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During transcription, at the point where the DNA strand being copied has an adenine, _______________ is added to the mRNA.

a uracil

Which of the following correctly describes the locations of transcription and translation within a eukaryotic cell?

DNA is transcribed in the nucleus, then the mRNA transcript is transported to the cytosol to be translated into protein.

In any DNA molecule, the number of guanine bases will:

always be equal to the number of cytosine bases.

The incidence of Tay-Sachs disease has been reduced by 75% since the introduction of genetic screening in 1969. Which of the following is NOT an important component of this reduction in incidence of Tay-Sachs disease?

the fact that Tay-Sachs is caused by a dominant allele

If the probability of a point mutation in a species were 10-8 per base pair per generation and each gamete in that species contained 3 x 10-8 base pairs, how many new point mutations would you expect per gamete per generation?

3

From DNA to protein involves which series of events?

transcription, translation

The mechanism by which the information contained in DNA is coded into a complementary RNA copy is called:

transcription.

When a triplet of bases in the coding sequence of DNA is GCA, the corresponding codon for the mRNA that is transcribed from it is:

CGU.

The Russian-American biochemist Phoebus Levene was the first to determine that nucleotides may contain one of four different nitrogen-containing bases. Levene believed that the nitrogen-containing bases occurred in equal amounts in DNA. What is the actual proportion of these bases?

DNA contains equal amounts of adenine and thymine, and equal amounts of guanine and cytosine.

Bacteria use restriction enzymes to:

destroy foreign DNA.

Which of the following is a symptom of vitamin A deficiency?

blindness

Genotype is to phenotype as:

recipe is to cookie.

Transcription is like copying a recipe onto a notecard, EXCEPT:

the copy is made in code.

Approximately how many genes are estimated to exist in the human genome?

25,000

Which of the following statements about the metabolism of ethanol (which is present in alcoholic beverages) is INCORRECT?

All of the above are correct.

In humans, genes make up ______ of DNA.

less than 5%

In order for a person's DNA to be used for his or her identification, which of the following tools/techniques must also be used in the process?

All of the above tools/techniques must be used.

A "pseudogene" is best defined as:

a DNA sequence that arose from a duplication of a functional gene, but which itself is not expressed.

The human genome is composed of approximately how many base pairs?

3 billion

The double helix model of DNA suggested by Watson and Crick was exciting to the scientific community because:

it explained how genetic material could be duplicated by means of the complementary strands.

Gene therapy involves:

introducing non-defective genes into the cells of an individual with a genetic disorder.

The combination of DNA from two or more sources is called:

recombinant DNA.

The central dogma of molecular biology states that:

DNA is transcribed into RNA which is translated into protein.

After amplifying one gene of interest using PCR (polymerase chain reaction), you pour your DNA sample into a gel to ensure that the reaction worked. To your surprise, two bands are present on the gel instead of a single band. What is a likely explanation for this outcome?

Two alleles exist for the gene and they vary in size.

A person's unique DNA is carried within some of the cells and tissues of their body. These include all of the following EXCEPT:

All of the above contain a person's DNA.

The yeast genome is approximately 1/250 the size of the human genome and yet it contains approximately 1/5 the number of genes. Which of the following is the BEST explanation for this?

The yeast genome contains much less intergenic DNA and fewer introns.

Genetically modified weed-resistant canola plants were cultivated in Canada, making it possible for farmers to apply herbicides freely to kill the weeds but not the canola plants. What went wrong with this scenario?

The weed-resistant canola plants spread by seed to neighboring farms that weren't growing canola. The weed-resistant canola plants grew out of control, because traditional herbicides could not kill them.

Which of the following is a symptom of vitamin A deficiency?

blindness

The expression of a gene to form a polypeptide occurs in two major steps. What are these two steps in their correct chronological order?

transcription and then translation

Bt corn is a genetically engineered plant. What feature gives it value as a crop plant?

The plant produces a toxin designed to kill corn borers.

The mechanism by which the information contained in DNA is coded into a complementary RNA copy is called:

transcription.

The highest percentage of non-coding DNA is found in:

eukaryotes, with the exception of yeasts.

