Biology Exam 4

An individual with (naturally) curly hair and an individual with (naturally) straight hair mate; all of their offspring have (naturally) wavy hair. If an individual with wavy hair mates with an individual with straight hair, what is the probability that their child will have curly hair?

0%

What is the key to the recognition of incomplete dominance?

The phenotype of the heterozygote falls between the phenotypes of the homozygotes.

A dihybrid cross produces 30 recombinant offspring out of a total of 1,000 offspring. What is the recombination frequency of the two gene pairs?

3%

Mendel's laws are based on the behavior of chromosomes during ________.

metaphase I and anaphase I of meiosis

A couple has two female children. What is the probability that their next child will be male?

50%

An individual with the blood group genotype L^ML^N has the phenotype MN. What is the relationship between the L^M and L^N alleles?

codominance

Experience with dog breeding has taught geneticists that ________.

geographically isolated groups of dogs may be selected for quite different traits, resulting in a different dog breed

An individual with the genotype AaBb produces four different gametes in equal proportions. This is a demonstration of ________.

Mendel’s law of independent assortment

Marfan syndrome is the result of inheriting a single allele. Individuals with Marfan syndrome are tall and long-limbed, and have both cardiovascular and eye defects. Marfan syndrome is an example of ________.

pleiotropy

An individual who is heterozygous for cystic fibrosis ________.

is a carrier

Linked genes are usually ________.

located close together on a chromosome

Which cross will produce only heterozygous offspring?

AA × aa

Alleles are described as ________.

alternate versions of a gene

Red-green colorblindness is inherited as a sex-linked recessive trait. The gene is found on the X chromosome. Can a man with normal color vision father a daughter who is red-green colorblind?

No, he can't (unless there is a mutation).

Attached earlobes are recessive to free earlobes. What is the probability of having a child with attached earlobes when an individual with attached earlobes mates with an individual heterozygous for free earlobes?

50%

Hypophosphatemia (vitamin D–resistant rickets) is inherited as a sex-linked dominant trait. The relevant gene is found on the X chromosome. What is the expected outcome of a cross between a homozygous recessive woman and a man with hypophosphatemia?

All of their daughters and none of their sons exhibit hypophosphatemia.

Assume that having three nostrils is inherited as a sex-linked trait on the Y chromosome. A man with three nostrils has a daughter who has a son with a man who has only two nostrils. What is the probability that the three-nostril man's grandson has three nostrils?

0%

A BbCc × bbcc cross that produces offspring in a 5:5:1:1 phenotypic ratio is evidence of ________.

linked genes

An individual with (naturally) curly hair and an individual with (naturally) straight hair mate; all of their offspring have (naturally) wavy hair. What is the relationship between the alleles for hair texture?

incomplete dominance

The ________ is most commonly found in nature.

wild-type trait

What would you examine to determine whether a trait is sex linked?

pedigree

Achondroplasia is a form of dwarfism caused by a dominant allele. The homozygous dominant genotype causes death, so individuals who have this condition are all heterozygotes. If a person with achondroplasia mates with a person who does not have achondroplasia, what percentage of their children would be expected to have achondroplasia?

50%

In humans, free earlobes (E) are dominant to attached earlobes (e) and the presence of freckles (F) is dominant to the absence of freckles (f). If an individual heterozygous for both of these traits were to mate with an individual with attached earlobes and no freckles, what is the probability of having a child with attached earlobes and freckles?

25%

An individual with the genotype AaBb produces four different gametes in equal proportions. This is a demonstration of ________.

Mendel's law of independent assortment

Mendel crossed purebred purple-flowered plants with purebred white-flowered plants, and all of the resulting offspring produced purple flowers. The offspring are all ________, and the allele for purple flowers is ________.

heterozygotes; dominant

What is the key to the recognition of codominance?

The heterozygote expresses the phenotype of both homozygotes.

Which outcome could help you identify a trait whose expression is determined by the effects of two or more genes (polygenic inheritance)?

