Bio 4

Question 1

Which of the following best describes Mendel’s key contribution to genetics?

A) Inheritance is a blending process of parental traits.
B) Genes are passed down from generation to generation through dominant and recessive inheritance.
C) Inheritance follows the pattern of multiple alleles without any influence from the environment.
D) Inheritance is determined solely by environmental factors.

Answer 1

Answer: B) Genes are passed down from generation to generation through dominant and recessive inheritance.
Explanation: Mendel’s experiments demonstrated that traits are inherited through genes, which exist in pairs and are inherited according to specific laws of dominance and recessiveness. His work refuted the idea of blending inheritance

Question 2

What is the primary distinction between dominant and recessive genes?

A) Dominant genes are only expressed in the homozygous condition.
B) Recessive genes can be expressed even when paired with a dominant gene.
C) Dominant genes show their effect in both homozygous and heterozygous conditions.
D) Recessive genes are more likely to be inherited than dominant genes.

Answer 2

Answer: C) Dominant genes show their effect in both homozygous and heterozygous conditions.
Explanation: Dominant genes exhibit their traits whether the individual is homozygous or heterozygous for that gene, while recessive genes show their effects only in the homozygous condition.

Question 3

If a man and a woman both carry one dominant gene for PTC tasting (T) and one recessive gene for low sensitivity (t), what is the probability that their child will be homozygous for the recessive gene (tt)?

A) 25%
B) 50%
C) 75%
D) 0%

Answer 3

Answer: A) 25%
Explanation: Each parent contributes one allele to the child. The probability of inheriting the recessive allele (t) from both parents is 25%, resulting in a child who is homozygous recessive (tt).

Question 4

Which of the following is an example of a sex-limited gene?

A) Gene for red-green color vision deficiency.
B) Gene for height.
C) Gene for breast size in women.
D) Gene for eye color.

Answer 4

Answer: C) Gene for breast size in women.
Explanation: A sex-limited gene is present in both sexes but is active mainly in one sex. The gene for breast size in women is an example because it is activated by female sex hormones.

Question 5

How do sex-linked genes typically affect males and females differently?

A) Males are more likely to be affected by X-linked recessive traits because they only have one X chromosome.
B) Females are more likely to be affected by X-linked recessive traits because they have two X chromosomes.
C) Both males and females are equally likely to express X-linked recessive traits.
D) Males cannot be affected by X-linked recessive traits.

Answer 5

Answer: A) Males are more likely to be affected by X-linked recessive traits because they only have one X chromosome.
Explanation: Since males have only one X chromosome, if they inherit a recessive gene on their X chromosome, they will express the associated trait. Females, with two X chromosomes, need two copies of the recessive allele to express the trait.

Question 6

Which of the following best describes the genetic code that translates DNA into proteins?

A) The order of bases in RNA determines the amino acid sequence in proteins.
B) The order of bases in DNA directly determines the protein sequence.
C) Only messenger RNA (mRNA) is involved in translating DNA into proteins.
D) Proteins are synthesized directly from DNA without the need for RNA

Answer 6

Answer: A) The order of bases in RNA determines the amino acid sequence in proteins.
Explanation: The process of translation involves mRNA, which is transcribed from DNA. The sequence of bases in the mRNA determines the sequence of amino acids in the resulting protein.

Question 7

Which of the following is a key feature of sex-linked genes on the X chromosome?

A) They are only passed down from father to daughter.
B) They always show dominant inheritance patterns.
C) Males are more likely to be affected by X-linked recessive genes due to the presence of a single X chromosome.
D) X-linked genes only affect female offspring.

Answer 7

Answer: C) Males are more likely to be affected by X-linked recessive genes due to the presence of a single X chromosome.
Explanation: Males, having only one X chromosome, are more vulnerable to X-linked recessive disorders because they lack a second X chromosome to potentially mask the recessive allele.

Question 8

How does the environment influence gene expression according to modern genetics?

A) The environment has no impact on gene expression.
B) The environment can alter the expression of a gene but not its underlying genetic code.
C) Genes can only be expressed if the environmental conditions are exactly controlled.
D) Environmental factors determine the inheritance pattern of a gene

Answer 8

Answer: B) The environment can alter the expression of a gene but not its underlying genetic code.
Explanation: Environmental factors can influence how genes are expressed, but they do not alter the DNA sequence itself. This means gene expression can vary based on external conditions.

Question 9

Which of the following scenarios correctly demonstrates the inheritance of a sex-linked trait?

A) A male inherits a gene for color vision deficiency from his mother and expresses the condition.
B) A female inherits a gene for color vision deficiency from one parent and expresses the condition.
C) A male inherits a dominant gene for color vision from his father and expresses normal vision.
D) A female inherits the gene for color vision deficiency from both parents and expresses normal vision.

Answer 9

Answer: A) A male inherits a gene for color vision deficiency from his mother and expresses the condition.
Explanation: Males inherit their X chromosome from their mother and their Y chromosome from their father. If they inherit a recessive X-linked gene for color vision deficiency, they will express the condition because they only have one X chromosome.

Question 10

Which of the following statements best explains why most point mutations are not beneficial in evolutionary terms?