One of the four nucleotide bases in DNA is replaced by a different base in RNA. Which base is it, and what is it replaced by?

thymine, replaced by uracil

Recombinant human ____________________ is the chemical at the center of the "blood doping" scandals in professional cycling.

erythropoietin (EPO)

When the polymerase chain reaction (PCR) is used to amplify segments of DNA, the sample is first heated, then cooled, in cycles. How many cycles of heating and cooling would be necessary to produce four times the original quantity of DNA?

two

Transgenic bacteria are bacteria:

that have a sequence of DNA from another organism inserted into them.

You amplify the same gene from two different people using PCR (polymerase chain reaction). When you electrophorese the two samples on a gel, you see that two bands are present in the sample from Individual 1, while only one band is present in the sample from Individual 2. What is a likely explanation for this outcome?

Individual 1 is heterozygous, while Individual 2 is homozygous.

Which of the following molecules is NOT DIRECTLY involved in translation?

DNA

Diabetes is a chronic disease in which the body cannot produce ________________, a chemical that allows cells to take up and break down sugar from the blood.

insulin

One of the possible concerns about genetically modified foods is that they might kill organisms that we don't want to kill. Which of the following is an example of this phenomenon?

The pollen from plants containing insect-killing Bt genes can be blown onto other plants. Insects that we don't want to kill, such as monarch butterflies, may be killed by such pollen.

Measures of overall DNA similarity between chimpanzees and humans reveal that _____ of our base pairs are the same.

96%

Golden rice:

could help the 250,000 children each year who are at risk of blindness due to vitamin A deficiency.

A frameshift mutation:

results from an insertion or deletion in a DNA sequence.

Which of the following nucleotide bases are present in equal amounts in DNA?

Both a) and c) are correct.

In order for a eukaryotic cell to undergo reproduction and divide, certain steps must be successfully completed. Select from the choices below the one that is NOT one of these necessary steps.

There must be proper reshuffling of the genetic material in order to provide diversity within the gametes.

Down syndrome results from which of the following chromosomal abnormalities?

all or part of a third copy of chromosome 21

A karyotype:

can be used to diagnose Down syndrome in humans.

The only situation in which a person can survive without one of a pair of chromosomes is:

Turner Syndrome, X_, in which a female has only one sex chromosome.

In humans, the haploid number, n equals:

23.

The interphase stage in the eukaryotic cell cycle has the subgroups:

Gap 1, DNA synthesis, and Gap 2.

If a cell becomes arrested within the cell cycle because it is unable to replicate its DNA, which of the stages would you predict it would become arrested in?

Gap 1 phase

The majority of a eukaryotic cell's life is spent in an "in-between-division" stage referred to as:

interphase.

Cytokinesis:

refers to the division of a cell's cytoplasm.

Using a light microscope, it is easiest to see chromosomes:

during mitosis and meiosis because the condensed chromosomes are thicker and therefore more prominent.

A karyotype of one of your skin cells would reveal a total of 46 chromosomes. How many of these are maternally inherited autosomes?

22

Hermaphrodites are individuals with functioning male and female reproductive organs capable of producing both male and female gametes. Which of the following statements about hermaphrodites is INCORRECT?

An XXY human is a hermaphrodite.

_________ marks the break in the cell cycle between the end of mitosis and beginning of the synthesis stage.

Gap 1

A cell is said to have reached the metaphase stage of mitosis when:

the centromeres have arrived at the equatorial plate.

Naturally occurring chemicals in plants may be useful in inhibiting cancer. One of these chemicals that is found in grapes and peanuts is called:

resveratrol.

Which of the following are features that distinguish cancer cells from normal cells?

Both b) and d) are correct.

The purpose of mitosis is to enable existing cells:

to generate new, genetically identical cells.

Prokaryotic cells generally have a single circular chromosome attached to:

the cell membrane.

DNA replication occurs during the _____________ phase of the cell cycle.

DNA synthesis

In some species, sex is determined by environmental, rather than genetic, factors. This is true of:

turtles.

Which of the following human sex chromosome genotypes is not possible?

