving objects, or speaking. It does not lead to the complete loss of voluntary motor control or continuous actions.

Question 38

In a functional MRI study, cerebellar activity would be most prominent during which of the following tasks? a) Lifting heavy objects b) Feeling and identifying objects with both hands c) Listening to loud sounds d) Completing a crossword puzzle

Answer 38

Answer: b) Explanation: The cerebellum is most active when performing tasks that involve precise sensory processing and timing, such as feeling and identifying objects with both hands. It shows minimal activity during simple physical tasks like lifting objects.

Question 39

A person with cerebellar damage might have difficulty performing which of the following tasks? a) Running on a treadmill b) Maintaining eye fixation and making accurate saccades (eye movements) c) Speaking at a normal pace d) Judging the loudness of a sound

Answer 39

Answer: b) Explanation: Cerebellar damage often impairs the ability to make precise eye movements (saccades), which require the cerebellum's input for accurate programming of the eye's angle and distance during voluntary shifts of fixation.

Question 40

Which of the following best explains why people with cerebellar damage might struggle with tasks requiring precise timing? a) The cerebellum's role in emotional regulation interferes with motor tasks. b) The cerebellum regulates the balance of sensory inputs, affecting spatial awareness. c) The cerebellum is critical for the perception and execution of movements that depend on precise timing intervals, such as rhythm or motor coordination. d) The cerebellum's role in muscle strength and power is compromised.

Answer 40

Answer: c) Explanation: The cerebellum is essential for the perception and execution of movements that depend on precise timing intervals, such as rhythmic tasks, accurate movement coordination, and timing the duration of sensory stimuli

Question 41

Which of the following best describes the main function of the basal ganglia in motor control? A) Selecting which movement to make B) Initiating spontaneous movements faster than stimulus-driven movements C) Regulating the vigor of movements and motivation D) Sending direct motor commands to muscles

Answer 41

Answer: C) Regulating the vigor of movements and motivation Explanation: Cells in the primary motor cortex activate before the basal ganglia, indicating the basal ganglia regulate how strongly a movement is made, not which movement is selected.

Question 42

The striatum, composed of the caudate nucleus and putamen, receives input from which of the following? A) Thalamus and cerebellum B) Cerebral cortex and substantia nigra C) Motor cortex and hippocampus D) Frontal cortex and amygdala

Answer 42

Answer: B) Cerebral cortex and substantia nigra Explanation: The striatum gets input mainly from the cerebral cortex and substantia nigra and sends output to the globus pallidus.

Question 43

Which best characterizes the direct pathway of the basal ganglia? A) It excites movement by inhibiting an inhibitor. B) It suppresses all voluntary movements. C) It prevents stimulus-driven behaviors. D) It coordinates automatic reflexes.

Answer 43

Answer: A) It excites movement by inhibiting an inhibitor. Explanation: The direct pathway inhibits the globus pallidus, which itself inhibits the thalamus, leading to a net excitation.

Question 44

Damage to the striatum would most likely impair a person's ability to: A) Feel physical pain B) Learn new motor habits and make vigorous spontaneous movements C) Understand verbal instructions D) React quickly to external stimuli

Answer 44

Answer: B) Learn new motor habits and make vigorous spontaneous movements Explanation: Striatal damage affects both the formation of new motor habits and the vigor of spontaneous, self-initiated actions.

Question 45

The indirect pathway of the basal ganglia is especially important for: A) Accelerating movement onset B) Suppressing inappropriate or competing movements C) Enhancing unplanned reflexes D) Directing eye movements

Answer 45

Answer: B) Suppressing inappropriate or competing movements Explanation: The indirect pathway inhibits competing actions, allowing for smoother and more appropriate movement execution.

Question 46

In motor learning, changes in the motor cortex during practice include: A) Randomization of neuronal firing to encourage flexibility B) Increase in the signal-to-noise ratio for more consistent movement patterns C) Decrease in firing rates to conserve energy D) Exclusive reliance on cerebellar adjustments

Answer 46

Answer: B) Increase in the signal-to-noise ratio for more consistent movement patterns Explanation: As movements become faster and more consistent, the motor cortex’s firing becomes more predictable and efficient.

Question 47

When comparing spontaneous versus stimulus-driven movements, spontaneous movements are generally: A) Faster due to basal ganglia priming B) Slower because they require internal decision-making C) Faster because they bypass cortical input D) Equally fast under normal conditions

Answer 47

Answer: B) Slower because they require internal decision-making Explanation: Spontaneous actions require more planning time internally, making them slower than stimulus-driven reactions.

Question 48

In the Western movie gunfight analogy, why could the hero draw second yet still win? A) Heroes have better reaction times. B) Stimulus-driven responses are naturally faster than self-initiated movements. C) Self-initiated movements are unpredictable. D) Basal ganglia output bypasses normal reflex pathways.