A. Mutations always disrupt protein synthesis entirely.
B. Evolution has already optimized gene sequences, making most mutations detrimental.
C. Mutations only occur in non-coding DNA.
D. Mutations are typically reversed by natural cellular repair mechanisms.

Answer 10

Answer: B
Explanation: Evolution has had extensive time to select advantageous gene variants, so most mutations disrupt finely-tuned genetic functions. However, rare beneficial mutations—such as those seen in the FOXP2 gene—can have significant evolutionary impact.

Question 11

Which type of mutation is most likely to result in schizophrenia or neurological disorders, according to current research?

A. Silent point mutations
B. Frameshift mutations caused by insertion
C. Microduplications and microdeletions
D. Substitutions in mitochondrial DNA

Answer 11

Answer: C
Explanation: Microduplications and microdeletions—changes affecting small chromosome segments—have been linked to several brain-related conditions, including some forms of schizophrenia.

Question 12

Epigenetic modifications can be passed to the next generation. Which of the following findings best supports this claim?

A. Histone modifications are always reset during fertilization.
B. Rats conditioned to fear a sound have offspring that also fear it.
C. Mice exposed to specific odors produced offspring with increased sensitivity to that odor.
D. Red blood cells show unique patterns of gene expression.

Answer 12

Answer: C
Explanation: The study with mice conditioned to fear an odor, where their offspring also displayed heightened sensitivity, supports the concept of transgenerational epigenetic inheritance.

Question 13

How does the addition of acetyl groups to histones influence gene expression?

A. It tightens DNA winding, silencing the gene.
B. It loosens DNA from histones, enhancing gene expression.
C. It causes RNA to degrade prematurely.
D. It recruits methyl groups to promote transcription.

Answer 13

Answer: B
Explanation: Acetylation of histone tails relaxes the grip of histones on DNA, allowing genes to become more accessible for transcription, thus increasing their expression.

Question 14

Which scenario exemplifies an epigenetic change rather than a genetic mutation?

A. A base pair substitution in the FOXP2 gene.
B. A duplication of a chromosome segment during meiosis.
C. Increased gene expression due to social isolation.
D. A deletion of a tumor suppressor gene.

Answer 14

Answer: C
Explanation: Epigenetics refers to changes in gene expression without altering the DNA sequence. Social isolation alters the expression of hundreds of genes, fitting the epigenetic definition.

Question 15

What does “heritability” measure?
A) The influence of prenatal nutrition on behavior
B) The extent to which genes contribute to individual differences in a trait
C) The impact of environment on personality
D) The ability to pass a trait to the next generation

Answer 15

Answer: B
Explanation: Heritability refers to how much of the variation in a trait across individuals in a population is due to genetic differences—not about whether a trait is inherited at all.

Question 16

What are “virtual twins”?
A) Twins born via IVF
B) Identical twins raised in different environments
C) Unrelated children of the same age raised together from infancy
D) Cloned siblings with shared DNA

Answer 16

Answer: C
Explanation: Virtual twins are genetically unrelated but grow up in the same environment—similarities point to environmental effects, while differences can highlight genetic ones.

Question 17

Which trait has not shown significant heritability in studies?
A) Neuroticism
B) Childhood misbehavior
C) Religious affiliation
D) Cognitive performance

Answer 17

Answer: C
Explanation: While most behaviors show some heritability, religious affiliation is heavily shaped by environment, family, and culture rather than genetics.

Question 18

Why can heritability estimates differ between populations?
A) Genes evolve rapidly in different regions
B) Environmental differences can mask or amplify genetic influences
C) People in one region may lie on surveys
D) Twin studies are unreliable outside the U.S.

Answer 18

Answer: B
Explanation: If environments vary widely, genetics may play a smaller role; if environments are more uniform, genetic effects become more visible.

Question 19

What is one major limitation of genome-wide association studies (GWAS)?
A) They only study twins
B) They ignore environmental factors
C) They test thousands of genes, increasing the risk of false positives
D) They are outdated and rarely used

Answer 19

Answer: C
Explanation: Because GWAS tests many genes simultaneously, there’s a higher chance of finding misleading links by coincidence—especially in small or diverse samples.

Question 20

What does the condition PKU illustrate about heritability?
A) Genetic conditions are always untreatable
B) A heritable trait can still be modified by environment
C) Environmental changes have no impact on genetic disorders
D) It only affects people of Asian descent

Answer 20

Answer: B
Explanation: PKU is a genetic disorder, but it can be managed through diet, showing that even high-heritability traits can be altered by environmental interventions.

Question 21

Which dietary substance must people with PKU strictly avoid?
A) Gluten
B) Lactose
C) Phenylalanine
D) Caffeine

Answer 21

Answer: C
Explanation: PKU prevents proper metabolism of phenylalanine, which builds up to toxic levels and harms brain development unless it’s restricted from the diet.

Question 22

According to behavioral genetics, what is true of most psychological traits?
A) They are entirely shaped by the environment
B) They are caused by a single gene
C) They are influenced by many genes, each with small effects
D) They show no genetic influence

Answer 22

Answer: C
Explanation: Most traits in psychology show moderate heritability, typically due to the combined effect of many genes rather than any one major gene.

Question 23

Which of the following best illustrates how a gene can influence behavior indirectly?

