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Biology 3201
Old Public Exam Questions
August 2004 – August 2009
*Key Online
Unit 3 – Genetics
Part 1 – Mendelian Genetics
Page 2 of 19
MULTIPLE CHOICE QUESTIONS
AUGUST 2009
36. Which are alternate forms of genes?
(A) alleles
(B) chromatids
(C) hybrids
(D) sub units
37. How did Mendel obtain the F1 generation of all hybrid tall pea plants?
(A) hybrid tall Xhybrid tall
(B) hybrid tall Xpure tall
(C) pure short Xpure short
(D) pure tall Xpure short
38. Eye colour for fruit flies is determined by genes X, Y and Z. Which is illustrated if X
produces black eyes, Y produces brown eyes and Z produces magenta (purple) eyes?
(A) co-dominance
(B) incomplete dominance
(C) multiple alleles
(D) polygenic inheritance
39. Which type of inheritance causes variation in height and skin colour in humans?
(A) co-dominance
(B) incomplete dominance
(C) multiple alleles
(D) polygenic inheritance
40. What is the probability of parents having the following three children: two boys in a
row followed by a daughter?
Page 3 of 19
41. Which explains how a cross between two grey mice can produce black mice, grey
mice and white mice?
(A) Crossing over occurs between white and black alleles.
(B) Inheritance involves alleles that are incompletely dominant.
(C) Mutations occur during gamete formation.
(D) Non-disjunction results in the production of abnormal offspring.
42. What is one of Morgan’s major contributions to the field of genetics?
(A) concept of codons
(B) double helix
(C) Law of Dominance
(D) sex-linked traits
43. What does the Law of Independent Assortment state?
(A) Gene pairs always sort in the same order.
(B) Gene pairs sort randomly and independently from each other.
(C) One allele is always dominant.
(D) Sister chromatids separate during gamete formation.
44. Where does crossing over occur?
(A) anaphase of mitosis
(B) anaphase II of meiosis
(C) prophase of mitosis
(D) prophase I of meiosis
45. A baby boy inherits a recessive allele from his mother. In which circumstance would
he most likely show the trait coded for by the recessive allele?
(A) The allele is on an autosomal chromosome.
(B) The allele is on the X chromosome.
(C) The allele is on the Y chromosome.
(D) The allele undergoes a mutation.
AUGUST 2008
36. Which is the study of variation and inheritance in organisms?
(A) evolution
(B) genetics
(C) physiology
(D) zoology
Page 4 of 19
37. What is the probability of parents having three girls in a row?
38. What does the Law of Independent Assortment state?
(A) During gamete formation alleles separate.
(B) During gamete formation genes separate.
(C) The inheritance of alleles for one trait will affect the inheritance of alleles for
another trait.
(D) The inheritance of alleles for one trait will not affect the inheritance of alleles for
another trait.
39. A white bull is crossed with a red cow. All the offspring produced are roan,
containing both red and white hairs. Which describes this inheritance pattern?
(A) co-dominance
(B) incomplete dominance
(C) sex-linked inheritance
(D) polygenic inheritance
40. In the cross Rr × rr, what percentage of offspring show the recessive trait?
(A) 25 %
(B) 50 %
(C) 75 %
(D) 100 %
41. A cross was made between two black, rough-haired guinea pigs. The resulting
offspring included 6 with black rough hair and 1 with white smooth hair. Which describes
this situation?
(A) Both genes are co-dominant.
(B) Both genes are polygenic.
(C) Both parents are heterozygous.
(D) Both white and smooth are dominant traits.
42. In cattle, hornless (H) is dominant over horned (h). A hornless bull is mated with 3
cows. Cow 1 (horned) produces a horned calf, cow 2 (hornless) produces a horned calf,
and cow 3 (hornless) produces a hornless calf. Which of the cattle must have a
heterozygous genotype for this trait?
(A) bull and cow 1
(B) bull and cow 2
(C) cow 2 and calf 2
(D) cow 3 and calf 3
Page 5 of 19
43. Which describes a test cross?
(A) heterozygous × unknown
(B) homozygous × unknown
(C) recessive × unknown
(D) unknown × unknown
44. Who discovered sex-linkage?
(A) Boveri
(B) Mendel
(C) Morgan
(D) Sutton
45. A man who has type B blood and a woman who has type A blood have a child with
blood type O. What are the genotypes of the parents?
(A) I I and I I
(B) I i and I I
(C) I I and I i
(D) I i and I i
B B
B
B B
B
A A
A A
A
A
46. How did Morgan’s research with Drosophila change the understanding of Mendel’s
Law of Independent Assortment?
(A) Genes located on the same chromosome will be inherited together.
