Deck 5: Genetics and the Development of the Human Brain

Question 1

Which of the following is the best example of a phenotype?

A) Ryan has black hair.
B) Jessica has an allele for type O blood from her father and one for type A blood from her mother.
C) Andrew has one gene for blonde hair and another gene for black hair.
D) Elizabeth has two copies of the APOE³ allele.

Answer 1

Ryan has black hair.

Question 2

A person's phenotype represents

A) genetic influences,but not environmental influences.
B) environmental influences,but not genetic influences.
C) neither environmental nor genetic influences.
D) an interaction between genetic and environmental influences.

Answer 2

an interaction between genetic and environmental influences.

Question 3

DNA is located in

A) chromosomes only.
B) mitochondria only.
C) chromosomes and in mitochondria.
D) neither chromosomes nor mitochondria.

Answer 3

chromosomes and in mitochondria.

Question 4

The historical migration patterns of humans may be traced by analyzing mutations in

A) mitochondrial DNA inherited from the mother.
B) mitochondrial DNA inherited from the father.
C) mitochondrial DNA inherited from both parents.
D) DNA located on the X chromosome.

Question 5

Brandon and Jacob are identical twins.However,Brandon had a finger damaged in an accident,so even if you couldn't tell them apart from a distance,once you saw the finger you knew who was who.This difference is a characteristic of their

A) genotype.
B) personality.
C) heterozygous chromosomes.
D) phenotype.

Question 6

Which of the following is the best example of a genotype?

A) Nicole has green eyes.
B) Justin is taller than his parents.
C) Lauren has the same hair color as her fraternal twin sister.
D) Anthony has two copies of the APOE² allele.

Question 7

The complete set of instructions for constructing a human being is known as the human

A) genome.
B) genotype.
C) phenotype.
D) chromosome.

Question 8

How many chromosomes do human beings receive from each parent?

A) 23
B) 46
C) 21
D) 42

Question 9

How many chromosomes do human beings typically have?

A) 20 pairs for a total of 40 chromosomes
B) 21 pairs for a total of 42 chromosomes
C) 22 pairs for a total of 44 chromosomes
D) 23 pairs for a total of 46 chromosomes

Question 10

A person's observable characteristics,representing a combination of her or his genes and environmental influences,are known as the person's

A) genome.
B) genotype.
C) phenotype.
D) chromosome.

Question 11

Gene expression refers to the

A) division of the chromosomes in half during the formation of eggs and sperm.
B) passing along of genes that are located close to one another on a chromosome.
C) conversion of genetic instructions into a feature of a living cell.
D) imprinting of particular genes.

Question 12

The field of behavioral genetics investigates

A) evidence for the evolution of physical traits.
B) changes in an individual's genome due to aging.
C) the migration of human species out of Africa.
D) the connections between genes and behavior.

Question 13

Which of the following is the best definition of a gene?

A) an individual's set of observable characteristics
B) a segment of DNA that contains instructions for producing a protein
C) a molecule that encodes genetic information
D) a sequence of three bases on the DNA molecule that encode one of twenty amino acids

Question 14

An allele that produces a phenotypical trait regardless of whether or not its pair is homozygous or heterozygous is

A) imprinted.
B) dominant.
C) recessive.
D) an SNP.

Question 15

We inherit our mitochondrial DNA from

A) our fathers only.
B) our mothers only.
C) both parents in equal amounts.
D) both parents,but about two-thirds from our mother and one-third from our father.

Question 16

Forensic scientists prefer which of the following methods for identifying human remains?

A) an analysis of chromosomal DNA inherited from both parents
B) an analysis of chromosomal DNA inherited from the mother
C) an analysis of mitochondrial DNA inherited from the mother
D) an analysis of mitochondrial DNA inherited from the father

Question 17

An individual's set of genetic instructions is known as the individual's

A) genome.
B) genotype.
C) phenotype.
D) chromosome.

Question 18

Different versions of the same gene are known as

A) SNPs.
B) imprinted genes.
C) alleles.
D) proteomes.

Question 19

Robert and Megan are brother and sister,and both have type O blood.They know that their mother has type A blood,but they don't know their father's blood type.Using what they know about their own blood types and their mother's,they know that their father's blood type

A) could be A,B,O,or AB.
B) must be O.
C) must be A.
D) could be A,B,or O.

Question 20

Which of the following is the best definition of the human genome?

A) The complete genetic composition of a human being.
B) An individual's observable characteristics that are not due to environmental factors.
C) The translation of the genotype into the phenotype of an organism.
D) A functional hereditary unit made up of DNA that occupies a fixed location on a chromosome.

Question 21

The proteome is defined as

A) the set of proteins encoded and expressed by the genome.
B) the set of proteins encoded by an individual's genotype.
C) the rate of gene expression.
D) a species' profile of mitochondrial DNA.

Question 22

Cystic fibrosis is a fatal lung condition that results from a recessive gene.If one parent is a healthy carrier for the condition while the other is not a carrier,what is the likely outcome for any children they might have?

A) The children will be heterozygous for cystic fibrosis,and all will develop the disease.
B) Fifty percent of their children will develop the disease,and the other fifty percent will be carriers.
C) None of the children will have the disease,and none will be carriers.
D) None of the children will have the disease,but they have a fifty percent chance of becoming carriers.

Question 23

Which of the following accurately describes the attraction of bases between strands of DNA?

A) A pairs with T,and C pairs with G
B) A pairs with C,and T pairs with G
C) A pairs with G,and T pairs with C
D) A pairs with U,and T pairs with G

Question 24

Most cases of colorblindness result from abnormal recessive genes located on the X chromosome that are not duplicated on the Y chromosome.Which of the following statements accurately predicts the outcome for the children of a father with typical genes and a mother with abnormal genes?

A) Half of the couple's daughters,but none of their sons,are likely to be colorblind.
B) Half of the couple's sons,but none of their daughters,are likely to be colorblind.
C) None of the couple's children are likely to be colorblind.
D) All of the couple's children are likely to be colorblind.

Question 25

A group of three bases that provides instructions for the production of a single amino acid is known as a

A) proteome.
B) gene.
C) ribosome.
D) codon.

Question 26

Mutations

A) always have negative outcomes.
B) always have positive outcomes.
C) can have positive,negative,or neutral outcomes.
D) have neither positive nor negative outcomes,because they are always recessive.

Question 27

The complexity of human beings relative to other animals is probably a result of

A) the humans' higher number of genes.
B) the rate of human gene expression,particularly in the brain.
C) the rate of human gene expression,particularly in the liver and blood.
D) humans' larger numbers of imprinted genes.

Question 28

You were recently introduced to your roommate's sibling.To your surprise,even though the siblings are the same sex,they look nothing alike.Which of the following is the best explanation of this situation?

A) They must have different parents,as genetic inheritance ensures that they share a significant number of genes.
B) Although they started out very similar genetically,their genotypes have changed during development to make them look very different.
C) Given the number of different combinations of genes possible during reproduction,it may be that the two siblings don't really share many genes.
D) One has expressed only recessive genes,while the other has not.

Question 29

The passing along of genes that are physically close to one another on the same chromosome is known as

A) linkage.
B) crossing over.
C) meiosis.
D) gene expression.

Question 30

_________ of the genes found on the X chromosome are duplicated on the Y chromosome.

A) All
B) None
C) Most
D) Some

Question 31

Sarah's mother has Huntington's disease,an illness that results from a dominant gene,but her father does not.What is the likelihood that Sarah herself will develop the disease?

A) Sarah has no chance of developing the disease,as she would have inherited a healthy allele from her father.
B) Sarah probably has a 50 percent chance of developing the disease,as her mother could have given her either a healthy allele or an allele that produces the illness.
C) Sarah has a 50 percent chance of developing the disease,because her mother would not have the disease herself unless she were homozygous for Huntington's disease.
D) Sarah has a 25 percent chance of developing the disease,because her father could be a carrier.

Question 32

When either a mother's or father's version of a gene is expressed,but not both,we refer to the gene as

A) imprinted.
B) dominant.
C) recessive.
D) an SNP.

Question 33

Which of the following statements about the genetic makeup of humans is true?

A) Our genetic makeup is very different from every other animal on earth.
B) Our genes are what make all humans similar,but it is also our genes that make us all different from each other.
C) We share an identical genetic code with old-world apes-it is just the expression of alleles that makes us human and able to speak.
D) The DNA of all humans is similar,but the DNA of other animals is different.

Question 34

A characteristic that results from genes on the X chromosome that are not duplicated on the Y chromosomes is referred to as being

A) recessive.
B) a mutation.
C) a SNP.
D) sex-linked.

Question 35

Huntington's disease,a fatal degenerative movement disorder,results from large numbers of codon repeats in the Huntington gene located on chromosome 4.This means that the

A) extra codon repeats will not impact the individual's phenotype.
B) affected Huntington gene will be silenced,producing no protein.
C) affected Huntington gene will produce a protein with abnormally large amounts of the amino acid encoded by the extra codons.
D) affected Huntington gene will produce a protein with abnormally small amounts of the amino acid encoded by the extra codons.

Question 36

The human proteome is

A) the same as the proteomes of other primates.
B) the same as the proteomes of other mammals.
C) the same as the proteomes of all living things.
D) unique to our species.

Question 37

Gene expression

A) is identical in all body cells.
B) occurs at the same rate in all mammals.
C) occurs at the same rate in all living things.
D) differs between species and in different types of cells.

Question 38

A single human can produce eggs or sperm with more than _________ different combinations of his or her chromosomes.

A) 800
B) 8,000
C) 800,000
D) 8,000,000

Question 39

The process in which genes exchange equivalent sections of genetic material is known as

A) linkage.
B) crossing over.
C) meiosis.
D) gene expression.

Question 40

Nancy and Cliff had four children who did not have cystic fibrosis,but their fifth child was born with the disease.Cystic fibrosis is carried on a recessive gene.Given what you've learned in this chapter,how could this happen?

A) It wasn't until the fifth child that both parents passed on the allele for this illness.
B) Recessive genes normally skip a generation,but after the parents had five children,the gene was expressed.
C) Their fifth child must have been a boy,which makes it more probable that he would have the illness.
D) Their fifth child must have been a girl,which makes it more probable that she would have the illness.

Question 41

Amber and Rachel are identical twins who were raised together,and Nicole and Kayla are identical twins who were adopted by different families at birth.Based on the findings of the Minnesota Study of Twins Raised Apart,what can we expect to see as these girls grow up?

A) Amber and Rachel will be have more similar nonreligious social attitudes than Nicole and Kayla.
B) Amber and Rachel will show about the same similarities in their nonreligious social attitudes as Nicole and Kayla.
C) Amber and Rachel will show less similarity in their nonreligious social attitudes than Nicole and Kayla.
D) None of the twins will share any substantial similarities in nonreligious social attitudes with her twin.

Question 42

Kyle plants a group of seeds in a pot of enriched soil,and provides all the seeds with identical temperature,lighting,and water.When his plants are mature,he notices that they are quite different in height.Which of the following is the best conclusion Kyle could draw from his observations?

A) The differences in the height of his plants are due to equal contributions of environmental and genetic variables.
B) Holding the plants' environment constant has magnified the influence of genetic differences on the height of the plants.
C) Genetic variables are more influential than environmental variables in determining the height of Kyle's plants.
D) Kyle lacks sufficient information to draw any scientific conclusions from his observations.

Question 43

A recessive gene

A) is never expressed.
B) can influence a genotype,but not a phenotype.
C) can influence the phenotype of female children,but not male children.
D) can influence a phenotype when it occurs in pairs or on the X chromosome.

Question 44

Research has shown that a person's height is about 81 percent heritable,whereas his or her body mass index (BMI)is about 59 percent heritable.Which of the following is the most accurate interpretation of these findings?

A) The variability we see in a population's height is more influenced by genetic factors than the variability we see in the population's weight.
B) Environmental factors account for only 19 percent of a person's height and 41 percent of a person's BMI.
C) We cannot make any conclusions about genetic contributions to either height or weight.
D) Knowing the relative genetic contributions to traits such as height or weight does not allow us to compare these two unrelated characteristics of people.

Question 45

The Minnesota Study of Twins Raised Apart found support for which of the following conclusions?

A) Identical twins are very similar to each other on a number of traits,regardless of whether a trait is highly correlated or not.
B) Identical twins raised together are very similar to each other on a number of traits,but identical twins raised apart are not.
C) Identical twins are very similar on traits that are highly correlated,like fingerprint ridges,but not similar to each other on traits that are not highly correlated,like nonreligious social attitudes.
D) Identical twins are no more similar to each other on highly correlated traits than fraternal twins and non-twin siblings.

Question 46

For the first two weeks of a human pregnancy,the developing organism is referred to as a(n)

A) zygote.
B) embryo.
C) blastocyst.
D) fetus.

Question 47

In the third through eighth weeks of a human pregnancy,the developing organism is referred to as a(n)

A) zygote.
B) embryo.
C) blastocyst.
D) fetus.

Question 48

Queen Victoria of England had a son,Leopold,and a great-grandson,Tsarevich Alexei Nikolaevich Romanov of Russia,who had hemophilia.We can conclude that:

A) Queen Victoria must have had hemophilia,too.
B) Queen Victoria was a carrier for hemophilia.
C) Queen Victoria's husband,Prince Albert,must have been a carrier.
D) Leopold and Tsarevich Alexei probably developed hemophilia due to a spontaneous mutation,because their female relatives did not have the condition.

Question 49

Tom's father has hemophilia,but Tom does not have the disease.What are the chances that Tom's children will have hemophilia?

A) Tom's sons will almost certainly have it because Tom will have inherited the recessive gene from this father.
B) Tom's daughters may be carriers,but his sons will not have the gene.
C) All of Tom's children will be carriers,but it will not be expressed until they have children.
D) None of Tom's children will be carriers or have the illness because his X gene came from his mother,who is not a carrier.

Question 50

In the Minnesota Study of Twins Reared Apart,identical twins were found to be

A) very similar in all characteristics studied,regardless of whether they were raised together or apart.
B) similar in some characteristics studied,but not all,regardless of whether they were raised together or apart.
C) similar in all characteristics studied only if they were raised together.
D) similar in some characteristics studied,but not all,only if they were raised together.

Question 51

In 1875,Charles Darwin reported on a family group living in what is now Pakistan that had a condition known as ectodermal dysplasia,which results in few teeth and inactive sweat glands.Darwin wrote that "…no instance has occurred of a daughter being affected...though the daughters in the above family are never affected,they transmit the tendency to their sons: and no case has occurred of a son transmitting it to his sons.The affection thus appears only in alternate generations,or after long intervals." The most likely explanation of Darwin's observations is that ectodermal dysplasia

A) results from spontaneous mutations.
B) is a sex-linked condition.
C) results from x-inactivation.
D) probably has environmental,as opposed to genetic causes.

Question 52

During early development,the nervous system develops from which germ layer?

A) the endoderm
B) the mesoderm
C) the ectoderm
D) the blastoderm

Question 53

"Extreme skewing" in x-inactivation has been linked with which of the following characteristics in offspring?

A) hemophilia
B) colorblindness
C) Alzheimer's disease
D) sexual orientation

Question 54

Calico cats with two sex chromosomes

A) can be male or female.
B) are almost always male,because the calico condition is sex-linked.
C) are always female,because the calico condition results from x-inactivation.
D) are the result of spontaneous mutations that do not affect the sex chromosomes.

Question 55

Connective tissue,muscles,blood vessels,and bone develop from which germ layer?

A) the endoderm
B) the mesoderm
C) the ectoderm
D) the blastoderm

Question 56

Compared with non-twin siblings,fraternal twins

A) experience the same level of genetic and environmental influence.
B) have more genes in common.
C) have fewer environmental influences in common.
D) have more environmental influences in common.

Question 57

A process that prevents the production of much higher amounts of protein in females than in males is known as

A) X inactivation.
B) imprinting.
C) crossing over.
D) linkage.

Question 58

When variations in a single base are responsible for the difference between two alleles,the resulting condition is known as

A) X inactivation.
B) an imprinted gene.
C) a SNP.
D) a mutation.

Question 59

In their study of the heritability of autistic traits among Dutch teens,Rosa Hoekstra and her colleagues were careful to choose participants from a variety of backgrounds and circumstances.Why is careful sampling especially important to studies of heritability?

A) The effects of heritability are most obvious in populations that exclude extreme environmental conditions,such as affluent or very poor families.
B) Environmental influences are magnified in extreme environmental conditions,such as among affluent or very poor families.
C) Extremes of environmental conditions,such as affluent or very poor families,tend to magnify the influence of heritability.
D) These precautions are really not relevant,because heritability cannot be assessed experimentally.

