Bio 322 Exam 1 Questions With Complete Solutions
An environmentally caused condition whose symptoms are
similar to those of a known inherited disorder is called a(n)
phenocopy
A(n) _______ allele may result in a phenotypic class that does
not survive long enough to reproduce.
lethal
Which of the following statements describe mitochondrial
DNA?
High exposure to oxygen free radicals
Inherited from the mother only
Carries 37 genes
Fewer types of DNA repair than nuclear DNA
No crossing over
In epistasis, the blocked gene is expressed normally, but the
product of the modifier gene inactivates it.
true
An allele combination that produces a phenotype in everyone
who inherits it is not penetrant
false
A phenotype is variably expressive if symptoms vary in
intensity among different people.
true
,On a molecular level, genetic heterogeneity occurs when a
single protein affects different body parts, participates in more
than one biochemical reaction.
false
Phenocopies are genetically caused traits that appear to be
inherited.
false
What is the best explanation for the inheritance pattern shown in
the pedigree below?
mitochondrial inheritance
Tanisha and Tawanda are twins but do not look alike. They are
the result of fertilization of
two oocytes by two sperm cells.
The inner cell mass
gives rise to the embryo
An embryo develops rudiments of all organs by week
__________ of prenatal development.
8
,A(n) __________ cross yields a genotypic ratio of 1:2:1 and a
phenotypic ratio of 3:1.
monohybrid
Sickle cell disease is inherited as an autosomal recessive trait.
The genotype of an individual with sickle cell disease is
homozygous recessive
The phenotypic ratio expected from a dihybrid cross is
9:3:3:1
Ian and Bryony are both carriers for two autosomal recessive
disorders, PKU (chromosome 12) and cystic fibrosis
(chromosome 7). They are expecting a daughter. What is the
probability that she will have PKU but not CF?
3/16
Cystic fibrosis is autosomal recessive. This means that
__________
both sexes can be affected and can "skip" generations through
carriers.
For two traits A and B with two alleles each, the genotypes of
the gametes that a double heterozygote would produce are
AB, Ab, aB, ab.
Which of the following represents a monohybrid cross?
Bb x Bb
Variants of a gene are called
, alleles
Cells differentiate by
expressing different subsets of genes
Humans belong to domain __________, which is distinguished
by cells that have __________.
Eukarya; organelles
Cells contain twice the normal number of independent
chromosomes briefly during
anaphase
Egg cells are
haploid germ cells
After meiosis I, the number of chromosomes is __________ that
of a somatic cell.
half
Primary spermatocytes develop from the division of
spermatogonia.
In the first step in oogenesis
an oogonium accumulates cytoplasm and DNA replicates.
Some combinations of recessive alleles cause problems so
severe that a fetus may cease to develop. Such lethal allele
combinations appear to alter Mendelian ratios because
homozygotes for the lethal allele do not appear as a progeny
class.
An environmentally caused condition whose symptoms are
similar to those of a known inherited disorder is called a(n)
phenocopy
A(n) _______ allele may result in a phenotypic class that does
not survive long enough to reproduce.
lethal
Which of the following statements describe mitochondrial
DNA?
High exposure to oxygen free radicals
Inherited from the mother only
Carries 37 genes
Fewer types of DNA repair than nuclear DNA
No crossing over
In epistasis, the blocked gene is expressed normally, but the
product of the modifier gene inactivates it.
true
An allele combination that produces a phenotype in everyone
who inherits it is not penetrant
false
A phenotype is variably expressive if symptoms vary in
intensity among different people.
true
,On a molecular level, genetic heterogeneity occurs when a
single protein affects different body parts, participates in more
than one biochemical reaction.
false
Phenocopies are genetically caused traits that appear to be
inherited.
false
What is the best explanation for the inheritance pattern shown in
the pedigree below?
mitochondrial inheritance
Tanisha and Tawanda are twins but do not look alike. They are
the result of fertilization of
two oocytes by two sperm cells.
The inner cell mass
gives rise to the embryo
An embryo develops rudiments of all organs by week
__________ of prenatal development.
8
,A(n) __________ cross yields a genotypic ratio of 1:2:1 and a
phenotypic ratio of 3:1.
monohybrid
Sickle cell disease is inherited as an autosomal recessive trait.
The genotype of an individual with sickle cell disease is
homozygous recessive
The phenotypic ratio expected from a dihybrid cross is
9:3:3:1
Ian and Bryony are both carriers for two autosomal recessive
disorders, PKU (chromosome 12) and cystic fibrosis
(chromosome 7). They are expecting a daughter. What is the
probability that she will have PKU but not CF?
3/16
Cystic fibrosis is autosomal recessive. This means that
__________
both sexes can be affected and can "skip" generations through
carriers.
For two traits A and B with two alleles each, the genotypes of
the gametes that a double heterozygote would produce are
AB, Ab, aB, ab.
Which of the following represents a monohybrid cross?
Bb x Bb
Variants of a gene are called
, alleles
Cells differentiate by
expressing different subsets of genes
Humans belong to domain __________, which is distinguished
by cells that have __________.
Eukarya; organelles
Cells contain twice the normal number of independent
chromosomes briefly during
anaphase
Egg cells are
haploid germ cells
After meiosis I, the number of chromosomes is __________ that
of a somatic cell.
half
Primary spermatocytes develop from the division of
spermatogonia.
In the first step in oogenesis
an oogonium accumulates cytoplasm and DNA replicates.
Some combinations of recessive alleles cause problems so
severe that a fetus may cease to develop. Such lethal allele
combinations appear to alter Mendelian ratios because
homozygotes for the lethal allele do not appear as a progeny
class.