A. A gene directly stimulates aggression through amygdala activation.
B. A gene influences a person’s height, which leads to basketball success and time spent practicing.
C. A gene changes dopamine production, altering mood.
D. A gene expresses only in neurons, changing reaction times.

Answer 23

Correct Answer: B
Explanation: The gene influences height, which leads to a behavior (playing basketball) due to environmental reinforcement. This is an example of indirect influence through changing the environment.

Question 24

Why does the idea of Lamarckian evolution not align with modern biology?

A. It supports natural selection, which contradicts genetic inheritance.
B. It requires that acquired traits change gene sequences, which they do not.
C. It ignores the role of mutation in evolution.
D. It assumes traits are lost over time due to environmental pressures.

Answer 24

Correct Answer: B
Explanation: Lamarckian evolution wrongly suggests that traits acquired in one’s lifetime (e.g., muscle growth) can be passed to offspring. Modern biology shows acquired traits do not alter genes.

Question 25

What determines whether a gene is considered evolutionarily “fit”? A. The intelligence it provides B. Its ability to improve an individual’s health C. How many copies of it persist into future generations D. The size of the population it exists in

Answer 25

Correct Answer: C Explanation: Fitness is defined operationally as the number of gene copies that survive and reproduce. It’s about reproductive success, not personal traits.

Question 26

Why does natural selection not typically favor traits that benefit the species but harm the individual? A. Because group-level selection is stronger than gene-level selection B. Because such traits increase the individual's reproductive success C. Because individuals with those traits leave fewer offspring D. Because evolution occurs at the community level

Answer 26

Correct Answer: C Explanation: Evolution works at the level of genes and individuals. A trait that helps the group but reduces individual reproduction will likely be eliminated over time.

Question 27

Which scenario challenges the misconception that humans have stopped evolving? A. Most people survive into old age B. All genes are now equally represented C. People with certain traits have more offspring D. Disease no longer affects reproduction

Answer 27

Correct Answer: C Explanation: Evolution depends on differential reproduction, not survival. If people with certain genes have more children, evolution is still occurring

Question 28

Which of the following best illustrates the principle of kin selection? A) A chimpanzee shares food with a familiar nonrelative. B) A meerkat emits an alarm call that warns the colony. C) A human donates a kidney to a stranger. D) A squirrel risks its life to save its siblings from a predator.

Answer 28

Answer: D Explanation: Kin selection favors behaviors that help genetic relatives. Risking one's life for siblings supports the spread of shared genes.

Question 29

According to evolutionary psychology, why do humans still experience goose bumps? A) They help regulate body temperature in modern environments. B) They are a learned response to fear or cold. C) They are vestigial traits inherited from ancestors where the function was adaptive. D) They are primarily cultural behaviors influenced by tradition.

Answer 29

Answer: C Explanation: Goose bumps are a vestigial response, useful in ancestors with thick body hair (e.g., for insulation or appearing larger when threatened).

Question 30

Which of the following behaviors is most consistent with reciprocal altruism? A) A lioness protects her cubs from a predator. B) A human gives money to a panhandler and expects nothing in return. C) A person helps a neighbor fix their car, expecting help in the future. D) A bird calls out to alert the flock while eating.

Answer 30

Answer: C Explanation: Reciprocal altruism involves helping others with the expectation of future help—"I help you, you help me later."

Question 31

What is the biggest evolutionary limitation of altruistic behavior toward nonrelatives? A) It violates natural selection. B) It is always punished by others in the group. C) It benefits the group, not the individual’s reproductive success. D) It usually involves physical harm to the altruist.

Answer 31

Answer: C Explanation: A behavior must increase individual reproductive success to be favored by natural selection; benefiting the group alone is not sufficient.

Question 32

Why might humans have evolved to age and die after their reproductive years, according to evolutionary psychology? A) It reduces population pressure on resources. B) It ensures cultural wisdom is passed on. C) It prevents competition with offspring for resources. D) It allows time for spiritual growth and development.

Answer 32

Answer: C Explanation: One theory suggests that post-reproductive death reduces competition with younger generations, possibly enhancing the survival of one’s own genes.

Question 33

Why do bears and birds differ in their eating behaviors, from an evolutionary perspective? A) Bears are larger, so they require more food. B) Birds have more social interactions. C) Each species evolved behaviors that best suit their survival and reproductive needs. D) Birds are more intelligent, so they self-regulate food intake better.

Answer 33

Answer: C Explanation: This reflects the functional explanation: each species evolves behaviors that support its ecological needs and survival strategy.

Question 34

Which of the following statements best reflects a criticism of evolutionary psychology? A) It focuses too heavily on genetic inheritance. B) It ignores the role of the brain in behavior. C) It relies on functional explanations that are rarely tested. D) It only studies nonhuman animal behavior.

Answer 34

Answer: C Explanation: A major criticism is that some evolutionary explanations are speculative and not empirically tested

Question 35

In what way is group selection considered viable in humans but less so in other species? A) Humans have larger brains. B) Humans can fly from group to group. C) Humans can punish or exclude cheaters. D) Humans do not need kin to cooperate.