Answer 48

Answer: B) Stimulus-driven responses are naturally faster than self-initiated movements. Explanation: Reacting to a stimulus (seeing the villain draw) is quicker than initiating a movement on your own.

Question 49

After damage to the basal ganglia, a person would most likely experience: A) Uncontrollable, excessive movements in response to stimuli B) Difficulty moving spontaneously but normal reflex responses C) Inability to feel motivated by external rewards D) Total paralysis

Answer 49

Answer: B) Difficulty moving spontaneously but normal reflex responses Explanation: Damage affects self-initiated movements, but stimulus-driven movements can remain relatively intact.

Question 50

Stimulation of dopamine D1 receptors in the direct pathway would likely: A) Slow down movements B) Decrease the motivation to act C) Mimic the effects of receiving a reward D) Impair motor skill learning

Answer 50

Answer: C) Mimic the effects of receiving a reward Explanation: Activation of D1 receptors in the direct pathway enhances behaviors similarly to how a reward would.

Question 51

In Libet's classic experiment on voluntary wrist flexion, what event was found to occur first? A) Conscious decision to move B) Readiness potential in the motor cortex C) Actual wrist movement D) Visual stimulus of the moving light

Answer 51

Answer: B) Readiness potential in the motor cortex Explanation: The readiness potential, an unconscious brain activity, started about 500 ms before movement, while the conscious decision was reported only ~200 ms before the movement.

Question 52

What major conclusion can be drawn from Libet’s wrist-flexing experiment? A) Conscious decision causes movement directly. B) Brain processes begin before conscious awareness of decision. C) People cannot accurately perceive external stimuli timing. D) All voluntary movements are immediate and stimulus-triggered.

Answer 52

Answer: B) Brain processes begin before conscious awareness of decision. Explanation: Brain activity leading to the movement starts before the subject reports consciously deciding to act, suggesting that conscious decisions may just be the awareness of ongoing brain processes.

Question 53

Which of the following best describes a criticism of Libet's findings? A) Motor cortex activity is always instantaneous with conscious decision. B) People are poor at reporting the timing of internal decisions. C) Participants made no spontaneous movements at all. D) The readiness potential does not occur before voluntary movements.

Answer 53

Answer: B) People are poor at reporting the timing of internal decisions. Explanation: Critics argue that individuals might not be very accurate at pinpointing when they made a decision, unlike reacting to external sensory stimuli.

Question 54

In the modified experiment involving letter choices and left/right button pressing, what surprising result was found? A) Decisions were made entirely at random. B) Brain activity predicting choice occurred 7–10 seconds before action. C) Movement was initiated only after external stimuli. D) Motor cortex activity did not predict the choice at all.

Answer 54

Answer: B) Brain activity predicting choice occurred 7–10 seconds before action. Explanation: The researchers could predict participants’ decisions from frontal and parietal cortex activity well before the participants consciously knew which choice they made.

Question 55

Which brain region degenerates in Parkinson’s disease, leading to movement difficulties? A) Globus pallidus B) Substantia nigra C) Striatum D) Thalamus

Answer 55

Answer: B) Substantia nigra Explanation: The gradual loss of dopamine-producing neurons in the substantia nigra causes the major symptoms of Parkinson’s disease

Question 56

Which movement characteristic would most likely be preserved in someone with Parkinson’s disease? A) Initiating spontaneous movement B) Following external signals to move C) Inhibiting inappropriate movements D) Fast voluntary motor actions

Answer 56

Answer: B) Following external signals to move Explanation: Although self-initiated movements are impaired, Parkinson’s patients can often move more normally when reacting to external cues (like a parade).

Question 57

Exposure to which environmental factors has been linked to an increased risk of Parkinson’s disease? A) Ultraviolet radiation and asbestos B) Insecticides, herbicides, and fungicides C) Processed foods and artificial sweeteners D) Airborne pollen and dust mites

Answer 57

Answer: B) Insecticides, herbicides, and fungicides Explanation: Many studies suggest exposure to agricultural chemicals increases Parkinson’s disease risk, especially combined with genetic susceptibility.

Question 58

Which lifestyle factor is associated with a reduced risk of developing Parkinson’s disease? A) High sugar consumption B) Excessive alcohol intake C) Smoking cigarettes D) Lack of exercise

Answer 58

Answer: C) Smoking cigarettes Explanation: Studies have consistently shown that smoking (and coffee drinking) correlates with a lower risk of Parkinson’s disease, although the reasons are still unclear.

Question 59

MPTP, the chemical linked to accidental Parkinson’s-like symptoms in drug users, damages neurons primarily by: A) Increasing acetylcholine production. B) Destroying dopamine-releasing neurons. C) Enhancing mitochondrial function. D) Blocking sodium channels in motor neurons.

