Chapter 4 Flashcards by Ms Lucy

An action that benefits someone other than the actor

altruistic behavior

How well did you know this?

Not at all

Perfectly

A process of selecting plants/animals for desired traits

Artificial selection

How well did you know this?

Not at all

Perfectly

all chromosomes other than X and Y

autosomal genes

How well did you know this?

Not at all

Perfectly

strands of genes

chromosomes

How well did you know this?

Not at all

Perfectly

double-stranded molecule that is part of the chromosomes

deoxyribonucleic acid (DNA)

How well did you know this?

Not at all

Perfectly

fraternal (non-identical) twins derived from two eggs

dizygotic

How well did you know this?

Not at all

Perfectly

gene that shows a strong effect in either the homozygous or heterozygous condition

dominant

How well did you know this?

Not at all

Perfectly

a field that deals with changes in gene expression without modification of the DNA sequence

epigenetics

How well did you know this?

Not at all

Perfectly

field that deals with how behaviors evolved

evolutionary psychology

How well did you know this?

Not at all

Perfectly

the spreading of genes; number of copies of one’s genes that endure in later generations

fitness

How well did you know this?

Not at all

Perfectly

units of heredity that maintain their structural identity from one generation to another

genes

How well did you know this?

Not at all

Perfectly

estimate of the degree to which variation in a characteristic depends on genetic variations in a given population

heritability

How well did you know this?

Not at all

Perfectly

having two unlike genes for a given trait

heterozygous

How well did you know this?

Not at all

Perfectly

having two identical genes for a given characteristic

homozygous

How well did you know this?

Not at all

Perfectly

selection for a gene that benefits the individual’s relatives

kin selection

How well did you know this?

Not at all

Perfectly

theory of evolution through the inheritance of acquired characteristics

Lamarckian evolution

How well did you know this?

Not at all

Perfectly

twins derived from one egg

monozygotic

How well did you know this?

Not at all

Perfectly

a heritable change in a DNA molecule

mutation

How well did you know this?

Not at all

Perfectly

a genetic inability to metabolize the amino acid phenylalanine

phenylketonuria (PKU)

How well did you know this?

Not at all

Perfectly

one that shows effects only in the homozygous condition

recessive

How well did you know this?

Not at all

Perfectly

helping others who may be helpful in return

reciprocal altruism

How well did you know this?

Not at all

Perfectly

a single-strand chemical

ribonucleic acid (RNA)

How well did you know this?

Not at all

Perfectly

gene that exerts its effects primarily in one sex because of activation by androgens or estrogens, although members of both sexes may have the gene

sex-limited genes

How well did you know this?

Not at all

Perfectly

genes on either the X or the Y chromosome

sex-linked genes

How well did you know this?

Not at all

Perfectly

Genes are chemicals that maintain their integrity from one generation to the next and influence the development of the individual. A dominant gene affects development regardless of whether a person has pairs of that gene or only a single copy per cell. A recessive gene affects development only in the absence of the dominant gene. True or False

True

Genes can change by mutations, microduplications, and microdeletions. True or False

True

Gene expression can also change in a process called epigenetics, as chemicals activate or deactivate parts of chromosomes. True or false

True

Most behavioral variations reflect the combined influences of genes and environmental factors. Heritability is an estimate of the amount of variation that is due to genetic variation as opposed to environmental variation. True or False

True

Researchers estimate heritability of a human condition by comparing monozygotic and dizygotic twins and by comparing adopted children to their biological and adoptive parents. They also identify genes that are more common in people with one type of behavior than another. True or false

True

Even if some behavior shows high heritability for a given population, a change in the environment might significantly alter the behavioral outcome. True or False

True

Genes influence behavior directly by altering brain chemicals and indirectly by affecting other aspects of the body and therefore the way other people react to us. True or False

True

The process of evolution through natural selection is a necessary outcome, given what we know about reproduction: Mutations sometimes occur in genes, and individuals with certain sets of genes reproduce more successfully than others do. True or False

True

The human brain has evolved to be as large as it is partly because we can provide a large amount of fuel to the brain. Human brains also have certain genes not active in other species. True or False

True

Evolution spreads the genes of the individuals who have reproduced the most. Therefore, if some characteristic is widespread within a population, it is reasonable to look for ways in which that characteristic is or has been adaptive. However, we cannot take it for granted that all common behaviors are the product of our genes. We need to distinguish genetic influences from learning. True or False

True

Suppose you have high sensitivity to tasting PTC. If your mother can also taste it easily, what (if anything) can you predict about your father’s ability to taste it?