The trait varies along a continuum in the population.

Mendel's law of segregation indicates that

gametes have one allele copy for each gene.

In humans, free earlobes (E) are dominant to attached earlobes (e) and the presence of freckles (F) is dominant to the absence of freckles (f). If an individual heterozygous for both of these traits were to mate with an individual with attached earlobes and no freckles, what is the probability of having a child with attached earlobes and freckles?

25%

Many human traits, such as our performance on intelligence tests or our susceptibility to heart disease, are ________.

influenced by both genes and the environment

The best definition of a purebred plant is one that ________.

passes on the next generation only those traits identical to the parent

A mating between a purebred purple-flowered pea plant and a purebred white-flowered pea plant would produce a(n) ________.

hybrid

Which technique is used to collect fetal cells during pregnancy for genetic testing?

amniocentesis

Round seeds (R) are dominant to wrinkled seeds (r), and yellow seeds (Y) are dominant to green seeds (y). What is the expected phenotypic ratio of a cross between an RrYy and an rryyindividual?

1:1:1:1

Genes that violate Mendel's principle of independent assortment are ________.

linked

What is the specific location of a gene on a chromosome?

locus

An individual who is homozygous ________.

carries two copies of the same allele for a gene

To determine the phenotype of an individual who expresses a dominant trait, you would cross that individual with an individual who ________.

is homozygous recessive for that trait

A purebred plant that produces yellow seeds is crossed with a purebred plant that produces green seeds. The F₁ plants have yellow seeds. What is the expected phenotypic ratio of seed color of the offspring of an F₁ × F₁ cross?

3:1

In humans, the presence or absence of dimples is a trait controlled by a single gene. What is the genotype of an individual who is heterozygous for dimples?

Dd

A purebred plant that produces yellow seeds is crossed with a purebred plant that produces green seeds. The seeds of all of the offspring are yellow. Why?

The yellow allele is dominant to the green allele.

Which trait is polygenic in humans?

height

Inheritance of certain genes increases the risk of getting certain cancers; thus, it can be said that ________.

predisposition to these cancers is inherited

What can scientists achieve by injecting siRNAs into a cell via the process of RNA interference?

Scientists can prevent genes from being expressed.

In an operon, the ________ acts as an on/off switch.

operator

Repressors act by blocking the binding of ________ to the operator.

RNA polymerase

What is the function of a repressor protein?

To turn off transcription by binding to the operator.

Identify a difference between embryonic and adult stem cells from the following list.

Embryonic stem cells are undifferentiated; adult stem cells are partially differentiated.

Which is a possible result of a miRNA molecule binding to an mRNA molecule?

degradation of the mRNA

Reproductive cloning has many applications. Choose the exception.

creating stem cells to treat human diseases

Homeotic genes ________.

are evidence of the common ancestry of eukaryotic organisms

The process by which genotype becomes expressed as phenotype is ________.

gene expression

In a eukaryotic cell an abnormal protein is binding to the promoter for a gene. Which process will likely occur in this scenario?

The gene will be expressed normally.

Many proto-oncogenes regulate ________.

cell division

Which technique could tell you how gene expression differs between individuals with and without cystic fibrosis?

DNA microarray

Suppose a cDNA has the sequence CTTAGGA. What is the corresponding mRNA sequence?

GAAUCCU

More people die of ________ cancer than of any other cancer.

lung

If you were working for a pharmaceutical company trying to develop anticancer drugs, what biological process would be the best target to investigate?

mitosis

Homeotic genes are important for ________.

the development of an organism's body plan

While examining a human cell that functions normally, you determine that it has 45 functional chromosomes and one chromosome that is almost completely inactive. You immediately decide that it is very likely that this cell ________.

came from a normal human female

When referring to cell division, oncogenes are most like ________ while tumor suppressor genes are most like ________.

the gas pedal on a car; the brakes on a car

Bacterial RNA polymerase binds to the ________.

promoter

How can mature plants be cloned to produce genetically identical copies?

