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BIOL 207: Molecular Genetics and Heredity | 100-Question Master Prep
University of Alberta (UofA) Edition
Module 1: Mendelian Genetics & Extension of Ratios
1. In a monohybrid cross between two heterozygous (Aa) individuals, what is the
expected genotypic ratio?
A) 3:1
B) 1:2:1
C) 9:3:3:1
D) 1:1 Elaboration: While the phenotypic ratio is 3:1, the genotypic ratio
accounts for 1 AA, 2 Aa, and 1 aa offspring.
2. Which law states that alleles of different genes migrate into gametes
independently of each other?
A) Law of Segregation
B) Law of Independent Assortment
C) Law of Dominance
D) Law of Linkage Elaboration: Mendel’s Second Law applies to genes
located on different chromosomes or far apart on the same chromosome.
3. A cross between a red flower and a white flower produces pink offspring. This is
an example of:
A) Codominance
B) Incomplete Dominance
C) Epistasis
D) Pleiotropy Elaboration: Incomplete dominance results in a blended
phenotype where the heterozygote is intermediate between the two
homozygotes.
4. In humans, the AB blood type is a classic example of:
A) Incomplete Dominance
B) Codominance
C) Recessive Lethality
, D) Variable Expressivity Elaboration: Both the A and B antigens are fully and
simultaneously expressed on the surface of red blood cells in
heterozygous individuals.
5. A ratio of 9:3:4 in a dihybrid cross indicates which type of interaction?
A) Dominant Epistasis
B) Recessive Epistasis
C) Complementary Gene Action
D) Redundant Gene Action Elaboration: Recessive epistasis occurs when
the recessive genotype at one locus masks the expression of alleles at a
second locus.
6. What is the phenotypic ratio of a cross between two individuals heterozygous for
a recessive lethal allele?
A) 3:1
B) 1:2:1
C) 2:1
D) 9:7 Elaboration: The homozygous recessive class (aa) dies before birth,
leaving only the AA and Aa individuals in a 1:2 ratio.
7. "Variable Expressivity" refers to:
A) Whether or not a genotype shows any phenotype.
B) The degree or intensity to which a genotype is expressed in an
individual.
C) A single gene affecting multiple traits.
D) Multiple genes affecting one trait. Elaboration: Unlike penetrance (all-or-
nothing), expressivity describes a range of phenotypic severity among
individuals with the same genotype.
8. A testcross involves crossing an individual with an unknown genotype to an
individual that is:
A) Heterozygous
B) Homozygous Dominant
C) Homozygous Recessive
, D) Hemizygous Elaboration: Crossing to a homozygous recessive ensures
that the phenotype of the offspring reveals the alleles present in the
unknown parent.
9. How many different types of gametes can be produced by an individual with the
genotype AaBbCcDd?
A) 4
B) 8
C) 16
D) 32 Elaboration: Using the formula 2n where n is the number of
heterozygous loci: 24=16.
10. In a Chi-Square test, if the calculated p-value is less than 0.05, we:
A) Accept the null hypothesis.
B) Reject the null hypothesis.
C) Conclude the data is perfect.
D) Ignore the results. Elaboration: A p<0.05 suggests the difference between
observed and expected data is statistically significant.
11. The phenomenon where one gene affects multiple, seemingly unrelated
phenotypic traits is:
A) Epistasis
B) Pleiotropy
C) Polygenic inheritance
D) Incomplete penetrance Elaboration: A classic example is sickle-cell
anemia, where a single mutation affects hemoglobin shape, blood flow, and
organ health.
12. If a 9:7 ratio is observed in the F2 generation, it indicates:
A) Recessive epistasis
B) Duplicate recessive epistasis (Complementary gene action)
C) Dominant epistasis
D) Simple dominance Elaboration: This occurs when both genes must have
at least one dominant allele to produce the phenotype.
13. Penetrance is defined as:
BIOL 207: Molecular Genetics and Heredity | 100-Question Master Prep
University of Alberta (UofA) Edition
Module 1: Mendelian Genetics & Extension of Ratios
1. In a monohybrid cross between two heterozygous (Aa) individuals, what is the
expected genotypic ratio?
A) 3:1
B) 1:2:1
C) 9:3:3:1
D) 1:1 Elaboration: While the phenotypic ratio is 3:1, the genotypic ratio
accounts for 1 AA, 2 Aa, and 1 aa offspring.
2. Which law states that alleles of different genes migrate into gametes
independently of each other?
A) Law of Segregation
B) Law of Independent Assortment
C) Law of Dominance
D) Law of Linkage Elaboration: Mendel’s Second Law applies to genes
located on different chromosomes or far apart on the same chromosome.
3. A cross between a red flower and a white flower produces pink offspring. This is
an example of:
A) Codominance
B) Incomplete Dominance
C) Epistasis
D) Pleiotropy Elaboration: Incomplete dominance results in a blended
phenotype where the heterozygote is intermediate between the two
homozygotes.
4. In humans, the AB blood type is a classic example of:
A) Incomplete Dominance
B) Codominance
C) Recessive Lethality
, D) Variable Expressivity Elaboration: Both the A and B antigens are fully and
simultaneously expressed on the surface of red blood cells in
heterozygous individuals.
5. A ratio of 9:3:4 in a dihybrid cross indicates which type of interaction?
A) Dominant Epistasis
B) Recessive Epistasis
C) Complementary Gene Action
D) Redundant Gene Action Elaboration: Recessive epistasis occurs when
the recessive genotype at one locus masks the expression of alleles at a
second locus.
6. What is the phenotypic ratio of a cross between two individuals heterozygous for
a recessive lethal allele?
A) 3:1
B) 1:2:1
C) 2:1
D) 9:7 Elaboration: The homozygous recessive class (aa) dies before birth,
leaving only the AA and Aa individuals in a 1:2 ratio.
7. "Variable Expressivity" refers to:
A) Whether or not a genotype shows any phenotype.
B) The degree or intensity to which a genotype is expressed in an
individual.
C) A single gene affecting multiple traits.
D) Multiple genes affecting one trait. Elaboration: Unlike penetrance (all-or-
nothing), expressivity describes a range of phenotypic severity among
individuals with the same genotype.
8. A testcross involves crossing an individual with an unknown genotype to an
individual that is:
A) Heterozygous
B) Homozygous Dominant
C) Homozygous Recessive
, D) Hemizygous Elaboration: Crossing to a homozygous recessive ensures
that the phenotype of the offspring reveals the alleles present in the
unknown parent.
9. How many different types of gametes can be produced by an individual with the
genotype AaBbCcDd?
A) 4
B) 8
C) 16
D) 32 Elaboration: Using the formula 2n where n is the number of
heterozygous loci: 24=16.
10. In a Chi-Square test, if the calculated p-value is less than 0.05, we:
A) Accept the null hypothesis.
B) Reject the null hypothesis.
C) Conclude the data is perfect.
D) Ignore the results. Elaboration: A p<0.05 suggests the difference between
observed and expected data is statistically significant.
11. The phenomenon where one gene affects multiple, seemingly unrelated
phenotypic traits is:
A) Epistasis
B) Pleiotropy
C) Polygenic inheritance
D) Incomplete penetrance Elaboration: A classic example is sickle-cell
anemia, where a single mutation affects hemoglobin shape, blood flow, and
organ health.
12. If a 9:7 ratio is observed in the F2 generation, it indicates:
A) Recessive epistasis
B) Duplicate recessive epistasis (Complementary gene action)
C) Dominant epistasis
D) Simple dominance Elaboration: This occurs when both genes must have
at least one dominant allele to produce the phenotype.
13. Penetrance is defined as:
