Genetics Final Exam: Comprehensive Solutions
and Explanations with Tested Strategies Tailored for
Top Grades - In-Depth Answer Analysis Included
In Drosophila, both fushi tarazu (ftz) and engrailed (eng) genes encode homeobox
transcription factors and are capable of eliciting the expression of other genes. Both genes
work at about the same time during development and in the same region to specify cell fate
in body segments.To discover if ftz regulates the expression of engrailed; if engrailed
regulates ftz; or if both are regulated by another gene, you perform a mutant analysis. In ftz
embryos (ftz/ftz) engrailed protein is absent; in engrailed embryos (eng/eng) ftz expression
is normal. What does this tell you about the regulation of these two genes - does the
engrailed gene regulate ftz, or does the ftz gene regulate engrailed? You should provide an
explanation for your answer. - correct answer- -The ftz gene product regulates expression
of the eng gene either directly / indirectly because if it is ftz deficient it doesn't express the
eng gene, which indicates that the expression of eng depends on ftz. This can be shown in
an en/en embryo that expresse ftz normally even without eng product. So ftz expression is
idnependent of eng expression.
Darwin's theory of evolution (via natural selection) requires that - correct answer- -
variation exists among individuals in a population.
survival will vary among individuals in a population.
organisms demonstrate similar phenotypes as their parents.
reproductive success will vary among individuals in a population.
When an organism is able to better survive in an environment due to a new mutation, we
can conclude that - correct answer- -the mutation occurred randomly and was not caused
by the environment.
,A high school student is trying to find evidence that evolution can "repeat itself," as she is
writing a report on this topic. What examples could she cite to support her thesis that
evolution can be repeated? - correct answer- -
A gene-inactivating mutation can rise to a high frequency in a population when a change in
habitat or lifestyle makes the function of that specific gene unnecessary. - correct answer-
-True
A researcher is studying different instances of gene duplication in mice. In one instance, he
notes that a duplicated gene has been completely inactivated. This is an example of -
correct answer- -
Which of the following is a source of genetic variation that can play a role in evolution? -
correct answer- -nonsynonymous substitutions
gene duplication
horizontal DNA transfer
polyploidy
Which of the following forces would cause a decrease in genetic variation in a single
population of organisms (belonging to the same species)? - correct answer- -directional
selection
You are studying a new strain of bacteria. You discover that its genome contains some
genes that are not found in any form in its most recent ancestor. You suspect - correct
answer- -horizontal gene transfer
, According to the neutral theory of evolution - correct answer- -most fixed mutations in the
DNA sequence of a protein-coding gene do not change the function of the protein
A study of the geographic distribution of the HbS allele in Africa demonstrated that -
correct answer- -heterozygotes for this allele have a survival advantage in areas where
malaria occurs.
If a tRNA molecule carries a glutamic acid (Glu), what are the two possible anticodon
sequences that it could contain? Be specific about the 5′ and 3′ ends. - correct answer- -3'
- cuu - 5' or 3' - cuc - 5'
A protein called actin consists of 376 amino acids. The mRNA for actin must be longer than
- correct answer- -1128 nucleotides.
The following statements describe translation. Determine if the statement applies to only
prokaryotes, to only eukaryotes, or to both.
The first tRNA used is charged with a formyl methionine. - correct answer- -prokaryotes
In the lac operon, the CAP site is located next to the ________. When both lactose and
glucose are present, this leads to a rate of transcription that is ________. - correct answer- -
promoter, low
Suppose you discover a new form of a nucleic acid, XNA. Like DNA, it is double-stranded.