Question 60

Different versions of the APOE gene are correlated with the development of

A) hemophilia.
B) colorblindness.
C) breast cancer.
D) Alzheimer's disease.

Question 61

The interior of the neural tube will be retained in the adult brain as the

A) forebrain.
B) ventricles and central canal.
C) hindbrain.
D) corpus callosum.

Question 62

Organization of the dorsal neural tube into sensory systems is influenced by

A) sonic hedgehog.
B) BMP.
C) hox genes.
D) guidepost cells.

Question 63

At the peak of neurogenesis in humans,about how many new neural cells are produced per minute?

A) 10,000
B) 75,000
C) 250,000
D) 500,000

Question 64

Ectoderm cells that do not differentiate into nervous system tissue will become

A) muscle and bone.
B) connective tissue.
C) skin.
D) internal organs.

Question 65

During which stage of development do new neurons form connections with other neurons?

A) neurogenesis
B) apoptosis
C) differentiation
D) the formation of synapses

Question 66

Sonic hedgehog is secreted by the

A) radial glia.
B) notochord.
C) substantia nigra.
D) ventricular zone.

Question 67

New cells formed at the ventricular zone begin to migrate after the _________ following conception.

A) seventh day
B) seventh week
C) fifth month
D) seventh month

Question 68

Neural tissue results when inducing factors

A) block the action of BMP.
B) promote the action of BMP.
C) block the action of sonic hedgehog.
D) promote the action of sonic hedgehog.

Question 69

Cells in the outer layers of the cerebral cortex are the ___________ to begin migrating,and they have the _____________ journey to their final destination.

A) first;shortest
B) first;longest
C) last;shortest
D) last;longest

Question 70

During migration,most neurons are guided to their ultimate location by

A) the ventricular zone.
B) radial glia.
C) oligodendrocytes.
D) The formation of synapses.

Question 71

Organization of the ventral neural tube into a motor system is primarily the result of

A) sonic hedgehog.
B) BMP.
C) hox genes.
D) guidepost cells.

Question 72

Some researchers have found disorganization of cells in the hippocampus in some schizophrenics.Which of the following is the most likely inference based on this finding?

A) Because the organization of cells occurs before birth,schizophrenia cannot be blamed on childrearing practices.
B) There must be a single gene that has caused this error in development.
C) The hippocampus must be responsible for the hallucinations some schizophrenics have.
D) We can expect that persons with poor prenatal care are more apt to have schizophrenic children.

Question 73

Internal organs develop from which germ layer?

A) the endoderm
B) the mesoderm
C) the ectoderm
D) the blastoderm

Question 74

This figure illustrates which of the following processes?

A) Migrating cells follow radial glia from the ventricular zone to the developing cortex.
B) Progenitor cells located in the ventricular zone produce daughter cells that remain in the ventricular zone or migrate.
C) Developing axons adhere to cell adhesion chemicals on the surface of other cells on route to forming synapses with target cells.
D) Guidepost cells release chemicals that either attract or repel growing axons.

Question 75

Which of the following is an inducing factor?

A) notochord
B) hox
C) cell adhesion molecules
D) bone morphogenetic protein (BMP)

Question 76

Progenitor cells that divide to produce another progenitor cell and a migrating cell divide _________________ along a cleavage line that is ________________to the surface of the ventricular zone.

A) symmetrically;perpendicular
B) symmetrically;parallel
C) asymmetrically;perpendicular
D) asymmetrically;parallel

Question 77

The neural plate develops along the _________ midline from cells in the _________.

A) dorsal;ectoderm
B) dorsal;mesoderm
C) ventral;ectoderm
D) ventral;endoderm

Question 78

The notochord will eventually develop into the

A) ventricles and central canal.
B) ventral motor system of the spinal cord.
C) the vertebrae surrounding the spinal cord.
D) the dorsal sensory system of the spinal cord.

Question 79

Cells that develop into neurons and glia originate in the

A) ventricular zone.
B) radial glia.
C) forebrain.
D) spinal cord.

Question 80

Which of the following statements about radial glia is true?

A) They degenerate when migration is complete.
B) They differentiate into astrocytes.
C) They retain the ability to produce daughter cells.
D) They differentiate into neurons.