BIO 340 Final Exam 2026/2027 | Biology Practice Questions & Verified
Answers | Comprehensive Final Exam Review
1. The word heterozygous means that the members of the allelic pair are
recessive
the same
isometric
the phenotype
different
2. At the genetic level, biological evolution is:
natural selection.
a change in allele frequencies over time.
an increase in fitness over time.
a population change over time.
a change in fitness over time.
3. What defines a recessive allele in genetics?
An allele that is always expressed in the phenotype.
An allele that can be expressed in a heterozygous condition.
An allele that is only expressed in the phenotype when two
copies are present.
An allele that masks the expression of another allele.
4. Describe how the phenotypic ratio can be used to predict the outcome
of a genetic cross.
The phenotypic ratio helps predict the expected proportions
, of different traits in offspring based on parental genotypes.
The phenotypic ratio determines the survival rate of offspring.
The phenotypic ratio indicates the number of alleles present in a
population.
The phenotypic ratio is used to measure genetic diversity.
5. Alleles are defined as:
genes that resemble colored marbles in a hat
slightly different forms of the same gene
genes found only in germ cells
genes that are always found in sets of two
genes found only in somatic cells
6. What is the definition of a dominant allele?
An allele that expresses its trait even in the presence of a
recessive allele.
An allele that does not affect the phenotype when a dominant
allele is present.
An allele that is always expressed regardless of other alleles.
An allele that only expresses its trait when paired with another
dominant allele.
7. What defines polygenic traits in genetics?
Traits determined by a single gene.
Traits that are always dominant.
Traits controlled by multiple genes.
Traits influenced by environmental factors.
,8. In a genetic study, researchers find that a mutation in a single gene
affects both the color and size of a flower. What genetic concept does
this scenario illustrate?
Polygenic inheritance
Epistasis
Mendelian inheritance
Pleiotropy
9. Describe the implications of having a recessive lethal allele in a
population.
Recessive lethal alleles have no impact on population dynamics.
Recessive lethal alleles are beneficial for population growth.
Recessive lethal alleles can reduce the population size by
causing death in homozygous individuals, affecting allele
frequencies.
Recessive lethal alleles only affect the phenotype of
heterozygous individuals.
10. What is the primary purpose of a pedigree in genetics?
To determine allele frequencies in a population
To track inheritance patterns across generations
To analyze chromosome structure
To identify dominant and recessive traits
11. Evolution in a population genetics sense is:
Gradual improvements with time
A change in allele frequencies through time.
, Natural Selection
Survival of the fittest.
The tendency of species to perfect themselves
12. A recessive allele is
genetic variance at a single locus attributable to dominance of
one allele over another
an allele that expresses its phenotypic effect even when it is
present with a dominant allele
an allele whose phenotypic effect is not expressed in a
heterozygote
the result of two crossovers occurring in a chromosomal region
under study
a change in allelic frequency due to sampling error
13. What does heterozygous mean?
the different forms of a trait (hair color--> brown, blonde, red
When neither gene is fully dominant; offspring is a mixture of
both
An organism that has the same genes for a trait (TT or tt)
An organism that has different genes for a trait (Tt)
14. Describe the significance of being heterozygous in the context of
Mendelian inheritance.
Being heterozygous has no impact on Mendelian inheritance.
Being heterozygous results in the formation of polygenic traits.
Being heterozygous means that both alleles are recessive,
Answers | Comprehensive Final Exam Review
1. The word heterozygous means that the members of the allelic pair are
recessive
the same
isometric
the phenotype
different
2. At the genetic level, biological evolution is:
natural selection.
a change in allele frequencies over time.
an increase in fitness over time.
a population change over time.
a change in fitness over time.
3. What defines a recessive allele in genetics?
An allele that is always expressed in the phenotype.
An allele that can be expressed in a heterozygous condition.
An allele that is only expressed in the phenotype when two
copies are present.
An allele that masks the expression of another allele.
4. Describe how the phenotypic ratio can be used to predict the outcome
of a genetic cross.
The phenotypic ratio helps predict the expected proportions
, of different traits in offspring based on parental genotypes.
The phenotypic ratio determines the survival rate of offspring.
The phenotypic ratio indicates the number of alleles present in a
population.
The phenotypic ratio is used to measure genetic diversity.
5. Alleles are defined as:
genes that resemble colored marbles in a hat
slightly different forms of the same gene
genes found only in germ cells
genes that are always found in sets of two
genes found only in somatic cells
6. What is the definition of a dominant allele?
An allele that expresses its trait even in the presence of a
recessive allele.
An allele that does not affect the phenotype when a dominant
allele is present.
An allele that is always expressed regardless of other alleles.
An allele that only expresses its trait when paired with another
dominant allele.
7. What defines polygenic traits in genetics?
Traits determined by a single gene.
Traits that are always dominant.
Traits controlled by multiple genes.
Traits influenced by environmental factors.
,8. In a genetic study, researchers find that a mutation in a single gene
affects both the color and size of a flower. What genetic concept does
this scenario illustrate?
Polygenic inheritance
Epistasis
Mendelian inheritance
Pleiotropy
9. Describe the implications of having a recessive lethal allele in a
population.
Recessive lethal alleles have no impact on population dynamics.
Recessive lethal alleles are beneficial for population growth.
Recessive lethal alleles can reduce the population size by
causing death in homozygous individuals, affecting allele
frequencies.
Recessive lethal alleles only affect the phenotype of
heterozygous individuals.
10. What is the primary purpose of a pedigree in genetics?
To determine allele frequencies in a population
To track inheritance patterns across generations
To analyze chromosome structure
To identify dominant and recessive traits
11. Evolution in a population genetics sense is:
Gradual improvements with time
A change in allele frequencies through time.
, Natural Selection
Survival of the fittest.
The tendency of species to perfect themselves
12. A recessive allele is
genetic variance at a single locus attributable to dominance of
one allele over another
an allele that expresses its phenotypic effect even when it is
present with a dominant allele
an allele whose phenotypic effect is not expressed in a
heterozygote
the result of two crossovers occurring in a chromosomal region
under study
a change in allelic frequency due to sampling error
13. What does heterozygous mean?
the different forms of a trait (hair color--> brown, blonde, red
When neither gene is fully dominant; offspring is a mixture of
both
An organism that has the same genes for a trait (TT or tt)
An organism that has different genes for a trait (Tt)
14. Describe the significance of being heterozygous in the context of
Mendelian inheritance.
Being heterozygous has no impact on Mendelian inheritance.
Being heterozygous results in the formation of polygenic traits.
Being heterozygous means that both alleles are recessive,
