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Biology & Life Science
Q:
What is a point mutation?
A) a mutation that affects a single cell
B) a mutation in which one chromosome is lost
C) an error in DNA that is caused by malfunctioning of DNA ligase
D) a mutation found at a single base pair in the genome
E) a mutation that affects only one metabolic pathway
Q:
Melanoma is a cancer that is frequently associated with a mutation in what gene?
A) in the IT15 gene
B) in the DNA polymerase gene
C) in the BRAF gene
D) in the Huntington gene
Q:
Mutations that occur in somatic cells are:
A) responsible for the appearance of human diseases such as sickle-cell anemia.
B) never harmful.
C) passed on to successive generations when they are incorporated into gametes.
D) not passed on to future generations.
E) always harmful.
Q:
On average, if you examine 1 million human cells looking at a single gene, you'll find one cell with a mutation in that gene. If you were looking at a gene that could lead to cancer when mutated, how many mutated copies of that gene would you find in a person? (Assume a person contains 100 trillion [100,000,000,000,000] cells.)
A) 100,000,000
B) 1,000
C) 1,000,000
D) 10,000,000,000
E) 100
Q:
Cancer is a disease caused by mutations. Yet in most instances if one of your parents tragically died from cancer, this does not put you at greater risk than a person whose parents do not develop cancer. How can cancer be caused by mutations and yet not be heritable?
A) The mutations that cause cancer are special and cannot be passed on regardless of what type of cell they occur in.
B) Most cancers arise from mutations in germ-line cells.
C) Most cancers arise from mutations in somatic cells.
D) Cancer-causing mutations are repaired in offspring but not in parents.
Q:
The average mutation rate for DNA replication is 1 mutation for every 10 billion (10,000,000,000) nucleotides of DNA replicated. Yet DNA polymerase makes a mistake during replication at an average of 1 in 100,000 nucleotides. What does this say about DNA replication?
A) Most errors in DNA replication become mutations.
B) The base-pairing rules (A pairs with T and G pairs with C) prevent any mutations.
C) Cells are extraordinarily proficient at repairing errors made during DNA replication.
D) Cells recognize that a small fraction of mutations are beneficial to organisms and do not repair those.
Q:
The DNA of a cell is analyzed and found to contain 28 percent thymine. What percent of the DNA would by cytosine?
A) 22 percent
B) 28 percent
C) 50 percent
D) 25 percent
Q:
There are two alleles for each gene in a cell. If each gene encodes for a particular protein, what would make two alleles different from each other?
A) The sequence of bases in the DNA for each allele would be slightly different and would lead to the production of slightly different proteins.
B) The sequence of bases in the DNA would be different for each allele, but they would result in the production of identical proteins.
C) The sequence of bases in the DNA would be identical for each allele, but they would produce very different proteins.
D) The sequence of bases in the DNA would be identical for each allele, but one would produce a protein and the other would not.
Q:
A DNA molecule can be described as a twisted ladder. The ________ form the sides, and the ________ form the rungs.
A) base pairs; sugar-phosphate chains
B) sugars; phosphates
C) sugars; base pairs
D) sugar-phosphate chains; base pairs
Q:
A key part of DNA's function is to encode information. In considering how information-rich a particular molecule might be, a question is how many different sequences are possible in a particular length of the molecule. In the case of DNA the four different nucleotides can be arranged in any order. How many different sequences are possible for a DNA strand three nucleotides long?
A) 4
B) 32
C) 16
D) 64
E) 3
Q:
The three components of a DNA nucleotide are:
A) amino acids, phosphates, and deoxyribose.
B) bases, deoxyribose, and polymerases.
C) genes, sugars, and bases.
D) phosphates, sugars, and bases.
E) polymerases, ligases, and sugars.
Q:
In DNA, A, C, G, and T are abbreviations for the:
A) different types of bases on the nucleotides.
B) different types of sugars on the nucleotides.
C) types of genes found on DNA chromosomes.
D) different types of bonds that form between nucleotides.
E) different types of phosphates on the nucleotides.
Q:
What is the complementary sequence for a segment of DNA with the sequence ACGGCT?
A) TCGGCA
B) AGCCGT
C) TGCCGA
D) ACGGCT
E) GTAATC
Q:
If the sequence TCGTA was used as a template in DNA replication, what would be the sequence of bases on the newly synthesized strand?
A) ATGCT
B) CTACG
C) AGCAT
D) GCATC
E) TCGTA
Q:
The two strands of a double helix of DNA are linked by what kind of bond?
A) sugar-phosphate linkages
B) hydrogen bonds between bases
C) hydrogen bonds between sugars and phosphates
D) sugar-base linkages
E) base-phosphate linkages
Q:
What happens to the two original strands of a DNA molecule after the DNA has replicated?