If your mother has high sensitivity to the taste of PTC, we can make no predictions about your father. You may have inherited a high-sensitivity gene from your mother, and because the gene is dominant, you need only one copy of the gene to taste PTC.

Suppose you have high sensitivity to the taste of PTC. If your mother has low sensitivity, what (if anything) can you predict about your father’s taste sensitivity?

If your mother has low sensitivity, you must have inherited your high-sensitivity gene from your father, so he must have high sensitivity.

How does a sex-linked gene differ from a sex-limited gene?

A sex-linked gene is on the X or Y chromosome. A sex-limited gene is on an autosomal chromosome, but activated in one sex more than in the other.

Suppose someone identifies a “gene for” certain aspects of sexual development. In what ways might that statement be misleading?

Almost any characteristic depends on more than one gene, as well as influences from the environment.

How does an epigenetic change differ from a mutation?

A mutation is a permanent change in part of a chromosome. An epigenetic change is an increase or decrease in the activity of a gene or group of genes.

How does adding a methyl or acetyl group to a histone protein alter gene activity?

Adding a methyl group turns genes off. An acetyl group loosens histone’s grip and increases gene activation.

What are the main types of evidence to estimate the heritability of some behavior?

One type of evidence is greater similarity between monozygotic twins than dizygotic twins. Another is resemblance between adopted children and their biological parents. A third is a demonstration that a particular gene is more common than average among people who show a particular behavior.

Suppose someone determines the heritability of IQ scores for a given population. Then society changes in a way that provides the best possible opportunity for everyone within that population. Will heritability of IQ increase, decrease, or stay the same?

Heritability will increase. Heritability estimates how much of the variation is due to differences in genes. If everyone has the same environment, then differences in environment cannot account for much of the remaining differences in IQ scores. Therefore, the relative role of genetic differences will be greater.

What example illustrates the point that even if some characteristic is highly heritable, a change in the environment can alter it?

Keeping a child with the PKU gene on a strict low-phenylalanine diet prevents the mental retardation that the gene ordinarily causes. The general point is that sometimes a highly heritable condition can be modified environmentally.

Many people believe the human appendix is useless. Will it become smaller and smaller with each generation?

No. Failure to need a structure does not make it smaller in the next generation. The appendix will shrink only if people with a gene for a smaller appendix reproduce more successfully than other people do.

What are plausible ways for possible altruistic genes to spread in a population?

Altruistic genes could spread because they facilitate care for one’s kin or because they facilitate exchanges of favors with others (reciprocal altruism). Group selection may also work under some circumstances, especially if the cooperative group has some way to punish or expel an uncooperative individual.

In the control of behavior, genes are neither all important nor irrelevant. Certain behaviors have a high heritability, such as the ability to taste PTC. Many other behaviors are influenced by genes but also subject to strong influence by experience. Our genes and our evolution make it possible for humans to be what we are today, but they also give us the flexibility to change our behavior as circumstances warrant. True or False

True

Understanding the genetics of human behavior is important but also especially difficult, because researchers have such limited control over environmental influences and no control over who mates with whom. Inferring human evolution is also difficult, partly because we do not know enough about the lives of our ancient ancestors. Inferring behavioral evolution has the additional difficulty that behavior does not fossilize. True or False

True

remember that the way things are is not necessarily the same as the way they should be. For example, even if our genes predispose us to behave in a particular way, we can still decide to try to overcome those predispositions if they do not suit the needs of modern life. True or False

True

Genes can change by mutations, microduplications, and microdeletions. True or False

True

Gene expression can also change in a process called epigenetics, as chemicals activate or deactivate parts of chromosomes. True or False

True

Even if some behavior shows high heritability for a given population, a change in the environment might significantly alter the behavioral outcome. True or False

True

Genes influence behavior directly by altering brain chemicals and indirectly by affecting other aspects of the body and therefore the way other people react to us. True or False

True

The human brain has evolved to be as large as it is partly because we can provide a large amount of fuel to the brain. Human brains also have certain genes not active in other species. True or false

True

Suppose you have high sensitivity to the taste of PTC. If your mother also has high sensitivity, what (if anything) can you predict about your father’s taste sensitivity?