Mature plant cells can develop into all the specialized cells of an adult plant.

What is the benefit of using avatars in cancer treatments?

Avatars allow clinicians to identify more effective drugs to use.

Non-coding DNA sequences are referred to as ________.

introns

What would enable a single RNA transcript to be translated into different polypeptides?

The RNA transcript can be spliced more than one way.

What name is given to a gene that causes cancer?

oncogene

Which of these lifestyle choices will increase cancer risk?

changing to a diet low in plant fiber

________ is(are) responsible for more cancers than any other carcinogen.

tobacco

How are the cells in different body tissues able to perform different functions?

The cells exhibit different patterns of gene expression.

Which of these plays a role in the regulation of transcription in both prokaryotic and eukaryotic cells?

attachment of RNA polymerase to the promoter

About one out of how many women will develop breast cancer?

8

Cells communicate with one another via ________.

signal transduction pathways

Which is most likely to cause the development of a six-legged frog?

mutation of homeotic genes

In bacteria, what name is given to a cluster of genes with related functions, along with their DNA control sequences?

operon

In a eukaryotic cell an abnormal protein is binding to the promoter for a gene. Which process will likely occur in this scenario?

Transcription factors will bind to enhancers.

In prokaryotes, the production of a single RNA transcript for a group of related genes is under the control of ________.

an operon

Which is a type of post-transcriptional regulation of gene expression?

breakdown of proteins

What would you assume if you found RNA transcripts of lactose-utilizing genes within E. coli?

Lactose is present in the cell.

Reproductive cloning has many applications. Choose the exception.

Reproductive cloning has many applications. Choose the exception.

Tumor cells can change over time in a variety of ways. The following options are all ways that tumors change over time except for one. Choose the exception.

Tumor cells grow uncontrollably.

A researcher is attempting to use RNAi to investigate the function of citrate synthase, an enzyme that is involved in the Kreb's cycle. If the researcher injected siRNAs complementary to citrate synthase mRNA into cells, what is the most likely outcome that she would observe?

Less citrate synthase protein would be produced.

What type of protein binds to silencers to prevent gene expression from occurring?

repressors

The state of human gene therapy today is that ________.

there have been a small number of successes, including with the disease SCID

What is the best definition for recombinant DNA?

DNA that includes nucleotides from two different sources

Gel electrophoresis separates DNA fragments on the basis of differences in their ________.

length

What is the definition of a "transgenic organism?"

an organism containing a gene from another species

Transgenic animals are currently produced for many different reasons. Choose an example of a transgenic animal that currently does not exist.

chickens that have been modified to be able to lay eggs in very hot temperatures

In human gene therapy ________.

normal versions of human genes are transferred to patients who carry a mutated allele

To make restriction fragments, a DNA sample is treated with ________.

restriction enzymes

Of these steps, which one occurs earliest in the process of producing recombinant DNA?

Restriction enzymes are used to isolate the gene of interest and to cut the plasmid DNA.

STR analysis is a DNA profiling technique that makes use of the fact that different people have ________.

different numbers of repeats of short DNA sequences at certain sites in the genome

FGA is one of the STRs that are used to compare DNA between different people. Why is FGA useful for comparing DNA between different people?

FGA varies in the number of repeats between different people.

The human genome contains approximately ________ genes.

21,000

Approximately what percentage of the human genome consists of noncoding DNA?

98.5%

Genetically modifying human ________ may directly affect future generations.

eggs and sperm

Golden rice 2 is a genetically modified form of rice that was developed to treat what nutritional deficiency?

vitamin A

Which of these statements can be logically inferred from the amount of DNA shared by chimpanzees and humans?

Humans and chimpanzees share a relatively recent common ancestor.

What is the definition of a "transgenic organism?"

an organism containing a gene from another species

The process of making multiple copies of a gene by inserting it into a host genome and culturing the host is an example of ________.

gene cloning