BIO 1404 Test 4 Questions with Correct Answers Latest Update 2025
An allele masked or hidden by the presence of another is referred to as: - Answers recessive
When two individuals who are heterozygous for a trait mate, what is the probability that their
offspring will exhibit the dominant trait? - Answers 75%
For the results of Mendel's dihybrid cross to be a 9:3:3:1 ratio of traits, what must the
relationship of each gene pair be? - Answers The genes must be on separate chromosomes.
When Mendel crossed two "true-breeding" pea plants with contrasting traits (e.g., tall versus
short), why did all the plants from the first (F1) generation only show one of the traits? -
Answers All of the F1 generation was heterozygous for the trait.
Mendel showed that only one of two factors (genes) associated with a trait is present in
gametes. This is known as the: - Answers law of segregation
Mendel's Law of Segregation has which of the following relationships to the concept of
homologous chromosomes? - Answers One set of homologous contain one version of all the
genes.
The two forms of genes found in the same location on the homologous chromosomes are
called: - Answers alleles
Explain the observation that recessive diseases often "skip a generation"? - Answers Recessive
alleles are not expressed in heterozygotes.
Which enzyme is responsible for new DNA synthesis? - Answers DNA polymerase
Which of the following happens first in DNA replication? - Answers The strands unwind.
Which of the following strands of DNA is(are) copied during DNA replication - Answers both the
5' to 3' and the 3' to 5' strands
In which direction does DNA polymerase add new nucleotides? - Answers 5' to 3'
How would you determine if a human cell came from a genetic female? - Answers Look for the
presence of a Barr body.
The phenotype of women with more than one X chromosome is relatively normal compared to
other trisomies? Why? - Answers They can simply form two Barr bodies, leaving them with one
active X chromosome.
Which of the following proteins ensures that separated DNA strands don't anneal back together?
- Answers single-stranded binding proteins
What is the area of DNA where DNA replication begins called? - Answers origin of replication
, Mendel performed hybridizations by transferring pollen from the _______ of the male plant to the
female ova. - Answers anther
Which is one of the seven characteristics that Mendel observed in pea plants? - Answers seed
texture
Imagine you are performing a cross involving seed color in garden pea plants. What F1 offspring
would you expect if you cross true-breeding parents with green seeds and yellow seeds? Yellow
seed color is dominant over green. - Answers 100 percent yellow seeds
Consider a cross to investigate the pea pod texture trait, involving constricted or inflated pods.
Mendel found that the traits behave according to a dominant/recessive pattern in which inflated
pods were dominant. If you performed this cross and obtained 650 inflated-pod plants in the F2
generation, approximately how many constricted-pod plants would you expect to have? -
Answers 217
A scientist pollinates a true-breeding pea plant with violet, terminal flowers with pollen from a
true-breeding pea plant with white, axial flowers. Which of the following observations would
most accurately describe the F2 generation? - Answers 75% violet flowers; 75% axial flowers
The observable traits expressed by an organism are described as its ________. - Answers
phenotype
A recessive trait will be observed in individuals that are ________ for that trait. - Answers
homozygous
If black and white true-breeding mice are mated and the result is all gray offspring, what
inheritance pattern would this be indicative of? - Answers incomplete dominance
The ABO blood groups in humans are expressed as the IA, IB, and i alleles. The IA allele encodes
the A blood group antigen, IB encodes B, and i encodes O. Both A and B are dominant to O. If a
heterozygous blood type A parent (IAi) and a heterozygous blood type B parent (IBi) mate, one
quarter of their offspring will have AB blood type (IAIB) in which both antigens are expressed
equally. Therefore, ABO blood groups are an example of: - Answers multiple alleles and
codominance
In a mating between two individuals that are heterozygous for a recessive lethal allele that is
expressed in utero, what genotypic ratio (homozygous dominant:heterozygous:homozygous
recessive) would you expect to observe in the offspring? - Answers 1:2:0
If the allele encoding polydactyly (six fingers) is dominant why do most people have five fingers?
- Answers The polydactyl allele is very rare in the human population.