We do not have enough information to make a prediction.

Suppose you have high sensitivity to the taste of PTC. If your mother has low sensitivity, what (if anything) can you predict about your father’s taste sensitivity?

He has high taste sensitivity.

What is a sex-limited gene?

A gene that sex hormones activate

Suppose someone identifies a “gene for” certain aspects of sexual development. In what ways might that statement be misleading?

Almost any characteristic depends on many genes, as well as influences from the environment.

How does an epigenetic change differ from a mutation?

An epigenetic change is an alteration of gene activity without structurally replacing any part of the gene itself.

How does adding a methyl or acetyl group to a histone protein alter gene activity?

A methyl group turns genes off. An acetyl group loosens histone’s grip and increases gene activation.

Which of the following is NOT one of the main types of evidence to estimate the heritability of some behavior?

Comparisons of people living in different cultures

Heritability will increase.

The information about phenylketonuria (PKU) supports which of these conclusions? Several genes active in the human brain are not found in other species. Each brain area controls a different behavioral function. A change in the environment can alter the effects of a gene. Epigenetic changes depend on methyl and acetate groups.

A change in the environment can alter the effects of a gene.

What, if anything, can we predict about the future of human evolution? Answer

People will become more like whichever people tend to have the most children.

Which of these is the least acceptable explanation for how an altruistic gene might spread in a population?

Selection for genes that benefit the species

a programmed mechanism of cell death

apoptosis

to develop the axon and dendrites that give a neuron its distinctive properties

differentiates

a condition resulting from prenatal exposure to alcohol and marked by hyperactivity, impulsiveness, decreased alertness, varying degrees of mental retardation, motor problems, heart defects, and facial abnormalities

fetal alcohol syndrome

(musician’s cramp) a disorder where one or more fingers is in constant contraction or where moving one finger independently of others is difficult

focal hand dystonia

movement of brain neurons or glia

migrate

process by which glia produce the insulating fatty sheaths that accelerate transmission in many vertebrate axons

myelination

a protein that promotes the survival and growth of axons in the sympathetic nervous system and certain axons in the brain

nerve growth factor (NGF)

a chemical that promotes the survival and activity of neurons

neurotrophin

production of new cells

proliferation

undifferentiated cells that divide and produce daughter cells that develop more specialized properties

stem cells

formation of synapses

synaptogenesis

In vertebrate embryos, the central nervous system begins as a tube surrounding a fluid-filled cavity. Developing neurons proliferate, migrate, differentiate, myelinate, and generate synapses. Neuron proliferation varies among species mainly by the number of cell divisions. Migration depends on a large number of chemicals that guide immature neurons to their destinations. True or False

True

In adult vertebrates, new neurons can form in the olfactory system, the hippocampus, and the song-producing brain areas of some bird species. Adult humans form new neurons in the hippocampus but few or none in the olfactory bulbs or cerebral cortex. True or False

True

Growing axons find their way close to the right locations by following chemicals. Then they array themselves over a target area by following chemical gradients. True or False

True

After axons reach their targets based on chemical gradients, the postsynaptic cell adjusts the connections based on experience, accepting certain combinations of axons and rejecting others. This kind of competition among axons continues throughout life. True or False

True

Initially, the nervous system develops far more neurons than will actually survive. Axons of the sympathetic nervous system survive only if they reach a target cell that releases to them nerve growth factor. Otherwise, they die in a process called apoptosis. Apoptosis also occurs in the brain, but the factors controlling it are poorly understood. True or False

True

The developing brain is vulnerable to chemical insult. Many chemicals that produce only mild, temporary problems for adults can permanently impair early brain development. True or False

True

At an early stage of development, the cortex is sufficiently plastic that visual input can cause what would have been the auditory cortex to develop different properties and now respond visually. True or False

True

Enriched experience leads to greater branching of axons and dendrites, partly because animals in enriched environments are more active than those in deprived environments. True or False