Answer 59

Answer: B) Destroying dopamine-releasing neurons. Explanation: MPTP is converted into MPP+, which accumulates in dopamine neurons, damaging mitochondria and leading to cell death

Question 60

What distinction is emphasized between types of movements in the context of voluntary decision-making? A) Reflexes are self-initiated and slow. B) Self-initiated movements are faster than stimulus-triggered ones. C) Self-initiated movements are slower and depend more on basal ganglia. D) Stimulus-triggered movements are largely unconscious and slow.

Answer 60

Answer: C) Self-initiated movements are slower and depend more on basal ganglia. Explanation: Voluntary, spontaneous actions build up slowly, depending on the basal ganglia, unlike quick, stimulus-triggered reactions.

Question 61

Which of the following is NOT a limitation of L-dopa treatment for Parkinson’s disease? A. It causes dopamine release only in deteriorated neurons. B. It produces fluctuations in dopamine levels. C. It does not prevent ongoing neuronal loss. D. It fails to replace other depleted neurotransmitters.

Answer 61

Answer: A Explanation: L-dopa increases dopamine release in all axons, not just deteriorated ones. This widespread release leads to problems.

Question 62

One major reason dopamine itself cannot be administered orally for Parkinson’s disease is because: A. Dopamine breaks down rapidly in the bloodstream. B. Dopamine cannot cross the blood–brain barrier. C. Dopamine triggers a massive immune response. D. Dopamine inhibits basal ganglia activity.

Answer 62

Answer: B Explanation: Dopamine does not cross the blood–brain barrier, which is why its precursor L-dopa is used instead.

Question 63

In addition to L-dopa, Parkinson’s symptoms can be treated with drugs that: A. Enhance serotonin transmission. B. Block dopamine synthesis. C. Directly stimulate dopamine receptors. D. Inhibit neurotrophin release.

Answer 63

Answer: C Explanation: Some drugs directly stimulate dopamine receptors or block dopamine breakdown to ease Parkinson’s symptoms.

Question 64

One hypothesis for why deep brain stimulation helps Parkinson’s patients is that it: A. Enhances neurotrophin production. B. Reduces excessive synchrony in the basal ganglia. C. Increases L-dopa production in the cortex. D. Blocks acetylcholine release in the thalamus.

Answer 64

Answer: B Explanation: Deep brain stimulation may disrupt unhealthy synchronous firing patterns in the basal ganglia.

Question 65

Transplanting fetal neurons into Parkinson’s patients’ brains initially failed largely because: A. The neurons migrated to the spinal cord. B. The immune system attacked the transplanted tissue. C. The fetal cells transformed into glial cells. D. The dopamine produced was immediately degraded.

Answer 65

Answer: B Explanation: Immune rejection was a major problem; later, immunosuppressive drugs improved survival of the grafts.

Question 66

Which of the following best describes the main genetic abnormality causing Huntington’s disease? A. Deletion of a dopamine receptor gene. B. Trinucleotide (C-A-G) repeat expansion in a gene on chromosome 4. C. Mitochondrial DNA mutation causing axonal degeneration. D. Duplication of the serotonin transporter gene.

Answer 66

Answer: B Explanation: Huntington’s is caused by an expanded C-A-G repeat in a gene on chromosome 4.

Question 67

A patient with Huntington’s disease would likely show all of the following symptoms EXCEPT: A. Writhing involuntary movements. B. Memory impairment. C. Excessive inhibition of motor thalamic areas. D. Psychiatric disturbances such as depression

Answer 67

Answer: C Explanation: Basal ganglia damage reduces inhibition of the thalamus, leading to excessive movement, not excessive inhibition.

Question 68

In Huntington’s disease, what relationship exists between the number of CAG repeats and disease onset? A. Fewer repeats = earlier onset B. More repeats = later onset C. More repeats = earlier onset D. The number of repeats does not correlate with onset

Answer 68

Answer: C Explanation: More CAG repeats lead to an earlier onset of Huntington’s symptoms.

Question 69

Which of the following is a correct statement about stem cell therapy for Parkinson’s disease? A. Stem cells cannot differentiate into dopamine-producing cells. B. Stem cells are routinely used in clinical Parkinson’s treatments. C. Stem cell therapy is promising but still faces major challenges. D. Stem cells are ineffective because they overproduce serotonin instead.

Answer 69

Answer: C Explanation: Stem cell strategies sound promising but are not yet perfected for clinical use in Parkinson’s patients.

Question 70

What does the phenomenon where behavioral recovery occurs even when transplanted cells die suggest? A. Neurotrophins released from grafts stimulate brain repair. B. The body’s immune response generates dopamine. C. Non-neuronal cells compensate by producing acetylcholine. D. Surviving neurons lose synaptic plasticity.

Answer 70

Answer: A Explanation: Neurotrophins released by the graft stimulate axon and dendrite growth in the patient's own neurons.