BIO 171 EXAM 4 COMPLETE STUDY GUIDE
WITH SOLVED QUESTIONS
◉ A gene in fruit flies has two alleles, A1 and A2. It is not known
whether A1 shows dominance (or is recessive), is codominant, or
shows incomplete dominance. A monohybrid cross is carried out
and 1/4 of the offspring have one phenotype (x) while ¼ have
another phenotype (y) and ½ have a third phenotype (z). Which of
the following is a possible hypotheses explaining this finding?
Answer: A1 and A2 show incomplete dominance
◉ you are examining a human pedigree for a trait. you notice that an
offspring can be affected even if neither parent is affected. this tells
you that the trait is...
Answer: recessive
◉ In humans, assume that the ability to roll the tongue (R) is
dominant to being unable to roll (r). Having freckles (F) is dominant
to having no freckles (f). If a woman heterozygous for both traits
married a man with no freckles who couldn't roll his tongue, what is
the probability that they would have a freckled, tongue-rolling child?
Answer: 1/4
,◉ proteins produced on ribosomes are responsible for determining
an organism's ___
Answer: phenotype
◉ which of the following represents the expected genotypes of an F1
generation consisting of 8 individuals from a cross of a true breeding
black (BB) rabbit and a true breeding white (bb) rabbit?
Answer: 0 BB, 0 bb, 8 Bb
◉ In rabbits, coat color can be black or white, and is controlled by a
single gene, gene B. Black is a dominant trait. Which of the following
genotypes corresponds to a black rabbit phenotype?
Answer: Bb, or bB, or BB
◉ what made the plant breeding studies performed by Mendel more
successful than plant breeding studies performed by others?
Answer: Mendel used statistical analysis to analyze the phenotypes
he observed
◉ Recall that alleles of a single gene will segregate from each other
during anaphase I. When do alleles for two different genes, located
on two different chromosomes, segregate?
Answer: anaphase 1
, ◉ A researcher is creating pedigrees for a trait he suspects to be
dominant in humans. What are some of the likely features of his
pedigrees for families with this trait?
Answer: not:
-only females will have this dominant trait
-All the offspring of a mating where only one parent has the trait will
themselves be affected.
-The occurrence of mating between individuals with this trait will be
high, because all dominant traits are common within any given
population.
◉ You are given two true-breeding groups of rabbits. The first group
has floppy ears and white coat color. The second group has straight
ears and black coat color. When you perform a cross of these two
groups to obtain an F1 generation, you see that all of your rabbits
have floppy ears and grey coat color. Which of the following
possibilities appears to be supported by what you see in the F1
generation?
Answer: floppy ears are dominant over straight ears; coat color is
determined by incomplete dominance
◉ genes that modify the expression of other genes show
Answer: epistasis
WITH SOLVED QUESTIONS
◉ A gene in fruit flies has two alleles, A1 and A2. It is not known
whether A1 shows dominance (or is recessive), is codominant, or
shows incomplete dominance. A monohybrid cross is carried out
and 1/4 of the offspring have one phenotype (x) while ¼ have
another phenotype (y) and ½ have a third phenotype (z). Which of
the following is a possible hypotheses explaining this finding?
Answer: A1 and A2 show incomplete dominance
◉ you are examining a human pedigree for a trait. you notice that an
offspring can be affected even if neither parent is affected. this tells
you that the trait is...
Answer: recessive
◉ In humans, assume that the ability to roll the tongue (R) is
dominant to being unable to roll (r). Having freckles (F) is dominant
to having no freckles (f). If a woman heterozygous for both traits
married a man with no freckles who couldn't roll his tongue, what is
the probability that they would have a freckled, tongue-rolling child?
Answer: 1/4
,◉ proteins produced on ribosomes are responsible for determining
an organism's ___
Answer: phenotype
◉ which of the following represents the expected genotypes of an F1
generation consisting of 8 individuals from a cross of a true breeding
black (BB) rabbit and a true breeding white (bb) rabbit?
Answer: 0 BB, 0 bb, 8 Bb
◉ In rabbits, coat color can be black or white, and is controlled by a
single gene, gene B. Black is a dominant trait. Which of the following
genotypes corresponds to a black rabbit phenotype?
Answer: Bb, or bB, or BB
◉ what made the plant breeding studies performed by Mendel more
successful than plant breeding studies performed by others?
Answer: Mendel used statistical analysis to analyze the phenotypes
he observed
◉ Recall that alleles of a single gene will segregate from each other
during anaphase I. When do alleles for two different genes, located
on two different chromosomes, segregate?
Answer: anaphase 1
, ◉ A researcher is creating pedigrees for a trait he suspects to be
dominant in humans. What are some of the likely features of his
pedigrees for families with this trait?
Answer: not:
-only females will have this dominant trait
-All the offspring of a mating where only one parent has the trait will
themselves be affected.
-The occurrence of mating between individuals with this trait will be
high, because all dominant traits are common within any given
population.
◉ You are given two true-breeding groups of rabbits. The first group
has floppy ears and white coat color. The second group has straight
ears and black coat color. When you perform a cross of these two
groups to obtain an F1 generation, you see that all of your rabbits
have floppy ears and grey coat color. Which of the following
possibilities appears to be supported by what you see in the F1
generation?
Answer: floppy ears are dominant over straight ears; coat color is
determined by incomplete dominance
◉ genes that modify the expression of other genes show
Answer: epistasis
