MICROBIO 303 Exam Questions and
answers graded A+
If two chromosomes of a species are the same length and have similar centromere placements but
are not homologous, then what is different about them? - ANS✅✅They do not contain similar
genes
"Crossing over" between maternal and paternal chromosomes takes place during - ANS✅✅meiosis
1
A place in the eukaryotic cell cycle at which a "decision" is made whether to proceed through the cell
cycle or to arrest cell cycle progression is generally known as - ANS✅✅a checkpoint
Which step of meiosis contributes to significant genetic variation? - ANS✅✅Prophase 1
In somatic cells, sister chromatids exist when - ANS✅✅exist in the G2 stage of the cell cycle
Tight pairing of homologous chromosomes during meiosis is called - ANS✅✅synapsis
a form of a gene - ANS✅✅allele
What is the probability that in an organism with a haploid number of 10, an egg will be formed that
contains all 10 chromosomes whose centromeres were derived from maternal homologs? -
ANS✅✅(1/2)^10
In each one of Mendel's dihybrid crosses, what was the common trend? - ANS✅✅the phenotypes
of the F2 generation segregated in a 9:3:3:1 ratio
In the cross (AaBb x AaBb), the genotype aabb should occur at what frequency? - ANS✅✅1/16
A 9:3:3:1 ratio of phenotypes in the F2 generation of a dihybrid cross - ANS✅✅indicates that the
dihybrid cross is basically equivalent to two independent monohybrid crosses
, Albinism in humans is inherited as a simple autosomal recessive trait. Two normal parents have five
children and one is albino. If the dominant and recessive allels for albinism are designated as "A" and
"a" respectively, then the genotypes of the parents are most likely: - ANS✅✅Mom: Aa Dad: Aa
A tall, violet plant is crossed with a dwarf, white plant and all of the F1 offspring are tall,violet. The
F1 plants are selfed to produce the F2 generation. What fraction of the F2 generation would you
expect to be dwarf, violet? - ANS✅✅3/16
How many different types of gametes can be formed by an individual of the following genotype:
AaBbCcDdEEFF? - ANS✅✅2^4=16
Consider three independently assorting genes A,B, and C. What is the probability of obtaining an
offspring that is AaBBCc from parents that are AABbCc and AaBbCc? - ANS✅✅1/16
A woman and a man are both heterozygous for freckles, which is the dominant condition. If they
have one child, what are the chances that it will have freckles? - ANS✅✅75%
With incomplete dominance, a .likely F2 phenotypic ratio in a monohybrid cross would be -
ANS✅✅1:2:1
involves heterozygotes displaying a blending of phenotypes - ANS✅✅Incomplete dominance
A condition in which one gene influences the expression of another gene is called -
ANS✅✅Epistasis
If a child is blood type A and the mother is blood type A, what is the blood type of the father? -
ANS✅✅Can't tell
Suppose an allele, b, of a sex-linked gene is recessive and embryonic lethal. A man marries a woman
who is heterozygous for this gene. If this couple had a large number of children, what would be the
predicted ratio of male children to female children? - ANS✅✅1:2
A given genotype that produces a different phenotype in males versus females - ANS✅✅Sex-
influenced inheritance
When two genes fail to assort independently, the term normally applied is - ANS✅✅linkage
answers graded A+
If two chromosomes of a species are the same length and have similar centromere placements but
are not homologous, then what is different about them? - ANS✅✅They do not contain similar
genes
"Crossing over" between maternal and paternal chromosomes takes place during - ANS✅✅meiosis
1
A place in the eukaryotic cell cycle at which a "decision" is made whether to proceed through the cell
cycle or to arrest cell cycle progression is generally known as - ANS✅✅a checkpoint
Which step of meiosis contributes to significant genetic variation? - ANS✅✅Prophase 1
In somatic cells, sister chromatids exist when - ANS✅✅exist in the G2 stage of the cell cycle
Tight pairing of homologous chromosomes during meiosis is called - ANS✅✅synapsis
a form of a gene - ANS✅✅allele
What is the probability that in an organism with a haploid number of 10, an egg will be formed that
contains all 10 chromosomes whose centromeres were derived from maternal homologs? -
ANS✅✅(1/2)^10
In each one of Mendel's dihybrid crosses, what was the common trend? - ANS✅✅the phenotypes
of the F2 generation segregated in a 9:3:3:1 ratio
In the cross (AaBb x AaBb), the genotype aabb should occur at what frequency? - ANS✅✅1/16
A 9:3:3:1 ratio of phenotypes in the F2 generation of a dihybrid cross - ANS✅✅indicates that the
dihybrid cross is basically equivalent to two independent monohybrid crosses
, Albinism in humans is inherited as a simple autosomal recessive trait. Two normal parents have five
children and one is albino. If the dominant and recessive allels for albinism are designated as "A" and
"a" respectively, then the genotypes of the parents are most likely: - ANS✅✅Mom: Aa Dad: Aa
A tall, violet plant is crossed with a dwarf, white plant and all of the F1 offspring are tall,violet. The
F1 plants are selfed to produce the F2 generation. What fraction of the F2 generation would you
expect to be dwarf, violet? - ANS✅✅3/16
How many different types of gametes can be formed by an individual of the following genotype:
AaBbCcDdEEFF? - ANS✅✅2^4=16
Consider three independently assorting genes A,B, and C. What is the probability of obtaining an
offspring that is AaBBCc from parents that are AABbCc and AaBbCc? - ANS✅✅1/16
A woman and a man are both heterozygous for freckles, which is the dominant condition. If they
have one child, what are the chances that it will have freckles? - ANS✅✅75%
With incomplete dominance, a .likely F2 phenotypic ratio in a monohybrid cross would be -
ANS✅✅1:2:1
involves heterozygotes displaying a blending of phenotypes - ANS✅✅Incomplete dominance
A condition in which one gene influences the expression of another gene is called -
ANS✅✅Epistasis
If a child is blood type A and the mother is blood type A, what is the blood type of the father? -
ANS✅✅Can't tell
Suppose an allele, b, of a sex-linked gene is recessive and embryonic lethal. A man marries a woman
who is heterozygous for this gene. If this couple had a large number of children, what would be the
predicted ratio of male children to female children? - ANS✅✅1:2
A given genotype that produces a different phenotype in males versus females - ANS✅✅Sex-
influenced inheritance
When two genes fail to assort independently, the term normally applied is - ANS✅✅linkage
