1
genetics exam 4 lectures Questions
and Answers (100% Correct
Answers) Already Graded A+
gene interaction Ans: refers to ways that genes and alleles of
genes interact to influence phenotype
© 2026 Assignment
Expression of a trait may depend on Ans: the interaction of >1
gene and/or the interaction of genes with other factors (e.g.,
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environmental)
Expert
Single genes can affect Ans: multiple distinct traits
An individual is penetrant for a trait when Ans: the phenotype
is consistent with the genotype
non-penetrant Ans: An individual that does not produce the
phenotype generally associated with a genotype
incomplete penetrance Ans: Traits for which non-penetrant
individuals routinely occur are said to display
what kind of penetrace does polydactyly display Ans:
incomplete penetrance
(autosomal dominant, dominant allele is non-penetrant in 25-
30% of individuals carrying it)
variable expressivity Ans: individuals who carry the alleles for
a trait show a phenotype but to a varying degree of severity
, 2
waardenburg sydnrome is an example of what Ans: variable
expressivity (autosomal dominant condition w/ 4 principle
features, each family member with Waardenburg syndrome has
same genotype but shows a different combination of
symptoms)
Position Effects Ans: The physical location of a gene may
influence its expression
Position effect variegation (PEV) in Drosophila Ans: illustrates
the effect of chromatin compaction on gene expression
© 2026 Assignment
(Chromosomal inversion in fruit flies that resulted in
variegated eye color, white gene moved from its normal
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position to a region near heterochromatin, Heterochromatin
Expert
spreads outward (variably).)
Environmental effects Ans: result from the influence of
environmental factors on the expression of genes and the
phenotype of the organism
example of environmental effect Ans: ch allele enzyme in
Himalayan rabbits is temperature-sensitive
Pleiotropy Ans: the alteration of multiple distinct traits by a
mutation in a single gene
Pleiotropic effects of a mutant protein product are often seen
in studies of Ans: development (ex: in Drosophila, juvenile
hormone (JH) influences numerous attributes of development
and reproduction such as body size, development time, sexual
maturity, and others)
Pleiotropic Effects Ans: Marfan syndrome in humans is caused
by an autosomal dominant mutation in the fibrillin gene
(Fibrillin is key structural component of microfibrils, essential
for elastic fibers and CT)
, 3
Single-gene trait Ans: the observation that inherited variation
for one gene can produce a mutant phenotype rather than the
wild type (this is not the case for many traits as they may be
influenced by multiple genes)
Three Genes Involved in Drosophila Eye Color Ans: brown gene
(bb): brown eyes
vermillion gene (vv): bright red eyes
© 2026 Assignment
white gene:flies without white gene have white eyes
Three Distinct Types of Genetic Pathways Ans: -Biosynthetic
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pathways
Expert
-Signal transduction pathways
-Developmental pathways
Biosynthetic pathways Ans: are networks of interacting genes
that produce a molecular compound as their endpoint
-consist of sequential steps
-Completion of one step generates the substrate for the next
step in the pathway
-completion of every step is necessary to produce the end
product
Developmental pathways Ans: direct growth, development,
and differentiation of body parts and structures
-Expression of specific genes results in a genetic cascade
genetics exam 4 lectures Questions
and Answers (100% Correct
Answers) Already Graded A+
gene interaction Ans: refers to ways that genes and alleles of
genes interact to influence phenotype
© 2026 Assignment
Expression of a trait may depend on Ans: the interaction of >1
gene and/or the interaction of genes with other factors (e.g.,
Guru01 - Stuvia
environmental)
Expert
Single genes can affect Ans: multiple distinct traits
An individual is penetrant for a trait when Ans: the phenotype
is consistent with the genotype
non-penetrant Ans: An individual that does not produce the
phenotype generally associated with a genotype
incomplete penetrance Ans: Traits for which non-penetrant
individuals routinely occur are said to display
what kind of penetrace does polydactyly display Ans:
incomplete penetrance
(autosomal dominant, dominant allele is non-penetrant in 25-
30% of individuals carrying it)
variable expressivity Ans: individuals who carry the alleles for
a trait show a phenotype but to a varying degree of severity
, 2
waardenburg sydnrome is an example of what Ans: variable
expressivity (autosomal dominant condition w/ 4 principle
features, each family member with Waardenburg syndrome has
same genotype but shows a different combination of
symptoms)
Position Effects Ans: The physical location of a gene may
influence its expression
Position effect variegation (PEV) in Drosophila Ans: illustrates
the effect of chromatin compaction on gene expression
© 2026 Assignment
(Chromosomal inversion in fruit flies that resulted in
variegated eye color, white gene moved from its normal
Guru01 - Stuvia
position to a region near heterochromatin, Heterochromatin
Expert
spreads outward (variably).)
Environmental effects Ans: result from the influence of
environmental factors on the expression of genes and the
phenotype of the organism
example of environmental effect Ans: ch allele enzyme in
Himalayan rabbits is temperature-sensitive
Pleiotropy Ans: the alteration of multiple distinct traits by a
mutation in a single gene
Pleiotropic effects of a mutant protein product are often seen
in studies of Ans: development (ex: in Drosophila, juvenile
hormone (JH) influences numerous attributes of development
and reproduction such as body size, development time, sexual
maturity, and others)
Pleiotropic Effects Ans: Marfan syndrome in humans is caused
by an autosomal dominant mutation in the fibrillin gene
(Fibrillin is key structural component of microfibrils, essential
for elastic fibers and CT)
, 3
Single-gene trait Ans: the observation that inherited variation
for one gene can produce a mutant phenotype rather than the
wild type (this is not the case for many traits as they may be
influenced by multiple genes)
Three Genes Involved in Drosophila Eye Color Ans: brown gene
(bb): brown eyes
vermillion gene (vv): bright red eyes
© 2026 Assignment
white gene:flies without white gene have white eyes
Three Distinct Types of Genetic Pathways Ans: -Biosynthetic
Guru01 - Stuvia
pathways
Expert
-Signal transduction pathways
-Developmental pathways
Biosynthetic pathways Ans: are networks of interacting genes
that produce a molecular compound as their endpoint
-consist of sequential steps
-Completion of one step generates the substrate for the next
step in the pathway
-completion of every step is necessary to produce the end
product
Developmental pathways Ans: direct growth, development,
and differentiation of body parts and structures
-Expression of specific genes results in a genetic cascade