A) After serving as replication templates, the two original strands are rejoined.
B) After serving as replication templates, the two original strands are destroyed.
C) Nucleotides from the original strands are randomly incorporated into the new strands.
D) Incomplete segments of the original strands end up in each newly synthesized strand.
E) Each original strand ends up paired with a newly synthesized strand.
Q:
A base pair is a unit of DNA that consists of:
A) one sugar bonded to one phosphate.
B) a single chromosome.
C) one nucleotide.
D) two nucleotides, one on each complementary strand of a DNA molecule.
E) two identical chromosomes.
Q:
The nucleotides in one strand of DNA are held together by:
A) bonds between the sugar of one nucleotide and the base of the next.
B) hydrogen bonds between phosphates.
C) bonds between the phosphate of one nucleotide and the base of the next.
D) hydrogen bonds between complementary bases.
E) links between the sugar of one nucleotide and the phosphate of the next.
Q:
How many different types of bases are used to encode all the genetic information in a molecule of DNA?
A) 2
B) 4
C) 20
D) 10
E) 5
Q:
What are the products of the replication of one DNA molecule?
A) four identical double-stranded DNA molecules
B) two strands joined into one double-stranded DNA molecule
C) two identical double-stranded DNA molecules
D) a set of four sister chromatids
E) a pair of homologous chromosomes
Q:
What is meant by saying one strand of DNA is the template for the synthesis of another strand?
A) A strand of DNA is taken apart to supply nucleotides for synthesis of a new strand.
B) One strand of DNA acts as a wedge to separate other strands before replication.
C) The template specifies the order of bases of the strand being made.
D) The new strand will have exactly the same base sequence as the template strand.
E) A strand of DNA is the enzyme that connects nucleotides in replication.
Q:
Which of the following statements about the two strands of a DNA molecule is true?
A) An A base on one strand always pairs with a G base on the other strand.
B) The strands are a pair of sister chromatids.
C) The strands are connected to each other by sugar-phosphate bonds.
D) A T base on one strand always pairs with an A base on the other strand.
E) The strands have identical base sequences.
Q:
What is the function of DNA polymerase?
A) synthesizing nucleotides from free sugars, phosphates, and bases
B) halting DNA replication if a cell becomes cancerous
C) breaking sugar-phosphate bonds to release free nucleotides for DNA synthesis
D) introducing mutations into DNA for evolutionary adaptation
E) joining together nucleotides as they are base-paired during DNA replication
Q:
Imagine that the DNA replication error rate for a strain of bacterium that has a defective repair mechanism is 1 in 10 million. If the cell's genome is 5 million nucleotide pairs, how often will the genome sustain a mutation in this strain, keeping in mind that both strands of a DNA molecule are replicated at once?
A) once every five cell divisions
B) once per cell division
C) twice per cell division
D) four times per cell division
E) once every ten cell divisions
Q:
What is one way that incorrect nucleotides are removed from a newly synthesized molecule of DNA?
A) Crossing over replaces regions with DNA errors with new segments of DNA.
B) DNA ligases both remove and replace incorrectly positioned nucleotides.
C) Any DNA strand with an error is destroyed, and an entire new strand is synthesized.
D) DNA polymerases remove incorrect nucleotides and replace them with correct ones.
E) DNA ligases remove incorrect nucleotides for replacement by DNA polymerases.
Q:
What is the relationship between DNA and proteins?
A) Genes are made of proteins that encode the base sequence of DNA.
B) DNA stores the information needed to make proteins.
C) DNA makes up the individual sugar-phosphate-base units of a protein.
D) DNA molecules are the enzymes that synthesize proteins.
E) Proteins store the information needed to make DNA.
Q:
The building blocks of DNA are:
A) amino acids.
B) enzymes.
C) phosphate groups.
D) nucleotides.
E) bases.
Q:
How is the information that specifies a protein stored in DNA?
A) in the arrangement of the sugar-phosphate chain
B) in the types of chemical bonds holding bases together
C) in the sequence of bases
D) in the orientation of the double strands
Q:
Which of the following is not a component of DNA nucleotides?
A) deoxyribose
B) a phosphate group
C) adenine
D) arginine
E) guanine
Q:
Why are the strands of DNA said to be complementary to each other?
A) The sugar-phosphate chains are running in opposite directions.
B) The sugar-phosphate chains of each strand are identical.
C) Both strands can have any of four possible bases attached.
D) All the bases of one strand are paired up with their complementary bases on the other strand.
Q:
Watson and Crick discovered:
A) the structure of DNA.
B) that DNA is the genetic material.
C) X-ray crystallography.
D) that genetic information resides on chromosomes.
Q:
It was primarily the X-ray diffraction work on DNA done by ________ that allowed Watson and Crick to deduce the structure of DNA.