A farmer raises black and white chickens. To his surprise, when the first generation of eggs
hatch all the chickens are black with white speckles throughout their feathers. What should the
An allele masked or hidden by the presence of another is referred to as: - Answers recessive
When two individuals who are heterozygous for a trait mate, what is the probability that their
offspring will exhibit the dominant trait? - Answers 75%
For the results of Mendel's dihybrid cross to be a 9:3:3:1 ratio of traits, what must the
relationship of each gene pair be? - Answers The genes must be on separate chromosomes.
When Mendel crossed two "true-breeding" pea plants with contrasting traits (e.g., tall versus
short), why did all the plants from the first (F1) generation only show one of the traits? -
Answers All of the F1 generation was heterozygous for the trait.
Mendel showed that only one of two factors (genes) associated with a trait is present in
gametes. This is known as the: - Answers law of segregation
Mendel's Law of Segregation has which of the following relationships to the concept of
homologous chromosomes? - Answers One set of homologous contain one version of all the
genes.
The two forms of genes found in the same location on the homologous chromosomes are
called: - Answers alleles
Explain the observation that recessive diseases often "skip a generation"? - Answers Recessive
alleles are not expressed in heterozygotes.
Which enzyme is responsible for new DNA synthesis? - Answers DNA polymerase
Which of the following happens first in DNA replication? - Answers The strands unwind.
Which of the following strands of DNA is(are) copied during DNA replication - Answers both the
5' to 3' and the 3' to 5' strands
In which direction does DNA polymerase add new nucleotides? - Answers 5' to 3'
How would you determine if a human cell came from a genetic female? - Answers Look for the
presence of a Barr body.
The phenotype of women with more than one X chromosome is relatively normal compared to
other trisomies? Why? - Answers They can simply form two Barr bodies, leaving them with one
active X chromosome.
Which of the following proteins ensures that separated DNA strands don't anneal back together?
- Answers single-stranded binding proteins
What is the area of DNA where DNA replication begins called? - Answers origin of replication
, Mendel performed hybridizations by transferring pollen from the _______ of the male plant to the
female ova. - Answers anther
Which is one of the seven characteristics that Mendel observed in pea plants? - Answers seed
texture
Imagine you are performing a cross involving seed color in garden pea plants. What F1 offspring
would you expect if you cross true-breeding parents with green seeds and yellow seeds? Yellow
seed color is dominant over green. - Answers 100 percent yellow seeds
Consider a cross to investigate the pea pod texture trait, involving constricted or inflated pods.
Mendel found that the traits behave according to a dominant/recessive pattern in which inflated
pods were dominant. If you performed this cross and obtained 650 inflated-pod plants in the F2
generation, approximately how many constricted-pod plants would you expect to have? -
Answers 217
A scientist pollinates a true-breeding pea plant with violet, terminal flowers with pollen from a
true-breeding pea plant with white, axial flowers. Which of the following observations would
most accurately describe the F2 generation? - Answers 75% violet flowers; 75% axial flowers
The observable traits expressed by an organism are described as its ________. - Answers
phenotype
A recessive trait will be observed in individuals that are ________ for that trait. - Answers
homozygous
If black and white true-breeding mice are mated and the result is all gray offspring, what
inheritance pattern would this be indicative of? - Answers incomplete dominance
The ABO blood groups in humans are expressed as the IA, IB, and i alleles. The IA allele encodes
the A blood group antigen, IB encodes B, and i encodes O. Both A and B are dominant to O. If a
heterozygous blood type A parent (IAi) and a heterozygous blood type B parent (IBi) mate, one
quarter of their offspring will have AB blood type (IAIB) in which both antigens are expressed
equally. Therefore, ABO blood groups are an example of: - Answers multiple alleles and
codominance
In a mating between two individuals that are heterozygous for a recessive lethal allele that is
expressed in utero, what genotypic ratio (homozygous dominant:heterozygous:homozygous
recessive) would you expect to observe in the offspring? - Answers 1:2:0
If the allele encoding polydactyly (six fingers) is dominant why do most people have five fingers?
- Answers The polydactyl allele is very rare in the human population.
A farmer raises black and white chickens. To his surprise, when the first generation of eggs
hatch all the chickens are black with white speckles throughout their feathers. What should the