(B) Modifier genes work with other genes to control the expression of traits.
(C) Multiple genes result in continuous variation.
(D) Sex-linked genes are found on the Y chromosome.
49. What is the probability that a male will inherit a sex-linked recessive allele from his
father?
(A) 0 %
(B) 25 %
(C) 50 %
(D) 100 %
AUGUST 2007
36. Which refers to the genetic composition of an organism?
(A) allele
(B) genotype
(C) phenotype
(D) trait
37. How many different kinds of gametes can normally be produced by an organism with the
genotype RrYy?
(A) 1
(B) 2
(C) 3
(D) 4
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38. Mendel stated that units of inheritance may be inherited independently. Which best
restates this conclusion in modern terms?
(A) During fertilization, which sperm combines with which egg is a matter of chance.
(B) In mitosis, there is no difference between the original DNA molecule and its
replicated copy.
(C) In the first stage of meiosis, chromosomes pair with their homologues.
(D) In the first stage of meiosis, the segregation of one pair of chromosomes does not
affect the segregation of other chromosomes.
39. Which is a test cross?
(A) AA × Aa
(B) Aa × Aa
(C) aa × aa
(D) Aa × aa
40. A purebred red-flowered snapdragon is crossed with a purebred white-flowered
snapdragon. If all the F1 are pink what does this indicate about the alleles?
(A) Pink is dominant.
(B) Red and white are co-dominant.
(C) Red and white are incompletely dominant.
(D) Red is dominant.
41. Mr. and Mrs. Smith have blood types B and O. Four babies were tested and their blood
types are listed below. Which baby or babies could belong to Mr. and Mrs. Smith?
(A) Baby 1 only
(B) Baby 1 and Baby 4 only
(C) Baby 2 and Baby 4 only
(D) Baby 3 only
42. What is the chance that a couple will have four boys in a row?
Page 7 of 19
43. Black coat color is dominant to white coat color in guinea pigs. If a heterozygous black
guinea pig is mated with a white pig, what percentage of offspring should be black?
(A) 0 %
(B) 25 %
(C) 50 %
(D) 100 %
44. M. jalapa plants with deep crimson flowers and M. jalapa plants with yellow flowers
were studied. Cross-pollinating these plants produced plants with deep red flowers only
(F1 generation). These F1 plants were allowed to self-pollinate, and the resulting seeds
produced 450 deep red and 160 yellow M. jalapa plants. With respect to the alleles for
flower color, what do these results indicate?
(A) codominance
(B) complete dominance
(C) incomplete dominance
(D) X-linked inheritance
45. Some diseases, such as cystic fibrosis, can be inherited even if neither parent has the
disease. What is the most likely cause of this?
(A) dominant alleles
(B) environment
(C) recessive alleles
(D) weakened immune system
49. Skin color in humans is an example of what type of inheritance?
(A) incomplete dominance
(B) multiple alleles
(C) polygenic inheritance
(D) sex-linked inheritance
50. Why are human females less likely to be color-blind than males?
(A) Color blindness is linked to testosterone levels.
(B) Color blindness is the dominant condition in males.
(C) Human females have two X chromosomes.
(D) The gene for color blindness is autosomal.
51. Which scientist discovered sex-linked inheritance?
(A) Chargaff
(B) McClintock
(C) Morgan
(D) Wilkins
Page 8 of 19
52. Which describes genes carried on the same chromosome?
(A) dominant
(B) gene-linked
(C) independently assorted
(D) sex-linked
AUGUST 2006
36. Which refers to an organism with two identical alleles for a single trait?
(A) cross-fertilized
(B) heterozygous
(C) homozygous
(D) segregated
37. Who proposed the Law of Independent Assortment?
(A) Darwin
(B) Griffith
(C) Mendel
(D) Morgan
38. Which genotype(s) express a recessive trait?
(A) tt and Tt
(B) tt only
(C) TT and Tt
(D) TT only
39. What is the chance that a couple will have three girls in a row?
40. The parents of a blue-eyed man were both brown-eyed. He marries a brown-eyed woman,
whose father was brown-eyed and whose mother was blue-eyed. What are the possible
genotypes of the offspring?
(A) Bb only
(B) bb only
(C) Bb and bb
(D) BB and bb
Page 9 of 19
41. Which parental cross would produce 50% of its offspring with the recessive trait?
(A) TT × TT
(B) tt × Tt
(C) Tt × Tt
(D) tt × tt
42. In the Punnet square below, which offspring are homozygous for both traits?
(A) 1 and 6
(B) 2 and 5
(C) 3 and 8
(D) 4 and 7
43. In horses, roan coats (red and white hairs) result from codominance. If a roan male is
mated with a white female, what would be the expected phenotype ratios?