A) Louis Pasteur
B) Gregor Mendel
C) Rosalind Franklin
D) T.H. Morgan
Q:
How are X rays used in the technique of X-ray diffraction?
A) The scattering of X rays by a purified form of a molecule reveals its structure.
B) DNA strands are separated by X-ray energy, revealing the order of bases.
C) Cells are broken open to release chromosomes by being bombarded with X rays.
D) The X rays are used to mutate DNA to determine the location of genes.
E) Enzymes are destroyed by X rays, revealing the order of steps in metabolism.
Q:
Which information was determined about DNA based on X-ray diffraction data?
A) Each gene encodes one enzyme.
B) There are four different bases on the nucleotides.
C) Point mutations change a single location in the genome.
D) DNA has a helical structure.
E) Chromosomes are made of DNA.
Q:
Watson and Crick's model of the structure of DNA was published in:
A) 1953.
B) 1961.
C) 1923.
D) 1949.
E) 1975.
Q:
Which of these individuals are credited with the discovery of the structure of DNA?
A) Rosalind Franklin and Maurice Wilkins
B) Gregor Mendel and T.H. Morgan
C) James Watson and Francis Crick
D) Louis Pasteur
Q:
The location of genetic information on chromosomes had been established beyond any doubt by:
A) 1880.
B) 1850.
C) 1890.
D) 1920.
E) 1900.
Q:
Refer to the figure below, and then answer the question that follows. A mistake is made during DNA replication, so there is incorrect base pairing in the DNA. Depending on how the replication repair mechanism fixes this problem, a point mutation may or may not result. What might the replication repair mechanism do, and would it result in a point mutation?A) The repair mechanism might replace the T with a C, which would result in a point mutation.B) The repair mechanism might replace the G with an A, which would result in a point mutation.C) The repair mechanism might replace the G with a C, which would result in a point mutation.D) The repair mechanism might replace the T with a G, which would not result in a point mutation.
Q:
Refer to the figure below, and then answer the question that follows.A G-C base pair holds the double helix together more strongly than an A-T base pair. Can you suggest a reason why?
Q:
Individuals who have a disease such as melanoma do not necessarily have offspring with melanoma. However, individuals with Huntington disease often do pass it on to their offspring. What accounts for the difference in the heritability of the two diseases?
Q:
What mechanism can introduce new genetic information into a species?
Q:
Suppose you are a biologist trying to discover the process by which DNA copies itself. You grow cells in a culture that contains a special isotope of nitrogen, N-15, which will become part of any new DNA the cell makes. After one generation, you analyze the DNA and find all the DNA has some N-15 in it. You then take those cells and grow them for another generation in a culture with the normal isotope of nitrogen, N-14, and find that half of the DNA has some N-15 in it and half of it has only N-14. From this information, what can you infer is the process by which DNA replicates?
Q:
Write the sequence of the DNA strand complementary to a strand with the sequence AAATGCC.
Q:
Describe what happens to the two parent strands of DNA during DNA replication.
Q:
Early in the twentieth century, many biologists believed that the genetic material of living organisms had to be made of proteinit seemed that only proteins had the complexity to store the vast amount of genetic information that organisms need. How is a relatively simple molecule such as DNA capable of storing large amounts of genetic information? Another requirement for genetic material is that it will sometimes need to be replicated. How does DNA satisfy this requirement?
Q:
Mutations will not be passed on to the next generation if they occur in ________ cells.
Q:
Refer to the figure below, and then answer the question that follows.Nondisjunction in meiosis gives rise to gametes with abnormal chromosome numbers. Which event is likely to produce a higher percentage of abnormal gametes?A) failure of homologous chromosomes to separate at meiosis IB) failure of homologous chromosomes to separate at meiosis IIC) failure of sister chromatids to separate at meiosis ID) failure of sister chromatids to separate at meiosis IIE) failure of sister chromatids to separate at mitosis
Q:
Refer to the figure below, and then answer the question that follows. The last members of the Russian Royal Family were executed during the Russian Revolution. Assume the revolution never took place and Alexis, son of Czar Nicholas II and Alexandra, survived and married into the British Royal Family. What is the probability that his children would have hemophilia? What is the probability his children would be carriers for hemophilia?
Q:
Explain what causes aneuploidy.
Q:
Phenylketonuria is the most commonly inherited genetic disorder that affects nervous system development. It occurs in 1 out of every 10,000 births in the United States and Europe. How would you design a study to determine if phenylketonuria is an autosomal dominant or autosomal recessive disorder? How would you be able to determine if it is dominant or recessive?
Q:
Duchenne muscular dystrophy is a recessive disorder resulting in a wasting away of the muscles. How would you design a study to determine if the disorder is X-linked or autosomal? How would you be able to determine if it is X-linked or autosomal?