Answer 35

Answer: C Explanation: Group selection is more plausible in humans because we can enforce cooperation by punishing or excluding non-cooperative individuals

Question 36

What is the function of homeobox genes in early development? A) Produce neurotransmitters B) Control hormone release C) Regulate anatomical development D) Aid in muscle contractions

Answer 36

Answer: C) Regulate anatomical development Explanation: Homeobox genes regulate the expression of other genes and control anatomical development, such as body orientation.

Question 37

What structure forms from the dorsal surface during early development of the central nervous system? A) Neural tube B) Prefrontal cortex C) Spinal column D) Medulla oblongata

Answer 37

Answer: A) Neural tube Explanation: The dorsal surface thickens and forms a neural tube, which later becomes the spinal cord and brain structures.

Question 38

At what age do muscle movements begin in human embryos? A) 5 weeks B) 7.5 weeks C) 10 weeks D) Birth

Answer 38

Answer: B) 7.5 weeks Explanation: Muscle movements begin spontaneously at 7.5 weeks and help stretch the muscles, even before sensory systems are active.

Question 39

Which area of the brain shows the most development during early infancy? A) Primary sensory cortex B) Spinal cord C) Prefrontal cortex D) Cerebellum

Answer 39

Answer: C) Prefrontal cortex Explanation: While sensory areas are more mature at birth, the prefrontal cortex undergoes the most change in the first few years.

Question 40

What process involves the production of new neurons? A) Migration B) Differentiation C) Synaptogenesis D) Proliferation

Answer 40

Answer: D) Proliferation Explanation: Proliferation is the stage where new cells (neurons and glia) are produced, especially during early brain development.

Question 41

What guides the migration of neurons during brain development? A) DNA methylation B) Hormones C) Immunoglobulins and chemokines D) Neurotransmitters

Answer 41

Answer: C) Immunoglobulins and chemokines Explanation: These chemicals guide neuron migration; deficits can cause brain size reduction and intellectual disabilities.

Question 42

What is the name of the process by which synapses are formed? A) Myelination B) Differentiation C) Synaptogenesis D) Neurogenesis

Answer 42

Answer: C) Synaptogenesis Explanation: Synaptogenesis refers to the creation of synaptic connections between neurons, which continues throughout life.

Question 43

Which part of the brain is responsible for continuous neurogenesis in adulthood? A) Cerebellum B) Hippocampus C) Cortex D) Thalamus

Answer 43

Answer: B) Hippocampus Explanation: The hippocampus continues to generate new neurons in adults and plays a key role in memory formation.

Question 44

What method helped researchers determine neuron formation dates in the human brain? A) fMRI B) Genetic sequencing C) Carbon-14 dating D) CT scans

Answer 44

Answer: C) Carbon-14 dating Explanation: Researchers used atmospheric C-14 levels (affected by nuclear testing) to date when neurons were formed.

Question 45

Which brain region forms few or no new neurons after birth in humans? A) Olfactory bulb B) Hippocampus C) Cerebral cortex D) Striatum

Answer 45

Answer: C) Cerebral cortex Explanation: C-14 studies showed that neurons in the cerebral cortex are as old as the person, indicating minimal postnatal neurogenesis.

Question 46

What did Paul Weiss conclude from his salamander limb graft experiment? A. Axons precisely find their original targets B. Muscles guide axons using chemical signals C. Axons attach randomly and muscles respond selectively D. Axons fail to regenerate in amphibians

Answer 46

Answer: C. Axons attach randomly and muscles respond selectively Explanation: Weiss believed axons sent random signals, and muscles responded only to the appropriate one—like radios tuned to a specific station.

Question 47

Why was the salamander a useful species for Weiss’s and Sperry’s experiments? A. It has a simple nervous system B. Its optic nerves never regenerate C. It can regenerate axons and accept limb grafts D. It responds faster to chemical cues than mammals

Answer 47

Answer: C. It can regenerate axons and accept limb grafts Explanation: Salamanders accept transplants like extra limbs and their axons can regrow after damage—ideal for studying pathfinding.

Question 48

What did Roger Sperry’s rotated-eye experiment demonstrate? A. Eyes can adapt to new visual orientations B. Axons grow randomly and still restore vision C. Axons follow chemical cues to reconnect with original targets D. Tectum can reprogram axon destinations

Answer 48

Answer: C. Axons follow chemical cues to reconnect with original targets Explanation: Even after eye rotation, axons grew back to their original tectum locations, showing they follow a chemical trail.

Question 49

What visual effect did Sperry observe in newts after rotating their eyes 180 degrees? A. Vision was unaffected B. The newts saw everything in black and white C. The newts saw the world upside down and reversed D. Vision was completely lost in one eye

Answer 49

Answer: C. The newts saw the world upside down and reversed Explanation: Because axons reconnected to their original targets despite the rotated eye, visual perception was inverted.

Question 50

How do axons find their target areas, according to modern research? A. By trial and error B. By direct electrical stimulation C. By following gradients of chemical signals D. By replicating neighboring neurons' paths

Answer 50

Answer: C. By following gradients of chemical signals Explanation: Axons are guided by attractive and repellent chemical cues and align with target cells that have matching chemical concentrations

Question 51

What role do chemical gradients play in axon pathfinding? A. They block incorrect connections B. They allow only dorsal axons to grow C. They help axons sort themselves onto target regions D. They stimulate neurons to grow faster

Answer 51

Answer: C. They help axons sort themselves onto target regions Explanation: Axons align with areas on the target (like the tectum) based on similar levels of certain proteins, guiding precise connections.

