Fundamentals of Genetics
Hitchhiker's thumb (H) is dominant to no hitchhiker's thumb
(h). A woman who does not have hitchhiker's thumb
marries a man who is heterozygous for hitchhiker's thumb.
What is the probable genotypic ratio of their children?
0% Hh: 100% hh
50% Hh: 50% hh
75% Hh: 25% hh
100% Hh: 0% hh
Gregor Mendel developed an understanding of heredity
through his experiments with pea plants. Two pairs of
homologous chromosomes had a genotype of AaBb. All of
the following are possible allele combinations that could be
formed if this cell undergoes meiosis exceptA.
A person can have either straight or bent pinky fingers. A
woman who is homozygous for bent pinky fingers has
children with a man who has straight pinky fingers. All of
their children have bent pinky fingers. The trait for bent pinky
fingers is an example of a trait that is
D. incompletely dominant
The characteristic for curly hair (C) is
dominant to the characteristic for straight
hair (c). A cross between two individuals
for hair type is shown in the Punnett
square to the right.
What must the genotype of the parents be to produce the
results shown in the Punnett square?
A. homozygous dominant x homozygous dominant
B. homozygous dominant x heterozygous
C. homozygous recessive x homozygous dominant
D. heterozygous x heterozygous
A geneticist studying fruit flies hypothesizes that short wings are
a recessive trait coded for by a single gene. Which observation is
most likely to have led her to form this hypothesis?
Flies have wing lengths ranging from very long to very short.
Flies with long wings are less likely to survive.
Flies with long wings can produce offspring with short wings.
Flies with short wings prefer to mate with flies with long wings.
Female cattle that have white coats are crossed with male
cattle that have red coats. Both male and female offspring
have roan coats, which are coats with both red hairs and
Which of the following best describes the genetics of coat
color in the cattle?
A. The red and white alleles are sex-linked.
B. The red and white alleles are co-dominant.
C. The red allele is recessive to the white allele.
D. The red allele is dominant to the white allele.
In tomato plants, the tall vine allele (T) is dominant to the
short vine allele (t). Two tomato plants are crossed. Among
the offspring plants grown from seed, 45% have tall vines and
55% have short vines.
What are the most likely genotypes of the parent plants?
A. TT and tt
B. Tt and TT
C. Tt and tt
D. tt and tt
In canaries, the gene for singing (S) is dominant over the gene
for non-singing (s). When hybrid singing canaries are mated
with non-singing canaries, what percentage of the offspring is
likely to possess the singing trait?
Only red tulips result from a cross between homozygous red
and homozygous white tulips. This illustrates the principle
C. independent assortment.
D. incomplete dominance.
In minks, the gene for brown fur (B) is dominant over the
gene for silver fur (b). Which set of genotypes represents a
cross of two brown minks that could produce offspring with
A. Bb × Bb
B. BB × Bb
C. BB × bb
D. Bb × bb
If B represents the dominant allele for a trait, and b
represents the recessive allele, in which pair of crosses must
all of the offspring produced have the same phenotype?
A. Bb × bb and BB × Bb
B. BB × BB and Bb × Bb
C. Bb × bb and Bb × Bb
D. BB × Bb and BB × bb
Which of the following statements best explains why
offspring produced by sexual reproduction often look similar
to, but not exactly the same as, their parents?
A. The offspring have genetic material from both the
mother and the father.
B. The cells of the offspring contain all the dominant
genes from the parents.
C. The cells of the offspring undergo mitosis many
times as the offspring grow and develop.
D. The offspring have a period of embryonic
development, rather than being
In which situation could a mutation be passed on to the
offspring of an organism?
A. A cell in the uterine wall of a human female
undergoes a chromosomal alteration.
B. Ultraviolet radiation causes skin cells to undergo
uncontrolled mitotic division.
C. The DNA of a human lung cell undergoes random
D. A primary sex cell in a human forms a gamete that
contains 24 chromosomes.
Which best explains how meiosis is a contributing factor to
genetic variation within a species?
A. Meiosis reduces the number of mutations within an
B. Meiosis produces daughter cells that will contain identical
C. Meiosis results in offspring that contain alleles from only
one parent gamete.
D. Meiosis allows for crossing over of chromosomes,
resulting in new gene combinations.
A litter of guinea pigs can vary in color. Some are solid white
and some are brown and white, while others are black and
white. The color and the pattern of each guinea pig are
distinct from those of its parents and siblings. What process is
responsible for the differences seen in each guinea pig?
Which type of cell must contain a mutation in order for the
mutation to be passed from a woman to her offspring?
A. blood cell
B. brain cell
C. egg cell
D. skin cell
The diagram to the right provides information
about a carrot cell. A carrot cell contains
18 chromosomes. Which of the following
diagrams illustrates the correct number of chromosomes in new
cells produced by meiosis?
Two organisms with striped fur mate and produce four
offspring. Three of the offspring have striped fur but one has
no stripes. The non-striped coat is probably what type of
The chromosomes below are found in a cell of Purple Vetch, a
Texas wild flower. What is the maximum number of different
combinations of the alleles that could be found in gametes
produced by the flower?
The breed of chicken found
to the right is identified by
their short legs and five toes.
Based on the information in the table above, which of the
following crosses will produce 25% of its offspring with four
A. TT x TT
B. TT x Tt
C. Tt x Tt
D. tt x tt
A cross between two mice with long tails and brown fur
produced the four types of offspring listed below.
Long-tailed with brown fur
Long-tailed with white fur
Short-tailed with brown fur
Short-tailed with white fur
Which genetic mechanism best explains the results of this cross?
B. Dependent assortment
C. Gene linkage
D. Independent assortment
Meiosis is an essential part of sexual reproduction. This is
because meiosis creates sex cells that have A.
One-fourth the normal number of chromosomes
One-third the normal number of chromosomes
Three-fourths the normal number of chromosomes
One-half the normal number of chromosomes
Black fur in mice (B) is dominant to brown fur (b). Short tails
(T) is dominant to long tails (t). What proportion of the
progeny of the cross BbTt x BBtt will have black fur and long
A couple has three children, all of whom have brown eyes
and blond hair. Both parents are homozygous for brown eyes
(BB), and one is blond (rr) while the other is a redhead (Rr).
What is the probability that the next child will be a browneyed redhead?
In pea plants, the long-stem trait (L) is dominant over the
short-stem trait (l). Two pea plants were crossed and
produced seeds that yielded 165 long-stem plants and 54
short-stem plants. The genotypes of the parent plants were
most likely —
A. LL and ll.
B. Ll and LL.
C. ll and ll.
D. Ll and Ll.
The following displays a:
A. normal female
B. normal male
C. male with a mutation
D. female w a mutation
**if there is a mutation – what is it/does it cause? (be specific)
During meiosis, if chromosomes fail to separate it is
known as ______________.
When three chromosomes are present on the 21st pair it
is known as _________________.
When an individual is missing a chromosome they only
have a total of __________ chromosomes
If pair #9 was missing one it would be called
According to the gel below– who is guilty?
B. Suspect 2
C. Suspect 1 and 2
D. no one that was tested for this