True

Specialized experiences can alter brain development, especially early in life. For example, in people who are born blind, representation of touch and hearing expands in areas usually reserved for vision. True or False

True

Extensive practice of a skill expands the brain’s representation of sensory and motor information relevant to that skill. For example, the representation of fingers expands in people who regularly practice musical instruments. True or False

True

Controversy remains about whether new adult experiences modify brain structures enough to be visible in MRI scans. True or False

True

Although expanded representation in the brain is ordinarily a good thing, it can be harmful if carried too far. Some musicians and others who use their hands many hours each day develop brain changes that interfere with their ability to feel or use one finger independently of the others. True of False

True

Compared to adults, adolescents tend to be impulsive and centered more on present pleasures than future prospects. Although immaturity of the prefrontal cortex contributes to impulsiveness, impulsiveness occurs mostly under the influence of peer pressure. True or False

True

On average, people in old age show declining memory and reasoning, and shrinkage of certain brain areas. However, these averages do not apply to all individuals or all situations. Many older people compensate for inefficiency of certain brain functions by recruiting activity in additional brain areas. True or False

True

Which develops first, a neuron’s axon or its dendrites?

The axon forms first.

New receptor neurons form in adult rodents for which sensory system?

Olfaction

What evidence indicated that new neurons seldom or never form in the human cerebral cortex and olfactory bulb?

The 14C concentration in the DNA of human neurons in the cerebral cortex and olfactory bulbs corresponds to the level during the year the person was born, indicating that all or nearly all of those neurons are as old as the person is.

What was Sperry’s evidence that axons grow to a specific target instead of attaching at random?

If he cut a newt’s eye and inverted it, axons grew back to their original targets, even though the connections were inappropriate to their new positions on the eye.

If axons from the retina were prevented from showing spontaneous activity during early development, what would be the probable effect on development of the thalamus?

The axons would attach based on a chemical gradient but could not fine-tune their adjustment based on experience. Therefore, the connections would be less precise.

What process assures that the spinal cord has the right number of axons to innervate all the muscle cells?

The nervous system builds far more neurons than it needs and discards through apoptosis those that do not make lasting synapses.

What class of chemicals prevents apoptosis in the sympathetic nervous system?

Neurotrophins, such as nerve growth factor

At what age does a person have the greatest number of neurons—early in life, during adolescence, or during adulthood?

The neuron number is greatest early in life.

Anesthetic drugs and anxiety-reducing drugs increase activity of GABA, decreasing brain excitation. Why would we predict that exposure to these drugs might be dangerous to the brain of a fetus?

Prolonged exposure to anesthetics or anxiety-reducing drugs might increase apoptosis of developing neurons. Increased GABA activity decreases excitation, and developing neurons undergo apoptosis if they do not receive enough excitation. Many studies confirm that anesthetics and anxiety-reducing drugs impair brain development in laboratory animals, although the research is less complete for humans (Sanders, Hassel, Davidson, Robertson, & Ma, 2013; C. Young et al., 2005).

In the ferret study, how did the experimenters determine that visual input to the auditory portions of the brain actually produced a visual sensation?

They trained the ferrets to respond to stimuli on the normal side, turning one direction in response to sounds and the other direction to lights. Then they presented light to the rewired side and saw that the ferret again turned in the direction it had associated with lights.

An enriched environment promotes growth of axons and dendrites in laboratory rodents. What is known to be one mportant reason for this effect?

Animals in an enriched environment are more active, and their exercise enhances growth of axons and dendrites.

Name two kinds of evidence indicating that touch information from the fingers activates the occipital cortex of people blind since birth.

First, brain scans indicate increased activity in the occipital cortex while blind people perform tasks such as feeling two objects and saying whether they are the same or different. Second, temporary inactivation of the occipital cortex blocks blind people’s ability to perform that task, without affecting the ability of sighted people.

Which brain area shows expanded representation of the left hand in people who began practicing stringed instruments in childhood and continued for many years? Answer

Somatosensory cortex (postcentral gyrus) of the right hemisphere.

What change in the brain is responsible for musician’s cramp?