Question 52

What happens when axons first reach their target area? A. They immediately form perfect connections B. They form synapses with many nearby cells C. They wait for light exposure before connecting D. They only form one synapse per axon

Answer 52

Answer: B. They form synapses with many nearby cells Explanation: Axons initially connect with multiple nearby cells, and over time, the system strengthens the best connections and eliminates the rest

Question 53

What mechanism allows postsynaptic cells to refine their synaptic inputs during development? A. Exposure to light B. Electrical stimulation C. Patterned spontaneous activity D. Gene mutation

Answer 53

Answer: C. Patterned spontaneous activity Explanation: Before birth, spontaneous waves of activity in the retina help the thalamus identify and strengthen synapses from adjacent retinal cells

Question 54

What principle does the developmental selection of synapses resemble? A. Synaptic thermodynamics B. Neuroplasticity C. Neural Darwinism D. Synaptic compensation

Answer 54

Answer: C. Neural Darwinism Explanation: This principle suggests that synapses compete for survival, similar to natural selection—only the most effective connections persist.

Question 55

What discovery is Rita Levi-Montalcini known for? A. Synaptic pruning B. Brain plasticity C. Neurotransmitter recycling D. Nerve growth factor (NGF)

Answer 55

Answer: D. Nerve growth factor (NGF) Explanation: Levi-Montalcini discovered NGF, a chemical released by muscles that promotes the survival of sympathetic neurons.

Question 56

What determines whether a neuron in the sympathetic nervous system survives? A. Random selection B. The size of the muscle C. Receiving NGF from a target D. Direct stimulation by the spinal cord

Answer 56

Answer: C. Receiving NGF from a target Explanation: Only neurons that make successful synapses and receive NGF survive—others undergo apoptosis.

Question 57

What is apoptosis? A. A kind of scar tissue B. Random death of brain cells due to toxins C. Programmed cell death based on failure to connect D. A disease process in degenerative conditions

Answer 57

Answer: C. Programmed cell death based on failure to connect Explanation: Apoptosis is a built-in "self-destruct" mechanism for neurons that fail to form useful connections.

Question 58

What is the main role of neurotrophins like NGF and BDNF? A. Triggering neurotransmitter release B. Enhancing myelin production C. Promoting neuron survival and synaptic growth D. Reducing inflammation in the brain

Answer 58

Answer: C. Promoting neuron survival and synaptic growth Explanation: Neurotrophins nourish neurons, aiding in growth, synapse formation, and learning.

Question 59

Which of the following statements about cortical neurons is TRUE? A. Neurotrophins prevent their death B. Light exposure ensures their survival C. They die based on lack of incoming input D. They never undergo apoptosis

Answer 59

Answer: C. They die based on lack of incoming input Explanation: Unlike peripheral neurons, cortical neuron survival depends heavily on receiving adequate input from other neurons.

Question 60

According to Lewis Wolpert, which stage of life is the most important? A. Birth B. Marriage C. Gastrulation D. Death

Answer 60

Correct Answer: C. Gastrulation Explanation: Wolpert emphasized gastrulation as the most important time because it is a critical stage in embryonic development; errors here can be fatal.

Question 61

Why is the developing brain more vulnerable to malnutrition, chemicals, and infections? A. Because it lacks a blood-brain barrier B. Because it is not yet connected to the nervous system C. Because critical developmental processes are actively occurring D. Because the immune system is stronger in infants

Answer 61

Correct Answer: C. Because critical developmental processes are actively occurring Explanation: Disruptions during development can have long-lasting or fatal consequences since neurons are forming, migrating, and connecting.

Question 62

What is a long-term consequence of thyroid deficiency in infants? A. Obesity B. Hyperactivity C. Mental retardation D. Hearing loss

Answer 62

Correct Answer: C. Mental retardation Explanation: In infants, thyroid deficiency due to iodine shortage can severely impact brain development, leading to intellectual disabilities.

Question 63

Alcohol affects the developing brain by: A. Enhancing glutamate activity B. Increasing neuron proliferation C. Inhibiting glutamate and enhancing GABA receptors D. Preventing myelination of axons

Answer 63

Correct Answer: C. Inhibiting glutamate and enhancing GABA receptors Explanation: Alcohol reduces excitatory input by affecting glutamate and GABA, leading to neuron death via apoptosis.

Question 64

What happens when alcohol leaves the system after compensatory upregulation of glutamate receptors? A. Neurons become less responsive B. Excess excitation poisons neurons C. GABA receptors dominate D. Neurons revert to normal activity

Answer 64

Correct Answer: B. Excess excitation poisons neurons Explanation: Glutamate overstimulates its receptors, causing sodium and calcium influx and mitochondrial damage, leading to neuron death.

Question 65

Maternal stress can lead to: A. Improved immune response in offspring B. Increased grooming in rats C. Long-term fear responses in offspring D. Reduced cortisol levels in offspring

Answer 65

Correct Answer: C. Long-term fear responses in offspring Explanation: Stress alters maternal behavior, such as less grooming, which in turn increases anxiety and fearfulness in offspring.