(A) all roan
(B) ½ roan, ¼ red, ¼ white
(C) ½ roan, ½ red
(D) ½ roan, ½ white
44. In snapdragon flowers, red is incompletely dominant to white. What is the phenotypic ratio
of the offspring in the F2 generation in a cross between a red flower and a white flower?
(A) all pink
(B) 3 red, 1 white
(C) 1 red, 2 pink, 1 white
(D) 1 red, 1 pink, 2 white
45. Which pattern of inheritance occurs when both alleles are fully expressed in the
phenotype of a heterozygous individual at the same time?
(A) codominance
(B) incomplete dominance
(C) polygenic inheritance
(D) sex linkage
46. Which represents a test cross?
(A) bb × bb
(B) bb × BB
(C) B_ × bb
(D) B_ × BB
Page 10 of 19
47. Which are possible blood types for the parents of a child with type AB blood?
48. Who proposed that Mendel’s factors were carried on chromosomes?
(A) Griffith
(B) Levene
(C) Morgan
(D) Sutton
49. Which type of trait is human height?
(A) complete
(B) incomplete
(C) monogenic
(D) polygenic
50. What is the probability that a male inherits his Y chromosome from his father?
(A) 0
(B) 0.25
(C) 0.50
(D) 1.0
51. Who proposed the double helix model of DNA?
(A) Franklin and Wilkins
(B) Hershey and Chase
(C) Sutton and Boveri
(D) Watson and Crick
AUGUST 2005
36. Which branch of biology deals with the principles of variation and inheritance?
(A) embryology
(B) genetics
(C) neurology
(D) zoology
37. What is the genetic make-up of an organism?
(A) allele
(B) genotype
(C) hybrid
(D) phenotype
Page 11 of 19
38. What is the chance of a family having five boys in a row?
(A) 1/2
(B) 1/16
(C) 1/32
(D) 1/64
39. If tallness is a dominant trait of pea plants, which most likely describes two pea plants
that produce 146 tall and 52 short plants when mated?
(A) both heterozygous tall
(B) both homozygous short
(C) heterozygous tall and homozygous short
(D) heterozygous tall and homozygous tall
40. Which is most likely the ratio resulting from a monohybrid cross with codominance if
both parents are hybrid?
(A) 1:1:1:1
(B) 1:2:1
(C) 2:2
(D) 3:1
41. Using the diagram below, what is the chance that individual X will be blood type AB?
(A) 0%
(B) 25%
(C) 50%
(D) 100%
42. Horned trait in cattle is dominant (H) and hornless trait is recessive (h). If a horned bull is
mated to the two cows described below, what are possible genotypes for the bull and
cows?
44. Which is a result of blending two traits from different alleles?
(A) codominance
(B) crossing over
(C) incomplete dominance
(D) sex linkage
Page 12 of 19
45. If a sex-linked trait affects more males than females, which conclusion should be drawn
about the trait?
(A) codominant
(B) incompletely dominant
(C) X-linked dominant
(D) X-linked recessive
46. Which scientist first developed the concept of “jumping genes”?
(A) Griffith
(B) Levene
(C) McClintock
(D) Mendel
55. Eye color is a sex-linked trait in fruit flies. If red eyes are dominant and white eyes are
recessive, which cross could produce red eyed males and white eyed females?
(A) heterozygous red eyed females × white-eyed males
(B) heterozygous white eyed females × red-eyed males
(C) homozygous red eyed females × red-eyed males
(D) homozygous white eyed females × white-eyed males
56. Why is the human population on the island of Newfoundland suitable for studying human
genetics?
(A) More hybrid traits are present in the population.
(B) The founder effect is preserved.
(C) The population represents a small sample size.
(D) There is great genetic diversity.
57. Which organisms did Mendel use in studying genetics?
(A) fruit flies
(B) humans
(C) monkeys
(D) pea plants
59. What is the phenotypic ratio of the offspring produced from a dihybrid cross between two
heterozygous individuals?
(A) 1:1:1:1
(B) 1:2:2:1
(C) 9:2:3:2
(D) 9:3:3:1
AUGUST 2004
36. Which is the science of heredity?
(A) evolution
(B) genetics
(C) inheritance
(D) karyotyping
Page 13 of 19
37. Which refers to the trait expressed in a heterozygous individual?
(A) allele
(B) chromosome
(C) dominant
(D) recessive
38. Who discovered fundamental principles of genetics by breeding garden peas?
(A) Darwin
(B) Margulis
(C) Mendel
(D) Watson
39. If a sex-linked trait affects more males than females, which conclusion can be made about
the trait?
