Molecular Biology exam test quizzes
and answers graded A+
When the base composition of double-stranded DNA from a new species of bacteria was
determined, 20% of the bases were found to be adenine. What is the percentage of cytosine in the
DNA of this organism? - ANS✅✅30%
the sequence of one strand of DNA is 5'-GCTTTAG-3'. What is the sequence of the complementary
strand? - ANS✅✅5'-CTAAAGC-3'
what is the process of making an RNA strand from a DNA template called? - ANS✅✅transcription
what is tRNA? - ANS✅✅a molecule that incorporates a specific amino acid into the growing
protein when it recognizes a specific codon
in a complementation test, two strains of fruit flies with mutations that cause the flies not to
produce any wings are crossed. If the F1 offspring have normal wings, what can be concluded? -
ANS✅✅the mutations are not in the same gene
you used x-rays to generate mutations in Neurospora Crassa. After analyzing the mutants a-f, you
realized that they appear to be working in the same pathway. To estimate if some of the mutations
are within the same gene, you crossed all the mutants with each other leading to the
complementation matrix shown below. Which of the following conclusions can be drawn from the
matrix? - ANS✅✅mutations a and d are likely within the same gene
where in a non-dividing cell can chromosomes be found? - ANS✅✅nucleus
the pedigree below tracks the presence of dimples within a family. Assume that gene "d" is
responsible for the family trait and that having dimples is the dominant allele "D" of the autosomal
trait ("d" is the recessive trait for not having dimples). Which of the following genotype - person
combinations is possible? - ANS✅✅III-2: Dd
the ability to roll the tongue is a dominant trait. In the pedigree below, solid symbols represent
"rollers" and open symbols "non-rollers". For analysis purposes, you can use "R" representing the
dominant allele for roller and "r" the allele for the recessive trait. Which person-roller combination
within this pedigree can't be explained by the classical passing on of alleles from the parents to the
children? - ANS✅✅C9
, In families where both parents are heterozygous for a recessive trait, what is the probability of their
having a child with the homozygous recessive genotype? - ANS✅✅1/4
you are using Mendel's pees and start with a cross between AA and aa. If you let the progreny of the
cross self-fertilize, what will be the proportion of heterozygotes in the F2 progeny? - ANS✅✅1/2
Parents heterozygous for a recessive allele are called: - ANS✅✅carriers
a woman with keratosis, a skin condition caused by a rare dominant allele (assume she is
heterozygous), marries a normal man, and they have two children. What is the probability that both
children are normal? - ANS✅✅1/4
the longitudinal halves of a chromosome that has undergone replication are called: -
ANS✅✅chromatids
the process of cell division that ensures that each of the two daughter cells receives a chromosome
complement identical to the complement of the parent cell is known as: - ANS✅✅mitosis
the portion of the cell cycle during which the chromosomes are replicated is called: - ANS✅✅S
In chromatin, 110Å fibers condense in high salt concentration to form the next ordered structure,
known as the: - ANS✅✅30-nm fiber
which of the following types of inheritance is characterized by an affected father who marries a
healthy woman and has all affected daughters but no affected sons? - ANS✅✅X-linked dominant
common red-green color blindness is an X-linked trait. A woman whose father is color blind married
a normal man and they have one son. What is the probability that he is color blind? - ANS✅✅1/2
albinism is a recessive trait that results from lack of the skin pigment melanin. Two normally
pigmented parents have a child with albinism. Given that the normal allele is A and the albino allele
is a, what is the probability that the parents will have another child that is a carrier of the albino
allele? - ANS✅✅2/3
and answers graded A+
When the base composition of double-stranded DNA from a new species of bacteria was
determined, 20% of the bases were found to be adenine. What is the percentage of cytosine in the
DNA of this organism? - ANS✅✅30%
the sequence of one strand of DNA is 5'-GCTTTAG-3'. What is the sequence of the complementary
strand? - ANS✅✅5'-CTAAAGC-3'
what is the process of making an RNA strand from a DNA template called? - ANS✅✅transcription
what is tRNA? - ANS✅✅a molecule that incorporates a specific amino acid into the growing
protein when it recognizes a specific codon
in a complementation test, two strains of fruit flies with mutations that cause the flies not to
produce any wings are crossed. If the F1 offspring have normal wings, what can be concluded? -
ANS✅✅the mutations are not in the same gene
you used x-rays to generate mutations in Neurospora Crassa. After analyzing the mutants a-f, you
realized that they appear to be working in the same pathway. To estimate if some of the mutations
are within the same gene, you crossed all the mutants with each other leading to the
complementation matrix shown below. Which of the following conclusions can be drawn from the
matrix? - ANS✅✅mutations a and d are likely within the same gene
where in a non-dividing cell can chromosomes be found? - ANS✅✅nucleus
the pedigree below tracks the presence of dimples within a family. Assume that gene "d" is
responsible for the family trait and that having dimples is the dominant allele "D" of the autosomal
trait ("d" is the recessive trait for not having dimples). Which of the following genotype - person
combinations is possible? - ANS✅✅III-2: Dd
the ability to roll the tongue is a dominant trait. In the pedigree below, solid symbols represent
"rollers" and open symbols "non-rollers". For analysis purposes, you can use "R" representing the
dominant allele for roller and "r" the allele for the recessive trait. Which person-roller combination
within this pedigree can't be explained by the classical passing on of alleles from the parents to the
children? - ANS✅✅C9
, In families where both parents are heterozygous for a recessive trait, what is the probability of their
having a child with the homozygous recessive genotype? - ANS✅✅1/4
you are using Mendel's pees and start with a cross between AA and aa. If you let the progreny of the
cross self-fertilize, what will be the proportion of heterozygotes in the F2 progeny? - ANS✅✅1/2
Parents heterozygous for a recessive allele are called: - ANS✅✅carriers
a woman with keratosis, a skin condition caused by a rare dominant allele (assume she is
heterozygous), marries a normal man, and they have two children. What is the probability that both
children are normal? - ANS✅✅1/4
the longitudinal halves of a chromosome that has undergone replication are called: -
ANS✅✅chromatids
the process of cell division that ensures that each of the two daughter cells receives a chromosome
complement identical to the complement of the parent cell is known as: - ANS✅✅mitosis
the portion of the cell cycle during which the chromosomes are replicated is called: - ANS✅✅S
In chromatin, 110Å fibers condense in high salt concentration to form the next ordered structure,
known as the: - ANS✅✅30-nm fiber
which of the following types of inheritance is characterized by an affected father who marries a
healthy woman and has all affected daughters but no affected sons? - ANS✅✅X-linked dominant
common red-green color blindness is an X-linked trait. A woman whose father is color blind married
a normal man and they have one son. What is the probability that he is color blind? - ANS✅✅1/2
albinism is a recessive trait that results from lack of the skin pigment melanin. Two normally
pigmented parents have a child with albinism. Given that the normal allele is A and the albino allele
is a, what is the probability that the parents will have another child that is a carrier of the albino
allele? - ANS✅✅2/3
