Science Homework Help

Science Homework Help. Please answer all multiple choice questions and others write question about biology 1

Polyploidy is the:

	a.	presence of multiple sets of chromosomes.
	b.	general term for conditions such as Down or Turner syndrome.
	c.	presence of more than two of a certain chromosome.
	d.	presence of one extra chromosome.
	e.	presence of only one of each chromosome.

Nearly half of the pregnancies that end in miscarriage have:

	a.	Down syndrome.
	b.	major chromosomal abnormalities.
	c.	Klinefelter syndrome.
	d.	homozygosity for a recessive lethal allele.
	e.	trisomy of chromosome 21.

Gene therapy involves:

	a.	repairing mutant alleles in certain body cells.
	b.	replacing all mutant alleles in body cells.
	c.	improving gene expression in key body cells.
	d.	replacing poor copies of alleles with normal alleles.
	e.	replacing a mutant allele in certain body cells with a normal allele.

Human genetics can be most effectively studied using:

	a.	offspring raised under controlled conditions.
	b.	experimental matings between true-breeding strains.
	c.	controlled matings.
	d.	population studies of large extended families.
	e.	population studies of small extended families.

Autosomal aneuploidies arise by:

	a.	errors in crossing-over.
	b.	chromosome breakage and rejoining.
	c.	mistakes in chromosome replication.
	d.	meiotic nondisjunction.
	e.	mitotic nondisjunction.

In a chromosomal inversion, a segment of a chromosome is:

	a.	reversed.
	b.	duplicated.
	c.	lost.
	d.	attached to a nonhomologous chromosome.
	e.	deleted

A couple in which the woman is homozygous dominant for clotting ability and the man has hemophilia A will produce:

	a.	carrier daughters and normal sons.
	b.	offspring of unknown genotype for this gene.
	c.	affected daughters and affected sons.
	d.	carrier daughters and affected sons.
	e.	normal daughters and normal sons.

Match the term with the corresponding condition..

	Jacobsen syndrome, in which part of chromosome 11 is missing
	Philadelphia chromosome, in which parts of chromosomes 9 and 22 switch places; strongly associated with chronic myelogenous leukemia
	de la Chapelle syndrome, in which an unequal crossing over event between the X and Y chromosomes during spermatogenesis results in the transfer of part of the Y chromosome to the X chromosome, resulting in an XX male
	in some severe hemophilia A patients, a region in the factor VIII gene is reversed

a.	translocation
b.	deletion
c.	inversion
d.	fragile site
e.	genomic imprinting
f.	insertion
g.	reciprocal translocation

Hemophilia A is an example of a(n) _____ disease and is characterized by a lack of blood-clotting factor ____.

	a.	X-linked; VIII
	b.	sex-linked recessive; V
	c.	autosomal dominant; VIII
	d.	autosomal recessive; VIII
	e.	sex-linked dominant; V

Geneticists study pedigrees in order to predict how traits determined by phenotype are inherited from one generation to the next.
_________________

True

False

Maternal PKU can result in serious effects in fetuses. This problem occurs because:

	a.	the fetus is usually homozygous dominant and therefore has PKU.
	b.	the mother is homozygous dominant for PKU and cannot metabolize phenylalanine.
	c.	the mother is homozygous recessive for PKU and cannot metabolize phenylalanine.
	d.	the fetus is homozygous for PKU and therefore cannot metabolize phenylalanine.
	e.	the mother is heterozygous for PKU and therefore cannot metabolize phenylalanine.

Make a sketch showing how nondisjunction in meiosis can result in Down syndrome

Down syndrome is characterized by:

	a.	the presence of 47 chromosomes per somatic cell.
	b.	increasing risk with younger maternal age.
	c.	the presence of an extra chromosome 18 in each somatic cell
	d.	single base mutations.
	e.	the same symptoms observed in each individual.

A fragile site:

	a.	is found only on the X chromosome.
	b.	occurs in only one of the sister chromatids.
	c.	is associated with cancerous cells.
	d.	is usually not inherited.
	e.	is the result of genomic imprinting.

Karyotyping is useful for determining:

	a.	the number of chromosomes in an individual.
	b.	whether or not gene mutations have occurred.
	c.	the presence of sickle cell anemia.
	d.	whether or not a specific gene is missing from a chromosome.
	e.	the presence of recessive traits.

In fragile X syndrome, the fragile X gene contains a nucleotide triplet that repeats 200-1000 times.

True

False

An individual who inherits the specific chromosome ____ deletion from his/her ____ will most likely have Prader-Willi syndrome rather than Angelman syndrome.

	a.	15; mother
	b.	15; father
	c.	21; mother
	d.	21; father
	e.	12; father

Genome-wide association scans compare the proteins of individuals with a particular disease to individuals without the disease.
_________________

True

False

A genetic counselor will know that the probability of having a child affected with a condition inherited as an autosomal recessive would be:

	a.	0.25 or 25% if both parents were homozygous normal.
	b.	0.5 or 50% if both parents were heterozygous.
	c.	0% if both parents were heterozygous.
	d.	0.25 or 25% if both parents were heterozygous.
	e.	0.5 or 50% if both parents were homozygous normal.

In trisomy 21, while all genetic information is intact, a(n) abnormal copy of this chromosome creates a genetic imbalance which causes abnormal physical and mental development.
_________________

True

False

Males with Klinefelter syndrome lack a Barr Body.
_______________

True

Fals

In genomic imprinting:

	a.	a gene is imprinted in the progeny, depending upon the phenotype of the parent.
	b.	the expression of a gene depends on the parental phenotype.
	c.	a gene is imprinted in the progeny, depending upon the age of the parent.
	d.	the expression of a gene in the progeny depends upon which parent the gene is inherited from.
	e.	only dominant traits are expressed

Fragile X syndrome:

	a.	is not inherited from the parents.
	b.	is due to genomic imprinting..
	c.	results in learning, attention, and hyperactivity disabilities in males.
	d.	results from a deletion of CGG sequences in the fragile X gene.
	e.	is characterized by a fragile site at the tip of the Y chromosome.

Colchicine is a drug that:

	a.	arrests cells in mitotic metaphase.
	b.	stimulates meiosis.
	c.	arrests cells in mitotic telophase.
	d.	prevents DNA replication.
	e.	prevents cells from entering prophase.

According to data from the ENCODE project, approximately 80% of the human genome is associated with biological function.

True

False

Huntington’s disease is caused by a:

	a.	rare recessive allele.
	b.	dominant X-linked allele.
	c.	monosomic condition.
	d.	deletion of part of chromosome 4.
	e.	nucleotide triplet repeat.

Match the genetic disease with the molecular defect.

	defect in the protein that regulates chloride transport across cell membranes
	absence of an enzyme to break down normal membrane lipid
	abnormality in a blood clotting protein
	hemoglobin molecules stick to each other
	defect in amino acid metabolism

a.	Phenylketonuria
b.	Sickle cell anemia
c.	Cystic fibrosis
d.	Tays Sach Disease
e.	Hemophilia A

Individuals who are ____ for sickle cell hemoglobin tend to be ____ resistant to falciparum malaria, but do not experience the effects of sickled red blood cells.

	a.	heterozygous; more
	b.	homozygous dominant; less
	c.	heterozygous; less
	d.	homozygous recessive; less
	e.	homozygous dominant; more

Nondisjunction during mitosis leads to:

	a.	death of the daughter cells.
	b.	nonviable sperm.
	c.	an individual with all abnormal cells.
	d.	an individual with a clone of abnormal cells.
	e.	normal daughter cells.

Aneuploidies describe:

	a.	a condition in which an extra chromosome is present or one is absent.
	b.	a defect that is always fatal in humans.
	c.	mutations that almost always have a beneficial effect on an individual.
	d.	a phenomenon that only occurs in plants.
	e.	an uncommon condition in humans.

Nondisjunction of the XY pair during the first meiotic division can produce sperm with 2 X chromosomes and 2 Y chromosomes.
_________________

True

False

In individuals with cystic fibrosis:

	a.	the mucus enhances the action of the cilia that line the bronchi.
	b.	the mucus prevents the growth of dangerous bacteria in the respiratory system.
	c.	the mucus in the respiratory system is thinner than in unaffected individuals.
	d.	abnormal mucous secretions occur throughout the body systems.
	e.	abnormal mucous secretions inhibit infections by bacteria.

A karyotype reveals that an individual is XYY. Based on your knowledge of human genetics, you correctly conclude that this individual has ____, and is a phenotypically _____.

	a.	Turner syndrome; fertile female
	b.	Turner syndrome; sterile female
	c.	XXY karyotype; fertile male
	d.	Klinefelter syndrome; fertile male
	e.	Klinefelter syndrome; sterile male

Down syndrome is an example of a ____ condition.

	a.	trisomic
	b.	polyploid
	c.	disomic
	d.	transgenic
	e.	monosomic

An advantage of chorionic villus sampling (compared with amniocentesis) is that:

	a.	chorionic villus sampling can be performed much earlier than amniocentesis.
	b.	chorionic villus sampling is much less invasive than amniocentesis.
	c.	chorionic villus sampling is much less expensive than is amniocentesis.
	d.	chorionic villus sampling detects a much wider range of genetic defects than does amniocentesis.
	e.	chorionic villus sampling is much easier to perform than amniocentesis.

Autosomal monosomy is not seen in live births because:

	a.	its effects are so small as to be overlooked.
	b.	its effects do not set in until adulthood.
	c.	its effects are so lethal as to cause spontaneous abortion early in pregnancy.
	d.	it only occurs in sex chromosomes and therefore does affect nonreproductive function.
	e.	the births lead to the establishment of a clone of abnormal cells

Persons having an XO karyotype are sterile females. They have ____ syndrome.

	a.	Down (trisomy form)
	b.	Klinefelter
	c.	Phenylketonuria
	d.	Down (translocation form)
	e.	Turner

Gene targeting has been used in mice to produce strains that were either homozygous or heterozygous for ____.

	a.	PKU
	b.	cystic fibrosis
	c.	Huntington’s disease
	d.	sickle cell anemia
	e.	Tays Sachs Disease

Cri du chat syndrome arises from:

	a.	a duplication of part of chromosome 15.
	b.	a 14/21 reciprocal translocation.
	c.	nondisjunction.
	d.	deletion of part of chromosome 5.
	e.	trisomy for chromosome 5.

Preimplantation genetic diagnosis is done:

	a.	in the womb, before birth.
	b.	with the help of ultrasound.
	c.	after a woman is pregnant, but before the embryo implants.
	d.	before fertilization on the sperm and the egg.
	e.	on cells of an in vitro fertilized embryo.

Breeding a yellow dog with a brown dog produced puppies with both yellow and brown hairs intermixed. This is an example of:

	a.	codominance.
	b.	variegation.
	c.	a polygenic trait.
	d.	epistasis.
	e.	incomplete dominance.

____ refers to multiple independent pairs of genes having similar and additive effects on the same characteristic.

	a.	Complete dominance
	b.	Codominance
	c.	Epistasis
	d.	Polygenic inheritance
	e.	Additive dominance

A gene that affects, prevents, or masks the expression of a gene at another locus is a(n) ____ gene.

	a.	recessive
	b.	dominant
	c.	epistatic
	d.	codominant
	e.	pleiotropic

All calico cats are female because:

	a.	two recessive X-linked genes are required for the calico phenotype.
	b.	one X chromosome and one Y chromosome are needed for the expression of the calico phenotype.
	c.	the calico phenotype is a Y-linked trait.
	d.	Y-linked genes prevent the expression of the calico phenotype.
	e.	the calico phenotype is caused by random X chromosome inactivation.

A diploid individual has a maximum of ____ different alleles for a particular locus.

	a.	one
	b.	two
	c.	three
	d.	four
	e.	more than four

A ____ is best used to demonstrate the linkage of two genes.

	a.	monohybrid test cross
	b.	two-point test cross
	c.	dihybrid cross
	d.	monohybrid cross
	e.	two-allele test cross

If a couple is planning on having two children, what is the probability that both will be male?

	a.	0
	b.	1/4
	c.	1/2
	d.	3/4
	e.	1

In a two-point test cross, 36 of the offspring were recombinant types. The remaining 64 offspring were parental types. How many map units separate the two loci?

	a.	28
	b.	36
	c.	64
	d.	78
	e.	100

A brown-eyed couple already has a child with blue eyes. What is the probability that their next child will have blue eyes, assuming that the brown eye allele is dominant and the blue eye allele is recessive?

	a.	0
	b.	1/4
	c.	1/2
	d.	3/4
	e.	1

The offspring of two heterozygous gray-bodied, normal-winged flies should be 50% gray-bodied/normal wings (BbRr) and 50% black-bodied/vestigial wings (bbrr) because these alleles are linked. Suppose a small number, say 15%, of the offspring are instead black-bodied with normal wings. This is most likely the result of:

	a.	mutation.
	b.	an error in meiosis.
	c.	incomplete dominance.
	d.	codominance.
	e.	crossing-over.

In rabbits, coat color is governed by four alleles: C for dark gray, C^ch for chinchilla, C^h for himalayan, and c for white. Each individual rabbit inherits a combined total of _____ coat color allele(s) from its parents.

	a.	four
	b.	two
	c.	zero
	d.	one
	e.	three

A lizard with a striped tail and a normal head is crossed with one having a normal tail and a spotted head. All of the F₁ progeny are normal (no stripes or spots). What progeny would be expected to be produced by mating the F₁ progeny with each other, if the genes conferring stripes and spots were on different chromosomes?

	a.	equal numbers of normal, striped, spotted and striped, and spotted
	b.	9 normal : 3 striped : 3 spotted : 1 striped and spotted
	c.	9 striped and spotted : 3 spotted : 3 striped : 1 normal
	d.	3 striped : 1 spotted
	e.	9 striped : 3 spotted : 1 striped or spotted

A pear plant with the genotype Aa can produce gametes containing:

	a.	either A or Aa.
	b.	only the dominant A.
	c.	only the recessive a.
	d.	either A or a.
	e.	either AA, Aa, or aa.

A heterozygous fruit fly with normal wings and a gray body (VvBb) is crossed with homozygous flies with vestigial wings and black bodies (vvbb). If there are 800 F₁ progeny, the expected phenotypes would be:

	a.	200 normal gray, 200 normal black, 200 vestigial gray, and 200 vestigial black
	b.	450 normal gray, 150 normal black, 150 vestigial gray, and 50 vestigial black
	c.	400 normal gray and 400 vestigial black
	d.	800 vestigial black
	e.	800 normal gray

A heterozygous fruit fly with normal wings and a gray body (VvBb) is crossed with homozygous flies with vestigial wings and black bodies (vvbb). Out of 800 total F₁ progeny, 296 are normal gray, 328 are vestigial black, 99 are normal black, and 77 are vestigial gray. What is the best explanation for this result?

	a.	The loci for wing length and body color are on sex chromosomes.
	b.	The loci for wing length and body color are on the same chromosome.
	c.	Mendel’s principle of independent assortment accounts for this.
	d.	Mendel’s principle of segregation accounts for this.
	e.	The loci for wing length and body color are on different chromosomes.

A couple has already had three girls with cystic fibrosis, and are hoping to have a normal child for their fourth. What are the chances that the fourth child will be a normal male?

	a.	1/8
	b.	0
	c.	1/2
	d.	1/4
	e.	3/8

Mating a true-breeding pink rose plant with a true-breeding pink rose plant will produce:

	a.	plants with pink, red, and white roses.
	b.	plants with only pink roses.
	c.	plants with red or white roses in a 3:1 ratio.
	d.	plants with white or red roses in a 3:1 ratio.
	e.	plants with only red roses.

In peas, Mendel found that tall plants and yellow peas are dominant. The phenotype for a pea plant with the genotype TTyy would be:

	a.	intermediate height with greenish-yellow peas.
	b.	tall with green peas.
	c.	tall with yellow peas.
	d.	short with yellow peas.
	e.	short with green peas

Color-blindness is more common in males than in females because:

	a.	females need to inherit only one copy of the recessive color blindness allele to express the trait.
	b.	males only need to inherit the recessive maternal color blindness allele to be color blind.
	c.	color-blindness is an autosomal trait.
	d.	all females are hemizygous for the color blindness trait.
	e.	males can only inherit paternal color blindness alleles.

Mendel verified true-breeding pea plants for certain traits before undertaking his experiments. The term “true-breeding” refers to:

	a.	organisms that are homozygous for all possible traits.
	b.	organisms that will produce identical copies of themselves upon reproduction.
	c.	organisms that have a high rate of reproduction.
	d.	genetically pure lines.
	e.	organisms that are heterozygous for a given trait.

____ are alternative forms of a gene that govern the same feature, such as eye color, and occupy corresponding positions on homologous chromosomes.

	a.	Alleles
	b.	Loci
	c.	Homozygotes
	d.	Coupled traits
	e.	Heterozygotes

The physical location of a particular gene on a chromosome is called:

	a.	an allele.
	b.	its locus.
	c.	a trait.
	d.	a chromatid.
	e.	its genotype.

In genetics, map units express the distance between:

	a.	alleles.
	b.	two loci on a chromosome.
	c.	polar bodies.
	d.	chromosomes during metaphase.
	e.	homologous chromosomes.

In rabbits, coat color is governed by four alleles: C for dark gray, C^ch for chinchilla, C^h for himalayan, and c for white. This is an example of:

	a.	X-linked genes.
	b.	epistasis.
	c.	codominance.
	d.	multiple alleles.
	e.	incomplete dominance.

A lizard with a striped tail and a normal head crossed with one having a normal tail and a spotted head produce all normal (no stripes or spots) F₁progeny. What progeny would be expected to be produced by mating either of the parental lizards with another that had a striped tail and spotted head, if the genes conferring stripes and spots were close together on the same chromosome?

	a.	3 striped : 1 spotted
	b.	9 normal : 3 striped : 3 spotted : 1 striped and spotted
	c.	mostly progeny that are striped or spotted
	d.	mostly progeny that are normal or striped and spotted
	e.	equal numbers of normal, striped, spotted and striped, and spotted

An organism with the genotype of AaXx can produce gametes containing ____ if the two genes are unlinked.

	a.	either Aa or Xx
	b.	either AX, Ax, aX, ax
	c.	AaXx only
	d.	AX or ax
	e.	A,a,X,x

In humans, assume that the allele for brown eyes is dominant and the allele for blue eyes is recessive. If two brown-eyed individuals have a child with blue eyes, that means:

	a.	both parents are homozygous for brown eyes.
	b.	both parents are heterozygous for eye color.
	c.	there is a 1/4 chance that their second child will have brown eyes.
	d.	there is a 1/2 chance that their second child will have blue eyes.
	e.	there is a 3/4 chance that their second child will have blue eyes

A heterozygous fruit fly with normal wings and a gray body (VvBb) is crossed with homozygous flies with vestigial wings and black bodies (vvbb). This type of cross is known as a:

	a.	dihybrid cross
	b.	polytropic cross.
	c.	monohybrid cross.
	d.	chromosomal cross.
	e.	true breeding cross.

A cross of two medium height hybrid plants produces offspring that are dwarf, medium, and tall in a ratio of 1:2:1. This is an example of:

	a.	a polygenic trait.
	b.	incomplete dominance.
	c.	hybrid vigor.
	d.	variegation.
	e.	epistasis.

The genotype for a pea plant that is homozygous recessive for both height and pea color would be:

	a.	YY.
	b.	tt.
	c.	TTYY.
	d.	TtYy.
	e.	ttyy.

A particular gene that controls seed coat color in peas also determines the susceptibility of these peas to a particular disease. This situation is referred to as:

	a.	incomplete dominance.
	b.	pleiotropy.
	c.	variegation.
	d.	polygenic inheritance.
	e.	codominance

If a couple is planning on having three children, what is the probability that only one will be male?

	a.	0
	b.	1/4
	c.	3/8
	d.	1/2
	e.	3/4

A female black cat mated with an albino male and gave birth to 6 black kittens. When the albino male was mated with a different female black cat, 3 black cats and 2 albino cats were produced. How can you explain this genetic situation? Write genotypes for all three parental cats and offspring.

Linked genes are located on ____ chromosomes and do not follow the principle of ____.

	a.	the same; independent assortment
	b.	sex chromosomes; segregation
	c.	different; independent assortment.
	d.	the same; segregation
	e.	different; segregation

A brown-eyed couple heterozygous for eye color are planning on having two children. What is the probability that both children will have blue eyes, assuming brown eyes is dominant and blue eyes is recessive?

	a.	0
	b.	1/32
	c.	1/16
	d.	1/4
	e.	1/2

Mating an individual expressing a dominant phenotype, but whose genotype is unknown, with an individual expressing the corresponding recessive phenotype is an example of a(n):

	a.	F₂ cross.
	b.	heterozygous cross.
	c.	F₁ cross.
	d.	parental cross.
	e.	test cross.

If an allele is dominant, then:

	a.	its phenotype is more beneficial than the recessive phenotype.
	b.	its phenotype is always expressed in all generations.
	c.	one allele can mask the expression of a recessive allele in a hybrid.
	d.	its phenotype is only expressed in heterozygous individuals.
	e.	its phenotype is expressed only in homozygous individuals..

The probability that two genes will be separated by crossing-over is related to:

	a.	how far the genes are from the kinetochore.
	b.	whether the two genes are located on a sex chromosome.
	c.	the phenotype that they control.
	d.	the distance between the two genes on the chromosome.
	e.	how far the two genes are from the centromere.

Mendel’s principle of segregation states that:

	a.	alleles from one parent mask the expression of alleles from the other parent.
	b.	true-breeding parents produce offspring of the same phenotype.
	c.	dominant and recessive alleles segregate during meiosis.
	d.	alleles separate from each other before forming gametes.
	e.	hybrids will express a phenotype intermediate between the two parental phenotypes.

A Barr body in a mammalian female cell represents a(n):

	a.	inactivated X chromosome.
	b.	inactivated Y chromosome.
	c.	inactivated oocyte.
	d.	polar body.
	e.	degenerate nucleus.

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