Y_

If a cell becomes arrested within the cell cycle because it is unable to replicate its DNA, which of the stages would you predict it would become arrested in?

Gap 1 phase

Which of the following is NOT a characteristic of Turner Syndrome?

XX genotype

In female gamete development in humans and other vertebrates, the net result of meiosis is the production of one large egg and three small cells with very little cytoplasm. These three small cells:

degrade almost immediately.

Somatic cells can include:

Both a) and b) are correct.

Sex cells having the ___________ number of chromosomes are called ____________.

haploid; gametes

Mitosis results in:

daughter cells with the same number and composition of chromosomes.

In most bacteria, the DNA is carried:

in a single circular chromosome.

In mitosis, telophase occurs when:

Both a) and b).

During meiosis, chromatin:

condenses, becoming more tightly coiled.

A cell is said to have reached the metaphase stage of mitosis when:

the centromeres have arrived at the equatorial plate.

A karyotype:

can be used to diagnose Down syndrome in humans.

The interphase stage in the eukaryotic cell cycle has the subgroups:

Gap 1, DNA synthesis, and Gap 2.

_________ marks the break in the cell cycle between the end of mitosis and beginning of the synthesis stage.

Gap 1

Trisomy 21 is a consequence of _______________________, the unequal distribution of chromosomes during meiosis.

nondisjunction

The eukaryotic cell cycle consists of four phases, in the following order:

mitosis, Gap 1, DNA synthesis, and Gap 2

Animal cells have "counters" that keep track of how many times a cell has divided. These counters are called:

telomeres.

Which of the following statements is NOT correct of human sex chromosomes?

All diploid cells have both an X and a Y chromosome.

Chemotherapy is one common treatment for cancer. Which of the following are aspects of chemotherapy?

All of the above are correct.

The rate at which mitosis occurs varies dramatically for different types of cells. The most rapid cell division occurs:

in the blood and the cells lining the various tissues of organs.

Trisomy 21 is a consequence of _______________________, the unequal distribution of chromosomes during meiosis.

nondisjunction

Prokaryotic cells generally have a single circular chromosome attached to:

the cell membrane.

The difference in sizes between male and female gametes results from two unequal divisions of __________________ in female gamete development.

cytoplasm

A diploid cell undergoes meiosis. What are the products of this division?

four haploid cells

The eukaryotic cell cycle consists of four phases, in the following order:

mitosis, Gap 1, DNA synthesis, and Gap 2

What are the two major methods of cellular division in eukaryotic cells?

meiosis and mitosis

In the ______________ process of DNA replication, each of the single strands becomes a double strand as an enzyme connects the appropriate complementary base to the exposed base.

rebuilding

Chromosomes on which recombination takes place:

Both a) and b) are correct.

Crossing over is the mixing of chromosomes which results in the recombination of genes on the same chromosome. Which of the following correctly describes the process of crossing over?

Two chromatids (one maternal and one paternal) break off at corresponding points on homologous chromosomes. The pieces of chromatid rejoin to the chromosome in each other's places.

Which of the following statements is NOT correct of human sex chromosomes?

All diploid cells have both an X and a Y chromosome.

Nondisjunction:

is the unequal division of the genetic material during cell division.

A karyotype of one of your skin cells would reveal a total of 46 chromosomes. How many of these are maternally inherited autosomes?

22

Whether it is eggs or sperm being produced through meiosis, under normal circumstances, each gamete ends up with:

exactly one copy of each chromosome.

The egg cells of a horse contain 32 chromosomes. How many chromosomes are in the horse's liver cells?

64

In DNA replication, when the DNA molecule separates into two strands:

Only a) and b) are correct.

Anaphase of mitosis occurs when:

the chromatids begin to separate from the metaphase plate.

The DNA in linear eukaryotic chromosomes is wrapped around proteins called _____________, which keep the DNA from getting tangled and enable an orderly, tight, and efficient packing of the DNA inside the cell.

histones

Some fertility clinics now promise that a couple can choose the sex of their baby. What technique might allow for this?

Both a) and d) are correct.

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