Q:
Hemophelia is an X-linked recessive disorder. A mother without the allele and a father with the allele have a daughter. The daughter then marries a man with hemophilia. What is the genotype of the daughter? What is the probability that the daughter's children will develop the disease?
Q:
Explain why a female can be heterozygous for an X-linked gene but a male cannot.
Q:
________ is the condition when an individual has three copies of chromosome 21.
Q:
The condition in which an organism has more than two sets of chromosomes is called ________, while having either more or fewer than the normal number of a particular chromosome is called ________.
Q:
You have studied the presence of a trait in the members of three generations of a family. With this information, you constructed a ________ to track how the trait was passed down through the generations.
Q:
A person with only one allele for a recessive condition who does not have the condition is called a ________.
Q:
Hemophilia, Duchenne muscular dystrophy, and color blindness are examples of ________ disorders.
Q:
Match the following.A) aneuploidyB) nondisjunctionC) duplicationD) translocationE) deletionThis has been involved in producing gene families and has been vital to evolution.
Q:
Non-homologous chromosomes have exchanged parts.
Q:
Match the following.A) aneuploidyB) nondisjunctionC) duplicationD) translocationE) deletionThis produces cri-du-chat syndrome.
Q:
Match the following.A) aneuploidyB) nondisjunctionC) duplicationD) translocationE) deletionOnly 1 percent of human embryos with this condition survive.
Q:
Match the following.A) aneuploidyB) nondisjunctionC) duplicationD) translocationE) deletionThis event may occur during meiosis I or meiosis II.
Q:
A single nondisjunction event results in some gametes with more chromosomes and some gametes with fewer chromosomes.
Q:
Polyploidy is better tolerated in plants than in animals.
Q:
If one of your parents has Huntington disease and is heterozygous for the disorder, you have a 50 percent chance of inheriting the disease.
Q:
A carrier for a genetic disorder will pass the allele to all of their offspring.
Q:
A person must have two alleles for hemoglobin S in order to suffer from sickle-cell anemia.
Q:
Women do not express X-linked recessive characters.
Q:
A chromosome that has been broken and has lost a section has had a/an:
A) aneuploidy.
B) inversion.
C) deletion.
D) duplication.
E) translocation.
Q:
Cri-du-chat syndrome babies are mentally challenged and have an abnormal larynx that makes sounds like the cry of a cat. This disorder is due to a/an:
A) deletion in chromosome 5.
B) inversion in chromosome 2.
C) translocation between chromosome 9 and 22.
D) duplication in chromosome 7.
E) trisomy 21.
Q:
Which of the following is a transfer of genes between non-homologous chromosomes?
A) duplication
B) crossing over
C) inversion
D) deletion
E) translocation
Q:
A karyotype you are viewing shows an extra piece of chromosome 1 attached to chromosome 22. What type of abnormality caused this?
A) inversion
B) deletion
C) translocation
D) nondisjunction
E) sex-linked
Q:
What is a possible cause of the chromosomal aberration called a "duplication"?
A) unequal crossing over
B) exchange between non-homologous chromosomes
C) a chromosome fragment that breaks off and does not rejoin any chromosome
D) breaking of a chromosome fragment, then rejoining in a flipped orientation
E) nondisjunction
Q:
When a fragment breaks from a chromosome and rejoins it, in a flipped orientation, the result is called a/an:
A) deletion.
B) polyploidy.
C) inversion.
D) aneuploidy.
E) translocation.
Q:
Which of the following combinations of chromosomes would be found in a person afflicted with Turner syndrome?
A) XXY
B) XYY
C) XX
D) XY
E) XO
Q:
Nondisjunction in somatic cells can result in aneuploid cells. This may give rise to:
A) Down syndrome.
B) Turner syndrome.
C) Klinefelter syndrome.
D) cancer.
E) cri-du-chat syndrome.
Q:
What single attribute determines that a human fetus is male?
A) the absence of a second X chromosome
B) the absence of a Y chromosome
C) the presence of a Y chromosome
D) the presence of two X chromosomes
Q:
A karyotype reveals that a woman is carrying a fetus that has 47 chromosomes. The test reveals that the genotype of the fetus is XXY. Which of the following statements is correct?
A) The fetus has Down syndrome, and most likely a nondisjunction event occurred in the mother during egg formation.
B) The fetus has Turner syndrome, and most likely a nondisjunction event occurred in the mother during egg formation.
C) The fetus has Klinefelter syndrome.
D) The fetus has an autosomal disorder.
Q:
Which condition or disease is caused by aneuploidy?
A) sickle-cell anemia
B) hemophilia
C) malaria
D) color blindness
E) Down syndrome