You are interested in its mode of replication, so you label parental XNA and then allow that
XNA to replicate in the presence of unlabeled bases. After one round of replication, you find
the parental XNA intact with both strands labeled and the new XNA with both strands
unlabeled. What can you infer? - correct answer- -Unlike DNA, XNA replicates
conservatively
Which statement about epigenetics is false? - correct answer- -Epigenetic changes cannot
be inherited.
and Explanations with Tested Strategies Tailored for
Top Grades - In-Depth Answer Analysis Included
In Drosophila, both fushi tarazu (ftz) and engrailed (eng) genes encode homeobox
transcription factors and are capable of eliciting the expression of other genes. Both genes
work at about the same time during development and in the same region to specify cell fate
in body segments.To discover if ftz regulates the expression of engrailed; if engrailed
regulates ftz; or if both are regulated by another gene, you perform a mutant analysis. In ftz
embryos (ftz/ftz) engrailed protein is absent; in engrailed embryos (eng/eng) ftz expression
is normal. What does this tell you about the regulation of these two genes - does the
engrailed gene regulate ftz, or does the ftz gene regulate engrailed? You should provide an
explanation for your answer. - correct answer- -The ftz gene product regulates expression
of the eng gene either directly / indirectly because if it is ftz deficient it doesn't express the
eng gene, which indicates that the expression of eng depends on ftz. This can be shown in
an en/en embryo that expresse ftz normally even without eng product. So ftz expression is
idnependent of eng expression.
Darwin's theory of evolution (via natural selection) requires that - correct answer- -
variation exists among individuals in a population.
survival will vary among individuals in a population.
organisms demonstrate similar phenotypes as their parents.
reproductive success will vary among individuals in a population.
When an organism is able to better survive in an environment due to a new mutation, we
can conclude that - correct answer- -the mutation occurred randomly and was not caused
by the environment.
,A high school student is trying to find evidence that evolution can "repeat itself," as she is
writing a report on this topic. What examples could she cite to support her thesis that
evolution can be repeated? - correct answer- -
A gene-inactivating mutation can rise to a high frequency in a population when a change in
habitat or lifestyle makes the function of that specific gene unnecessary. - correct answer-
-True
A researcher is studying different instances of gene duplication in mice. In one instance, he
notes that a duplicated gene has been completely inactivated. This is an example of -
correct answer- -
Which of the following is a source of genetic variation that can play a role in evolution? -
correct answer- -nonsynonymous substitutions
gene duplication
horizontal DNA transfer
polyploidy
Which of the following forces would cause a decrease in genetic variation in a single
population of organisms (belonging to the same species)? - correct answer- -directional
selection
You are studying a new strain of bacteria. You discover that its genome contains some
genes that are not found in any form in its most recent ancestor. You suspect - correct
answer- -horizontal gene transfer
, According to the neutral theory of evolution - correct answer- -most fixed mutations in the
DNA sequence of a protein-coding gene do not change the function of the protein
A study of the geographic distribution of the HbS allele in Africa demonstrated that -
correct answer- -heterozygotes for this allele have a survival advantage in areas where
malaria occurs.
If a tRNA molecule carries a glutamic acid (Glu), what are the two possible anticodon
sequences that it could contain? Be specific about the 5′ and 3′ ends. - correct answer- -3'
- cuu - 5' or 3' - cuc - 5'
A protein called actin consists of 376 amino acids. The mRNA for actin must be longer than
- correct answer- -1128 nucleotides.
The following statements describe translation. Determine if the statement applies to only
prokaryotes, to only eukaryotes, or to both.
The first tRNA used is charged with a formyl methionine. - correct answer- -prokaryotes
In the lac operon, the CAP site is located next to the ________. When both lactose and
glucose are present, this leads to a rate of transcription that is ________. - correct answer- -
promoter, low
Suppose you discover a new form of a nucleic acid, XNA. Like DNA, it is double-stranded.
You are interested in its mode of replication, so you label parental XNA and then allow that
XNA to replicate in the presence of unlabeled bases. After one round of replication, you find
the parental XNA intact with both strands labeled and the new XNA with both strands
unlabeled. What can you infer? - correct answer- -Unlike DNA, XNA replicates
conservatively
Which statement about epigenetics is false? - correct answer- -Epigenetic changes cannot
be inherited.