(A) incompletely dominant
(B) incompletely recessive
(C) X-linked dominant
(D) X-linked recessive
40. In which field did Rosalind Franklin conduct her research?
(A) DNA fingerprinting
(B) gel electrophoresis
(C) gene cloning
(D) X-ray crystallography
41. Which refers to an organism with two different alleles for a single trait?
(A) cross-fertilized
(B) heterozygous
(C) homozygous
(D) segregated
42. Which refers to the physical appearance of an organism?
(A) genetic drift
(B) genetic heritage
(C) genotype
(D) phenotype
43. Which chromosome mutation results when a part of one chromosome changes places with
another part of the same chromosome?
(A) deletion
(B) duplication
(C) inversion
(D) translocation
Page 14 of 19
44. Which illustrates genetic relationships among a group of individuals?
(A) karyotype
(B) gene map
(C) pedigree
(D) punnett square
45. Which best describes the two individuals involved in a test cross?
(A) Both are homozygous dominant.
(B) Both are homozygous recessive.
(C) One has an unknown genotype and one is homozygous dominant.
(D) One has an unknown genotype and one is homozygous recessive.
48. Which process results in a phenotype determined by the additive effects of two or more
genes?
(A) codominance
(B) incomplete dominance
(C) polygenic inheritance
(D) sex linkage
51. In pea plants, tall is dominant over short and purple flowers are dominant over white. 500
offspring were produced from a cross between two pea plants that are both heterozygous
for each trait. Approximately, how many of the offspring would be tall with purple flowers?
(A) 30
(B) 90
(C) 280
(D) 500
56. How many different genotypes would occur in the offspring of a cross between a
homozygous individual and a heterozygous individual?
(A) 1
(B) 2
(C) 3
(D) 4
57. In horses, roan coats (red and white hairs) result from codominance. If two roan coat horses
are crossed, what would be the expected phenotype ratios?
(A) all roan
(B) ½rroan, ¼ red, ¼ white
(C) ½ roan, ½ red
(D) ½rroan, ½ white
58. What is the likelihood that a couple’s first child will be a female and second child is a male?
(A) 12.5%
(B) 25%
(C) 50%
(D) 75%
Page 15 of 19
59. Which are possible blood types for the parents of a child with AB blood?
SHORT ANSWER QUESTIONS
AUGUST 2009
78.(a) In humans, hemophilia is a sex-linked trait where normal clotting (H) is dominant
and hemophilia (h) is recessive. Tongue rolling (T) is dominant to non-rolling (t).
A non-hemophiliac male and a hemophiliac female produce a child. Both the male
and the female are heterozygous for tongue rolling. What is the probability of this
child being a hemophiliac who is a tongue roller?
Page 16 of 19
AUGUST 2008
78.(a) The gene for red/green colour blindness is a recessive sex-linked trait. The gene
for eye colour is not sex-linked. Brown eyes are dominant to blue eyes. A blue-eyed
man with normal colour vision marries a woman homozygous for brown eyes and who is
a carrier for colour blindness. Use a Punnett square to determine the genotypic ratios
for their expected offspring.
AUGUST 2007
78.(a) In corn plants, thick husk (T) is completely dominant to thin husk (t), and green
seed (G) is completely dominant to yellow seed (g). Two thick husk green seed
plants are crossed and one of the plants produced is thin husk and yellow. What
percentage of the offspring share the same genotype as the parents? What is the
phenotypic ratio of the plants produced? Show all workings.
Page 17 of 19
AUGUST 2006
78.(a) In humans, normal color vision (R) is dominant to color blindness (r). This is a
sex-linked trait (X-linked). Brown eye color (B) is dominant to blue eye color (b).
If a color blind, heterozygous brown-eyed female mated with a normal, blue-eyed
male, what percentage of the offspring would be color blind, blue-eyed males? Show your
workings.
AUGUST 2005
78.(a) In pea plants, green colour is dominant to yellow. Describe a cross that could be
used to determine if a green pea plant is homozygous dominant.
(c) In pea plants, spherical seed shape (S) is dominant to dented seed shape (s) and
yellow seeds (Y) are dominant to green seeds (y). If two pea plants, each
heterozygous for both traits, are crossed, what is the probability of the offspring
having dented, yellow seeds? Show workings.
Page 18 of 19
AUGUST 2004
78.(b) In a certain plant, red flowers (R) are dominant to white (r) and long stems (L) are
dominant to short (�). What is the expected phenotypic ratios of the offspring
resulting from a cross between a plant heterozygous for both traits with a plant that
has heterozygous red flowers and short stems? Show all workings.
Page 19 of 19