Question 66

When immature neurons are transplanted early in development, they: A. Die quickly in the new location B. Retain all old characteristics C. Develop features of the new location D. Stop differentiating

Answer 66

Correct Answer: C. Develop features of the new location Explanation: Early-stage neurons are plastic and adapt to their new environment’s functional properties.

Question 67

In the ferret experiment, the auditory thalamus receiving visual input led to: A. Auditory responses to visual stimuli B. Blindness in the ferrets C. Visual responses in the auditory cortex D. No functional change

Answer 67

Correct Answer: C. Visual responses in the auditory cortex Explanation: The auditory cortex adapted and processed visual information, showing the brain’s early plasticity.

Question 68

What do the ferret and mouse experiments collectively show about sensory input? A. Sensory input has no effect on cortical development B. Sensory input determines cortical identity to some extent C. All sensory input is pre-programmed D. Only visual input influences the cortex

Answer 68

Correct Answer: B. Sensory input determines cortical identity to some extent Explanation: These studies demonstrate that input from the senses can shape how brain areas develop and function.

Question 69

Which of the following best supports the idea that experience remodels the adult brain? A. Dendritic structures stabilize completely after adolescence. B. Brain scans of sighted and blind individuals show identical occipital activity. C. Dendritic spines undergo turnover, reflecting synaptic plasticity. D. Adult neurons cannot form new connections.

Answer 69

Answer: C Explanation: Turnover of dendritic spines indicates synapse formation and elimination, showing that even in adults, the brain is dynamically remodeled by experience.

Question 70

Why do blind individuals show occipital cortex activity during tactile tasks like Braille reading? A. Their visual cortex undergoes degeneration. B. The occipital cortex is recruited for processing touch stimuli. C. Their somatosensory cortex migrates into the occipital lobe. D. The visual cortex only activates during imagined visual input.

Answer 70

Answer: B Explanation: In the absence of visual input, blind individuals repurpose the occipital cortex to process tactile information, such as Braille—demonstrating cortical plasticity.

Question 71

Which statement about enriched environments and physical activity is most accurate? A. Only social interaction, not exercise, promotes neuronal growth. B. Wild rats have fewer neurons than lab rats due to unpredictability. C. Physical activity alone can stimulate dendritic and axonal growth. D. Dendritic branching is unaffected by environmental enrichment.

Answer 71

Answer: C Explanation: Physical activity, such as running, independently enhances neuronal growth and learning, even in the absence of social interaction or cognitive challenges.

Question 72

What does the term "far transfer" refer to in the context of cognitive training? A. Improvement in the same skill that was trained. B. Using one sensory modality to replace another. C. Enhancement in a different, unrelated intellectual domain. D. Transfer of skills across physical locations.

Answer 72

Answer: C Explanation: "Far transfer" is the idea that learning one difficult task (like Latin or Sudoku) will enhance performance in unrelated intellectual areas—an effect research finds to be weak.

Question 73

Which of the following findings supports the idea of sensory substitution in the brain? A. Enhanced auditory responses in the visual cortex of blind individuals. B. Stronger motor cortex activation in professional athletes. C. Improved sleep regulation from enriched environments. D. Occipital inactivation impairs touch in sighted individuals

Answer 73

Answer: A Explanation: Sensory substitution occurs when one sensory area (e.g., the occipital/visual cortex) processes non-visual stimuli, as seen in blind individuals using sound or touch.

Question 74

What evidence best supports the view that musical training alters brain structure? A. Increased pain threshold in musicians. B. Larger temporal cortical areas and stronger auditory responses. C. Higher IQ scores in trained musicians across all domains. D. Stronger prefrontal inhibition during silence.

Answer 74

Answer: B Explanation: Musicians show enhanced neural activity in auditory areas and structural differences in the temporal cortex, directly linking training to brain changes.

Question 75

In comparing the effects of different environments on rats, what was a critical confounding factor researchers needed to address? A. Nutritional intake across groups. B. Genetics of the wild-caught rats. C. Lighting differences in the cages. D. Volume of water consumed dailyx

Answer 75

Answer: B Explanation: Comparing lab-reared and wild rats introduces potential genetic differences, which could confound conclusions about the effects of environmental enrichment.

Question 76

Which of the following best supports the claim that brief experiences can alter brain anatomy? A. Brain scans of musicians show enlarged motor cortices. B. Adults who learned to juggle showed enlargement in specific brain areas, which were even more expanded in expert jugglers. C. Adolescents display immature prefrontal cortex activity. D. Motor cortex changes lead to finger overlap in musicians with dystonia.

Answer 76

Correct Answer: B Explanation: The finding that novice jugglers had measurable brain changes that were also seen, but more strongly, in expert jugglers supports the idea that short-term learning experiences can induce observable brain anatomy changes.

Question 77

Which methodological issue raises skepticism about studies on short-term brain plasticity? A. Lack of a control group B. Use of subjective measures C. Testing a large number of brain areas at once increases risk of false positives D. Only using adolescent participants

Answer 77

Correct Answer: C Explanation: Critics argue that comparing many brain areas simultaneously without proper statistical correction increases the likelihood of finding a result by chance, a problem known as the multiple comparisons problem.

