biology

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155 terms

Red blood cells have 6 different genotypes. These genotypes result in how many different phenotypes?

4

A man who is a silent carrier of the FMO3 "fish odor syndrome" has children by a woman who is "normal." Which of the following would best explain how a child born from these parents could have fish odor syndrome?

The mother is also a silent carrier of the defective FMO3 allele.

What was the MOST important scientific advance gained from Gregor Mendel's experiments with pea plants?

We learned that many traits are inherited in discrete units, and are not the result of blending.

If you crossed a snapdragon that had the CWCW genotype at the flower color gene with a snapdragon that had the CRCR genotype:

all of the offspring would have the CWCR genotype.

Red blood cells have how many different possible phenotypes?

4

Which term refers to the genetic control of continuously varying traits such as height?

polygenic

At locus A, the individual bearing these two homologous chromosomes is:

homozygous for the recessive allele.

The difference between incomplete dominance and codominance is:

...that in incomplete dominance, the offspring do not exhibit the traits of either parent, while in codominance, the offspring exhibit the traits of both parents.

When crossing-over occurs, _______________ genes usually stay together.

...linked

Peas (Pisum sativum) were well suited for Mendel's breeding experiments for all of the following reasons except:

D) peas have a particularly long generation time.

If two individuals who are heterozygous for the sickle-cell disease mate, their offspring:

C) will have a one-quarter chance of being a sickle-cell free homozygote.

Phenotypes are generally a product of:

the genotype in combination with the environment.

If you have A antigens, which antibodies will you produce?

both b) and c) are correct.

An individual's blood-type alleles carry instructions that direct construction of a specfic set of chemicals which protrude from every red blood cell. These chemicals are called antigens.

If you have A antigens, which antibodies will you produce?

B

Red blood cells have how many different possible genotypes?

6

Which of the following statements about Gregor Mendel is NOT correct?

His initial research was inspired by his desire to demonstrate that a tiny, pre-made human existed in each sperm cell.

How many human traits are controlled by a single gene?

over 9,000

The test-cross:

makes it possible to determine the genotype of an individual of unknown genotype who exhibits the dominant version of a trait.

We say that genes are linked when:

they are located near each other on a single chromosome

"Fish odor syndrome" is caused by:

the lack in an individual of alleles for the enzyme FMO3, which breaks down chemicals that cause a rotting fish odor.

Mendel's Law of Segregation has its physical basis in which of the following phases of the cell cycle?

the separation of homologous chromosome pairs in anaphase I of meiosis

On human chromosome 11 there is a gene called DRD4. This gene carries the instructions for building a protein that is receptor for the brain chemical dopamine. There are two different alleles, C and T, and it appears that having one or two copies of the T allele leads to reduced transcription of the dopamine receptor gene, while having the CC genotype is associated with greater gene activity.

What would you expect to be true of a person with the CC genotype?

they would be more likely to seek out novel experiences

The figure above provides an example of:

incomplete dominance.

Most genes come in alternative forms called:

alleles

In genetics, the separation of alleles or homologous chromosomes during meiosis so that the haploid daughter cells have one allele or the other but never both is also referred to as:

Both a) and b) are correct.

Phenylketonuria (PKU) is a disease characterized by the buildup of phenylalanine. The enzyme phenylalanine hydroxylase, which catalyzes the conversion of _________ to __________, is mutated and non-functional.

B) phenylalanine; tyrosine

Which of the following statements is true regarding pedigree analysis?

Darkened shapes always represent individuals with the trait being traced.

Phenylketonuria is a genetic disorder that:

causes the inability to convert phenylalanine to tyrosine

A particular trait is analyzed using a pedigree diagram. More males than females appear to be affected. This trait is probably:

sex-linked recessive.

The sickle-cell allele is considered to be pleiotropic because:

it has at least 2 effects: disrupting oxygen delivery and protecting against malaria

A situation in which the heterozygote offspring of two homozygotes show an phenotype intermediate between those of the parents is called:

incomplete dominance.

How can two pea plants that have different genotypes for seed color be identical in phenotype?

One of the two plants could be homozygous for the dominant allele while the other could be heterozygous.

In ABO blood group inheritance, what is the relationship between the alleles A and B (sometimes written as IA and IB)?

all of the offspring would have the CWCR genotype.

The ABO blood type system in humans is an example of:

multiple alleles and codominance

Tay-Sachs, which is a recessive lethal disease, results only when individuals possess two copies of the disease-causing allele. Which of the following statements is true about this disease?

A.
Heterozygous individuals may pass on their copy of the disease-causing allele to offspring.

The fact that freckles tend to be inherited with red hair is counter to which of Mendel's assertions?

...

If two individuals who are heterozygous for the sickle-cell disease mate, their offspring:

C) will have a one-quarter chance of being a sickle-cell free homozygote.

If a true-breeding blue-flowered plant was crossed with a true-breeding white-flowered plant, what phenotypic ratio would we observe in the progeny resulting from this cross? Assume the white-flowered trait is completely dominant.

100% white

Most, if not all, genes are:

pleiotropic

If you crossed a snapdragon that had the CWCW genotype at the flower color gene with a snapdragon that had the CRCR genotype:

All of the above are correct.

Genes that are _____________ do not assort independently, but they may recombine by crossing over.

linked

If two individuals who are heterozygous for the sickle-cell disease mate, their offspring:

both b) and c) are correct.

Which of the following did Gregor Mendel never see?

a gene

In humans, X-linked traits:

occur on the X chromosome

The SRY gene:

causes fetal gonads to develop as testes shortly after fertilization.

How many unique haploid gametic genotypes could be produced through independent assortment by an organism with the diploid genotype AABbCCDdEe?

8

In snapdragons, there is an allele for flower color, CW, that produces no pigment, and an allele for flower color, CR, that produces red pigment. A plant with the CWCR genotype will produce:

flowers of the same color as a plant with the CRCW genotype.

In pea plants, the allele for purple flower color is dominant to the allele for white flower color. If you were to perform a test-cross to determine the genotype of a purple-flowered plant, what would you expect the phenotypic ratio of purple-flowered to white-flowered progeny to be if the plant is homozygous? And what would you expect if the plant is heterozygous?

If the purple-flowered plant is homozygous, than the progeny would all have purple flowers; if the purple-flowered plant is heterozygous, then the progeny would have purple to white flowers in a 1:1 ratio.

Is it possible for a woman to have a X-linked recessive trait? If it is, how can this occur?

both b and c

An individual's blood-type alleles carry instructions that direct construction of a specfic set of chemicals which protrude from every red blood cell. These chemicals are called:

antingens

Autosomal dominant traits:

a) and b) are both correct.

Phenylketonuria is a good example of the environmental effects on phenotype because:

.its beneficial effects can be increased by limiting the amount of phenylalanine in the diet.
..

Four traits that Mendel studied extensively in pea plants were flower position, seed color, stem length, and pod shape. For flower position, the axial (A) allele is dominant over terminal (a); for seed color, the yellow allele (Y) is dominant over green (y); for stem length, the tall (T) allele is dominant over dwarf (t); and for pod shape, the inflated (I) allele is dominant over constricted (i). Imagine a tetrahybrid cross between two AaYyTtIi plants. What is the probability of observing an individual with the AaYYttIi genotype in the next generation?

...1/16

A true-breeding red rose is repeatedly mated with a true-breeding white rose, and all of their offspring are red. If two of these red offspring are mated, what percentage of their offspring will be red?

75%

If an individual that is homozygous for normal, circular red blood cells mates with an individual that is homozygous for sickle-shaped red blood cells, their offspring:

will have both circular and sickled red blood cells in their circulatory systems.

In certain plants, red flowers are dominant to white flowers. If a heterozygous plant is crossed with a homozygous red-flowered plant, what is the probability that the offspring will be white-flowered?