Extensive practice of violin, piano, or other instruments causes expanded representation of the fingers in the somatosensory cortex, as well as displacement of representation of one or more fingers in the motor cortex. If the sensory representation of two fingers overlaps too much, the person cannot feel them separately or move them separately.

Under what circumstances are adolescents most likely to make an impulsive decision?

Adolescents are most likely to make an impulsive decision in the presence of peer pressure.

When people claim that adolescents make risky decisions because of a lack of inhibition, which brain area do they point to as being responsible for inhibition?

The prefrontal cortex

What is one way in which older adults compensate for less efficient brain functioning?

Many of them compensate by activating additional brain areas.

True

Growing axons find their way close to the right locations by following chemicals. Then they array themselves over a target area by following chemical gradients. True or false

True

The developing brain is vulnerable to chemical insult. Many chemicals that produce only mild, temporary problems for adults can permanently impair early brain development. True or False

True

Enriched experience leads to greater branching of axons and dendrites, partly because animals in enriched environments are more active than those in deprived environments. True or False

True

Controversy remains about whether new adult experiences modify brain structures enough to be visible in MRI scans. True or False

True

Which part of a neuron forms first, if either?

The axon forms first.

What is unusual about the olfactory receptors?

We continue forming new olfactory neurons throughout life.

The 14C concentration in the atmosphere has been declining since 1963. The concentration in neurons of a person’s cerebral cortex and olfactory bulbs corresponds to that of.

the year of the person’s birth

When Sperry cut a newt’s optic nerve and turned the eye upside down, what happened?

Axons of the optic nerve grew back to their original targets.

If axons from the retina were prevented from showing spontaneous activity during early development, what would be the probable effect on development of the thalamus?

Axons would not fine-tune their adjustment based on experience, so their connections would be less precise.

Why does the spinal cord have the right number of axons to innervate all the muscle cells?

The spinal cord makes an excess of neurons, but those that fail to innervate a muscle die.

What is apoptosis?

A programmed mechanism of cell death

Which neurons depend on nerve growth factor to prevent apoptosis in early development?

Neurons in the sympathetic nervous system

At what age does a person have the largest number of neurons?

Before or shortly after birth

If a pregnant woman drinks alcohol, alcohol harms the brain of the fetus not only while it is in the system, but also while it is washing away after drinking. What is the danger while alcohol is washing away?

Overstimulation at glutamate synapses can poison the mitochondria.

In the ferret study, what evidence indicated that visual input to the auditory portions of the brain actually produced a visual sensation?

Ferrets that learned to turn one way in response to light in the normal eye turned the same way to light in the rewired eye.

An enriched environment promotes growth of axons and dendrites in laboratory rodents. What is known to be one important reason for this effect?

Increased physical activity

If a person is born blind, in what way do the senses of hearing and touch improve?

Through practice the person learns to increase attention to hearing and touch, and those sensations come to activate the occipital cortex.

Of the following, which is the strongest evidence to indicate that musical training modifies brain anatomy? The gray matter of several cortical areas is thicker in professional musicians than in nonmusicians. A larger than average portion of the right somatosensory cortex responds to the left hand in stringed instrument players than in other people. At age 6, children starting musical training did not differ from average, but 15 months later they showed enlargements of several brain areas.

At age 6, children starting musical training did not differ from average, but 15 months later they showed enlargements of several brain areas.

Many studies report brain changes after special experiences in adulthood, such as learning to juggle or learning to play golf. Why are some researchers skeptical of these findings?

Most of the reported results were small and have not been replicated.

What causes musician’s cramp?

Rewiring of the cerebral cortex

Is it reasonable to argue that adolescents are mature enough to make some decisions and not others?

Perhaps. Adolescents reason in an immature way when they decide quickly under peer pressure.

Immaturity of the prefrontal cortex is a possible explanation for which aspect of adolescent behavior?

impulsivity

Why do many older people continue to hold important jobs in spite of the declines in memory and brain function that are known to occur in old age?

The declines on average do not apply to all people.

In an unmodified newt brain, the dorsal pathway from the retina leads to the __________ area of the tectum.

lateral

Based on your research, you can conclude that the dorsal pathway from the retina, after modification, now leads to the __________ area of the tectum.

medial

In the modified newt brain, the ventral pathway from the retina now leads to the _________ area of the tectum.

lateral