Question 78

What is the primary cause of "musician’s cramp" (focal hand dystonia)? A. Joint overuse and arthritis B. Peripheral nerve damage from repetitive motion C. Brain reorganization leading to overlapping cortical representations D. Tendon inflammation from poor technique

Answer 78

Correct Answer: C Explanation: Focal hand dystonia results from maladaptive plasticity in the somatosensory and motor cortex, where finger representations begin to overlap and interfere with each other.

Question 79

Which treatment approach is currently favored for musician’s cramp based on the understanding of its neural basis? A. Surgery on affected tendons B. Cortical inhibition via pharmaceuticals C. Proprioceptive retraining and targeted rehabilitation D. Anti-inflammatory medication

Answer 79

Correct Answer: C Explanation: Because the issue lies in brain reorganization, proprioceptive training—which retrains muscle sensation and control—is more effective than purely physical or pharmacological intervention

Question 80

Why is immaturity of the prefrontal cortex considered only a partial explanation for adolescent impulsivity? A. Adolescents’ brains are structurally identical to adults’ B. Most impulsive adolescents have no behavioral issues as children C. Adolescents often perform similarly to adults on impulse-control tasks D. Risky behavior decreases during late teenage years

Answer 80

Correct Answer: C Explanation: Despite anatomical immaturity, most adolescents perform comparably to adults on lab tasks measuring impulse inhibition. This implies other factors contribute more significantly to real-world risk-taking.

Question 81

What neurological change most likely contributes to increased risk-taking behavior in late adolescence? A. Decrease in amygdala activity B. Increased anticipatory reward responses in the brain C. Decrease in dopamine production D. Decreased connectivity between motor and sensory cortices

Answer 81

Correct Answer: B Explanation: Risk-taking peaks during adolescence largely because of heightened reward anticipation, particularly in social or peer-influenced contexts.

Question 82

Which of the following accurately distinguishes the effects of ischemic vs. hemorrhagic strokes? A. Ischemia causes neurons to flood with oxygen, hemorrhage deprives them of oxygen. B. Both types lead to the same damage because they affect sodium–potassium pump function. C. Hemorrhages are more treatable than ischemia due to increased blood supply. D. Only ischemia results in neuron overstimulation from glutamate release.

Answer 82

Answer: B Explanation: Despite different causes, both ischemic and hemorrhagic strokes lead to similar harmful outcomes like edema, pump failure, and glutamate-induced overstimulation.

Question 83

Which of the following best explains the limited effectiveness of many stroke treatments in humans despite promising animal research? A. Animal brains do not use glutamate as a neurotransmitter. B. Humans receive treatments too soon after stroke onset. C. Human stroke patients are often older and treated later than lab animals. D. Ethical concerns limit treatment options in animals, not humans.

Answer 83

Answer: C Explanation: Human patients differ from healthy lab animals in age and health and often receive treatments later, reducing treatment effectiveness.

Question 84

What is the rationale behind considering cannabinoids as a treatment for stroke? A. They rapidly increase glucose to oxygen-starved neurons. B. They eliminate sodium buildup in neurons. C. They reduce glutamate release and have anti-inflammatory effects. D. They accelerate recovery of damaged synapses.

Answer 84

Answer: C Explanation: Cannabinoids may protect against stroke damage by reducing glutamate toxicity and inflammation—two major contributors to post-stroke neuronal death.

Question 85

Why might transfusing blood from young mice into older mice improve learning and memory? A. Young blood has more glucose to fuel brain activity. B. Young blood promotes synapse pruning for efficiency. C. Young blood increases dendritic spine formation in the older brain. D. Young blood contains more neurotransmitters.

Answer 85

Answer: C Explanation: Studies showed that young blood enhances dendritic spine density in older mice, potentially supporting better memory and learning functions.

Question 86

Which of the following best explains the concept of diaschisis? A) The growth of axons from the opposite hemisphere into damaged brain regions B) The formation of scar tissue by astrocytes around damaged neurons C) The decreased activity in surviving brain areas due to loss of input from damaged areas D) The increased sensitivity of receptors following neuron denervation

Answer 86

Answer: C Explanation: Diaschisis refers to reduced activity in neurons that survive but are functionally impacted by loss of input from nearby damaged neurons.

Question 87

Which of the following is true regarding scar tissue formed by astrocytes after CNS injury? A) It inhibits neuronal survival and should be removed to facilitate recovery B) It primarily serves to block axon regrowth and must be suppressed C) It promotes axonal growth by guiding regenerating fibers D) It helps protect nearby neurons and its removal can lead to degeneration

Answer 87

Answer: D Explanation: Although scar tissue was once thought to block recovery, more recent findings show astrocytes in scar tissue release protective chemicals; removing the scar worsens tissue damage.

Question 88

Collateral sprouting is most likely to impair recovery when: A) It occurs too early in the recovery process B) It occurs in sensory pathways rather than motor pathways C) New axons convey information inconsistent with the lost input D) Sprouting takes place in the peripheral nervous system rather than the CNS

Answer 88

Answer: C Explanation: Collateral sprouting can be detrimental when the new axons transmit different information than the lost ones, disrupting functional recovery.