0%

Prior to Mendel:

humans observed and manipulated heredity, but did not understand how it worked.

Gregor Mendel bred two pea plants, one with purple flowers and one with white flowers and found that the next generation all had purple flowers. When he bred all of the plants in the generation with purple flowers, he found that the next generation had 3/4 purple flowers and 1/4 white flowers. What are the genotypes of the purple flowers of the last generation?

1 PP : 2 Pp

Which of the following is NOT a continuously varying trait?

widow's peak

The chance of two separate events occurring together is equal to the product of their separate chances. Two people who are carriers of the recessive Tay-Sachs gene decide to have children. What are the chances this couple will give birth to three children with Tay-Sachs?

1/64 or 1.56%

For the genetic cross Aa × Aa, 3:1 is the:

phenotypic ratio for the offspring if inheritance was by complete dominance.

Mary, who has type O blood, is expecting a child with her husband, who has type B blood. Mary's husband's father has type A blood. What is the probability that the child will have type O blood?

50%

Traits that are determined by a single gene:

are common in humans.

The figure shown here is from a "meta study" of all the published findings on the relationship between the CC genotype (linked to increased novelty-seeking behavior) and scores on novelty-seeking measures.

From the graph, how many studies were included in the meta study?

11

A man with kinky hair has children by a woman with non-kinky hair. They have five children, three of whom have kinky hair. Based on this information alone, what inheritance pattern is seen with the kinky hair trait?

single- gene trait

A man with the autosomal recessive disorder phenylketonuria (PKU) and a woman without PKU have a son named Peter, who does not have PKU. Peter is curious about whether his mother is a carrier for PKU. Which of the following facts would allow him to know?

Peter's maternal grandfather has PKU.

Assuming that a particular disorder is caused by an allele of a single gene, what feature of a pedigree would allow one to conclude that the disorder was caused by a dominant allele?

Two affected parents have an unaffected child.

A rare, X-linked dominant condition in humans, congenital generalized hypertrichosis, is marked by excessive hair growth all over a person's body. Which of the following statements about this condition is INCORRECT?

The son of a women with this disorder has a 100% chance of having this condition.

In peas, tall plants are dominant to short plants. A heterozygous plant is crossed with a homozygous recessive plant. What fraction of the offspring would you expect to have the short phenotype?

...

Assuming that a particular disorder is caused by an allele of a single gene, what feature of a pedigree would allow one to conclude that the disorder was caused by a dominant allele?

Two affected parents have an unaffected child.

Is it possible for a woman to have a X-linked recessive trait; if it is, how can this occur?

Yes, a woman can have an X-linked recessive trait if her father has the trait and her mother is either homozygous or heterozygous for the trait.

In peas, tall plants are dominant to short plants. A heterozygous plant is crossed with a homozygous recessive plant. What fraction of the offspring would you expect to have the short phenotype?

1/2

Which of the following results would mean that a test-cross investigation was complete, given that a pigmented alligator (M_) is crossed with an albino alligator (mm)?

...getting a single albino offspring

Recent research has identified two genes that help determine height in humans. Individuals with the "tall" allele for both genes are taller than those with the tall allele for only one. Individuals with one tall allele, in turn, are taller than people who do not have the tall allele for either gene. This is known as:

...

Mendel's Law of Segregation has its physical basis in which of the following phases of the cell cycle?

the separation of homologous chromosome pairs in anaphase I of meiosis

Some genes, such as the human ABO blood groups, have more than two alleles. For these genes:

individuals can only possess two alleles.

The MOST IMPORTANT reason that Mendel's law of independent assortment is NOT universally true is that:

B) genes are carried on chromosomes.

How many unique haploid gametic genotypes could be produced through independent assortment by an organism with the diploid genotype AABbCCDdEe?

...8

A man with kinky hair has children by a woman with non-kinky hair. They have five children, three of whom have kinky hair. Based on this information alone, what inheritance pattern is seen with the kinky hair trait?

single-gene trait

Two fruit flies are crossed, resulting in offspring with a 3:1 phenotypic ratio for a particular trait. This suggests:

that the parents were both heterozygous for the gene associated with that trait.

People with "sickle-cell trait" are heterozygous for their hemoglobin genes. The parasite that causes the disease malaria infects normal blood cells but cannot infect sickled blood cells. Why would having sickle-cell trait increase the fitness of an individual over those who were homozygous normal or with sickle-cell disease, in areas where malaria is common?

Individuals with sickle cell trait enjoy some protection against malaria but don't have the reduced life span of those with sickle cell disease.

On human chromosome 11 there is a gene called DRD4. This gene carries the instructions for building a protein that is receptor for the brain chemical dopamine. There are two different alleles, C and T, and it appears that having one or two copies of the T allele leads to reduced transcription of the dopamine receptor gene, while having the CC genotype is associated with greater gene activity.

they would think carefully before making a decision

Which of the following did Mendel NOT understand?

Some genes are linked together.

Heart disease is thought to be a polygenic disorder in humans. Knowing this, what would you expect to see if you screened 100 people for heart disease?

Those with heart disease should show a continuous range of symptoms, from very mild to very intense.

Four traits that Mendel studied extensively in pea plants were flower position, seed color, stem length, and pod shape. For flower position, the axial (A) allele is dominant over terminal (a); for seed color, the yellow allele (Y) is dominant over green (y); for stem length, the tall (T) allele is dominant over dwarf (t); and for pod shape, the inflated (I) allele is dominant over constricted (i). If a testcross was performed with plant with the AAYyTtII genotype, what is the probability of observing an individual with the AayyTtIi genotype in the next generation?

1/4

Which term refers to the genetic control of continuously varying traits such as height?

polygenic

Linked genes:

...

For gene P/p, the individual bearing these two homologous chromosomes:

is homozygous for the dominant allele.

Individuals carrying two non-functioning alleles for the gene producing the enzyme that converts phenylalanine into tyrosine:

may or may not develop phenylketonuria, because the environment (diet, in this case) also plays a role in determining their phenotype.

Which of the following is a single-gene trait?

the widow's peak hairline

The figure shown here is from a "meta study" of all the published findings on the relationship between the CC genotype (linked to increased novelty-seeking behavior) and scores on novelty-seeking measures.

What do the light blue bars in the graph represent?

...the number of studies and relative CC-individual novelty-seeking scores for each one

Gray hair in voles (H) is dominant to brown hair (h). Short claws (C) are dominant to long claws (c). What is the probablity that the offspring of the cross HhCc × HHcc will have gray hair and long claws?

50%

If a true-breeding blue-flowered plant was crossed with a true-breeding white-flowered plant, what phenotypic ratio would we observe in the progeny resulting from this cross? Assume the white-flowered trait is completely dominant.

100% white

Phenylketonuria is a good example of the environmental effects on phenotype because:

its adverse effects can be avoided by limiting the amount of phenylalanine in the diet.

In mice, the allele for brown coat color is completely dominant to the allele for white coat color. Which of the following is true about a true-breeding brown mouse?

...

Sickle-cell anemia is a genetic disease caused by the presence of a faulty hemoglobin gene (HbS). The normal version of this gene is HbA. Which of the following is TRUE about HbS and HbA?

...

Mendel's law of independent assortment states that the alleles at one locus separate independently of those at other loci. This law does not apply:

to genes located close together on the same chromosome.

Which of the following statements about Gregor Mendel is NOT correct?

By focusing on easily categorized traits, he was able to definitively classify the results of genetic crosses.

(see full question) The information in the table shows the possible genotypes resulting from the mating of two heterozygotes AaDd.

The allele A codes for normal pigmentation, a for albinism, D for dimpled chin, and d for non-dimpled chin.

What fraction of offspring would be expected to be albino with a non-dimpled chin

1/16

How many unique haploid gametic genotypes could be produced through independent assortment by an organism with the diploid genotype AABbCCDdEe?

8

In mice, the allele for brown coat color is completely dominant to the allele for white coat color. Which of the following is true about a true-breeding brown mouse?

all of the Above is correct

Sickle-cell anemia is a genetic disease caused by the presence of a faulty hemoglobin gene (HbS). The normal version of this gene is HbA. Which of the following is TRUE about HbS and HbA?

They're both alleles for the same trait.

Which of the following is NOT true about Mendel's genetics experiments?

Mendel believed that a tiny, pre-formed pea plant was passed via pollen to a pea plant egg.

An individual's blood-type alleles carry instructions that direct construction of a specfic set of chemicals which protrude from every red blood cell. These chemicals are called:

antingens

If you crossed a snapdragon that had the CWCW genotype at the flower color gene with a snapdragon that had the CRCR genotype:

all of the offspring would have the CWCR genotype.

In peas, yellow seeds (Y) are dominant to green seeds (y). A homozygous dominant and a homozygous recessive plant are crossed and have two offspring. These two offspring are now crossed with each other. What are the chances that the second generation of offspring (the offspring of the first offspring) will have yellow seeds?

...75%

An allele:

ALL THE ABOVE

Red blood cells have how many different possible phenotypes?

4

In certain plants, red flowers are dominant to white flowers. If a heterozygous plant is crossed with a homozygous red-flowered plant, what is the probability that the offspring will be white-flowered?

0%

The impact of a single gene on more than one characteristic is called:

pleiotropy

Four traits that Mendel studied extensively in pea plants were flower position, seed color, stem length, and pod shape. For flower position, the axial (A) allele is dominant over terminal (a); for seed color, the yellow allele (Y) is dominant over green (y); for stem length, the tall (T) allele is dominant over dwarf (t); and for pod shape, the inflated (I) allele is dominant over constricted (i). Imagine a tetrahybrid cross between two AaYyTtIi plants. What is the probability of observing an individual with the AaYYttIi genotype in the next generation?

1/64

An allele:

All of the above.

Which disease or condition shows evidence of pleiotropy?

sickle-cell anemia

Looking at the information in the table above, if the A allele results in normal pigmentation and the a allele in albinism, what fraction of offspring would you expect to show albinism?

...

Red blood cells have 6 different genotypes. These genotypes result in how many different phenotypes?

4

Thousands (or even tens of thousands) of different traits make up an individual. For this reason:

in a species with 23 different chromosomes, some traits must be coded for by genes on the same chromosome.

In genetics, the separation of alleles or homologous chromosomes during meiosis so that the haploid daughter cells have one allele or the other but never both is also referred to as:

Both a) and b) are correct.

A male with an X-linked recessive disorder mates with a female that is a carrier for this same X-linked recessive disorder. Which of the following is the correct expected frequency of this disorder in their children?

...50% frequency in both the sons and the daughters

In pea plants, the allele for purple flower color is dominant to the allele for white flower color. If you were to perform a test-cross to determine the genotype of a purple-flowered plant, you would expect the percehtage of purple-flowered progeny to be _________ if the plant is homozygous and _____________ if the plant is heterozygous.

100%, 50%

A man who is colorblind marries and has children by a woman who has normal color vision. The woman's father had normal color vision but her mother was colorblind. Color blindness is an X-linked recessive disorder. What are the chances that a child born to this man and woman will be a colorblind girl?

...25%

Which of the following statements is NOT true?

Genes for different characteristics are always inherited independently of each other.

Without knowing the genetic basis, humans have selectively bred for:

both a) and c).

Autosomal recessive traits:

...

How is codominance different from incomplete dominance?

...

Heart disease is thought to be a polygenic disorder in humans. Knowing this, what would you expect to see if you screened 100 people for heart disease?

Those with heart disease should show a continuous range of symptoms, from very mild to very intense.

Virtually everyone with __________________ has a parent that exhibits the same trait.

a cleft chin

Prior to Mendel:

humans observed and manipulated heredity, but did not understand how it worked.

Autosomal recessive traits:

can skip generations.

Four traits that Mendel studied extensively in pea plants were flower position, seed color, stem length, and pod shape. For flower position, the axial (A) allele is dominant over terminal (a); for seed color, the yellow allele (Y) is dominant over green (y); for stem length, the tall (T) allele is dominant over dwarf (t); and for pod shape, the inflated (I) allele is dominant over constricted (i). If a testcross was performed with plant with the AAYyTtII genotype, what is the probability of observing an individual with the AayyTtIi genotype in the next generation?

1/4

Is it possible for a woman to have a X-linked recessive trait; if it is, how can this occur?

Yes, a woman can have an X-linked recessive trait if her father has the trait and her mother is either homozygous or heterozygous for the trait.

How is codominance different from incomplete dominance?

None of the above is true about codominance and incomplete dominance.

In the ABO blood type system in humans, there are _________ different alleles, ____________ different phenotypes, and ____________ different genotypes.

three; four; six

A white-flowered plant is crossed with a red-flowered plant, and all of the offspring have pink flowers. This could be an example of:

...Both b) and c) are correct.

If you crossed a snapdragon that had the CWCW genotype at the flower color gene with a snapdragon that had the CRCR genotype:

ALL OF THE ABIOVE IS CORRECT

Some genes, such as the human ABO blood groups, have more than two alleles. For these genes:

individuals can only possess two alleles.

People with "sickle-cell trait" are heterozygous for their hemoglobin genes. The parasite that causes the disease malaria infects normal blood cells but cannot infect sickled blood cells. Why would having sickle-cell trait increase the fitness of an individual over those who were homozygous normal or with sickle-cell disease, in areas where malaria is common?

Individuals with sickle cell trait enjoy some protection against malaria but don't have the reduced life span of those with sickle cell disease.

Is it possible for a woman to have a X-linked recessive trait; if it is, how can this occur?

Yes, a woman can have an X-linked recessive trait if her father has the trait and her mother is either homozygous or heterozygous for the trait.

Which of the following statements about dominant traits is correct?

...

Progeria is a genetic disorder that causes numerous symptoms that resemble premature aging in patients. Progeria is caused by a dominant allele, and it always results in fatality before sexual maturity. Which of the following statements must be true about progeria?

...Every case of progeria must be caused by a new mutation.

Pedram and Monica are both heterozygous for the widow's peak trait. Individuals who have two copies of the widow's peak allele exhibit a sharp, pointed hairline. What is the probability that the couple's first three children will all have widow's peaks?

...1/64

Which of the following is NOT a continuously varying trait?

...BLOOD TYPE

Gregor Mendel bred two pea plants, one with purple flowers and one with white flowers and found that the next generation all had purple flowers. When he bred all of the plants in the generation with purple flowers, he found that the next generation had 3/4 purple flowers and 1/4 white flowers. What are the genotypes of the purple flowers of the last generation?

1 PP : 2 Pp

Your father's mother was a heterozygous carrier of a X-linked trait. If you are a male, what are the chances of you inheriting this X-linked trait by direct descent from your paternal grandmother?

...0%

The ABO blood type system in humans is a system that contains ________ alleles that produce __________ different phenotypes.

C) three; four

The MOST IMPORTANT reason that Mendel's law of independent assortment is NOT universally true is that:

B) genes are carried on chromosomes.

All genetically normal humans have:

44 autosomes

Traits that are determined by a single gene:

are common in humans.

Microsatellites are short sequences of DNA that consist of several two- or three- nucleotide motifs repeated in tandem (for example, AATAATAAT or GAGAGAGAGAGA). Each allele consists of a different number of repeats. Microsatellites are typically not under selection, and they are inherited through Mendelian inheritance. Given this information, which of the following questions might you answer with the use of microsatellites?

whether two puppies were sired by the same father

The SRY gene, found on the Y chromosome, causes fetal gonads to develop as testes, as well as causing many other developmental changes. The SRY gene shows both:

sex-linkage and pleiotropy

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