Question 89

Which mechanism is least likely to contribute to recovery of function following brain damage? A) Axon sprouting from nearby neurons B) Dopamine receptor supersensitivity C) Formation of scar tissue by astrocytes D) Immediate regeneration of CNS axons

Answer 89

Answer: D Explanation: Unlike the PNS, axons in the mammalian CNS rarely regenerate effectively after injury, making this mechanism the least likely to aid in recovery.

Question 90

The behavioral recovery seen in rats treated with amphetamine after cortical damage is most likely due to: A) Enhanced axonal regrowth B) Increased dopamine activity promoting stimulation of underactive neurons C) Inhibition of scar tissue formation D) Reduced receptor sensitivity to neurotransmitters

Answer 90

Answer: B Explanation: Amphetamines increase dopamine levels, which enhances stimulation in underactive neurons and helps overcome diaschisis-related deficits.

Question 91

The most critical factor in the effectiveness of axon regrowth therapies in lab animals is: A) Removal of myelin debris B) Elimination of astrocytes near the damage site C) Consistent behavioral practice and stimulation after regrowth D) Blocking glial scar formation using neurotrophins

Answer 91

Answer: C Explanation: Even when axon regrowth occurs, behavioral recovery requires repeated practice to help re-establish functional circuits.

Question 92

Denervation supersensitivity is thought to contribute to: A) Suppression of collateral sprouting B) Increased sensitivity of neurons to neurotransmitters following loss of input C) Complete regeneration of damaged axons in the CNS D) The inhibition of neurotrophin secretion by inactive neurons

Answer 92

Answer: B Explanation: Denervation supersensitivity refers to neurons becoming more sensitive due to loss of input, often observed in dopaminergic systems.

Question 93

Which of the following statements is most accurate about dopaminergic drugs in the context of neural recovery? A) They directly induce axon regeneration in the mammalian CNS B) Their use is safe and effective for enhancing recovery in human patients C) They can enhance behavioral performance by increasing neural stimulation D) They are primarily effective by reducing astrocyte scar formation

Answer 93

Answer: C Explanation: Dopaminergic drugs like amphetamine enhance behavioral recovery by stimulating neural activity, especially where diaschisis has occurred.

Question 94

Which of the following best explains why a person might feel a phantom limb sensation on the hand when the face is touched? A. The nerve endings in the stump are hyperactive. B. The face and hand share the same spinal nerve roots. C. Axons representing the face sprouted into cortical areas formerly devoted to the hand. D. Visual feedback from mirrors creates the illusion of hand stimulation.

Answer 94

Correct Answer: C Explanation: After amputation, the cortical area that originally responded to the hand is taken over by inputs from adjacent areas like the face. Touching the face can then activate this reassigned cortical territory, leading to a phantom hand sensation.

Question 95

What does the case of a monkey regaining limb usage after deafferentation of both forelimbs illustrate about brain plasticity and behavior? A. Permanent motor damage follows sensory loss. B. Recovery is impossible without sensory input. C. The animal retains the ability but avoids using the impaired limb when alternatives exist. D. Only younger animals can recover function after nerve damage.

Answer 95

Correct Answer: C Explanation: The monkey’s behavior suggests that lack of limb use is due to behavioral choice, not incapacity. When both limbs are impaired, the monkey uses both, indicating retained motor ability despite sensory loss.

Question 96

Denervation supersensitivity is best described as: A. A strengthening of the skeletal muscles in response to repeated trauma. B. A brain region becoming less sensitive after losing input. C. An increased sensitivity of postsynaptic neurons after losing some of their normal inputs. D. New axons growing and forming connections in random brain regions.

Answer 96

Correct Answer: C Explanation: Denervation supersensitivity occurs when neurons that lose some input become more responsive to any remaining or new inputs, increasing sensitivity to stimulation.

Question 97

In the case of long-term cortical reorganization, why does touch on the face evoke sensations perceived as coming from the amputated hand? A. The somatosensory cortex randomly rewires itself. B. Cortical cells have entirely lost their identity. C. The original cortical representation of the hand persists and interprets input as if from the hand. D. The face and hand share the same motor representation.

Answer 97

Correct Answer: C Explanation: Even after sensory input is lost, the "identity" of the cortical area remains. So, when it starts receiving inputs from elsewhere (like the face), the brain still interprets the stimulation as coming from the original source—in this case, the hand.

Question 98

What is a likely mechanism for the reduction or elimination of phantom limb pain when using a prosthetic limb? A. The prosthetic reestablishes original nerve connections. B. The prosthetic limb blocks nerve impulses in the stump. C. Sensory input from the prosthetic is integrated into the somatosensory cortex, displacing abnormal connections. D. The visual appearance of a limb suppresses pain circuits.

Answer 98

Correct Answer: C Explanation: The brain begins to attribute sensation to the prosthetic, helping displace the reorganized but abnormal neural inputs that created the phantom limb pain.

Question 99

What does the example of a man feeling orgasm in a phantom foot during sexual arousal suggest about cortical organization? A. Sensory areas can generate false memories. B. Sexual stimulation can reactivate childhood reflexes. C. Genital representation can invade adjacent foot areas in the cortex. D. The spinal cord governs sexual sensations more than the brain.

Answer 99

Correct Answer: C Explanation: The somatosensory cortex map places feet and genitals next to each other. After amputation, the cortical area for the foot can be taken over by genital input, leading to sensations like orgasm being “felt” in the phantom foot.