BIOL180 Unit Test 6 Mendelian
Genetics and Inheritance Questions
And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A |
Instant Download Pdf
1. Which statement best describes an allele?
A. A complete set of chromosomes in an organism
B. A physical trait produced by an organism
C. A specific chromosome pair
D. An alternative form of a gene
Answer: D. An alternative form of a gene
Rationale: An allele is one of two or more alternative versions of a
particular gene. Different alleles can produce different forms of a
characteristic, such as different flower colors or blood types. Alleles
occupy corresponding locations, called loci, on homologous
chromosomes. An individual inherits one allele from each parent for a
typical diploid gene.
2. What is a genotype?
A. The genetic makeup of an organism for a particular trait or set of
traits
B. The observable physical appearance of an organism
C. The environmental conditions affecting an organism
D. The location of a gene on a chromosome
,Answer: A. The genetic makeup of an organism for a particular trait
or set of traits
Rationale: A genotype refers to the alleles an organism possesses. For
example, TT, Tt, and tt are different genotypes for a gene with two
alleles. The phenotype is the observable characteristic that results from
the genotype and environmental influences.
3. Which term describes the observable characteristics of an
organism?
A. Locus
B. Genotype
C. Phenotype
D. Allele
Answer: C. Phenotype
Rationale: The phenotype is the observable or measurable expression
of a trait. It can include physical characteristics, physiological
properties, or behaviors. Although phenotype is influenced by
genotype, environmental factors can also influence how a trait is
expressed.
4. An organism with two identical alleles for a particular gene is
described as:
A. Heterozygous
B. Homozygous
C. Hemizygous
D. Hybridized
Answer: B. Homozygous
,Rationale: An organism is homozygous for a gene when it carries two
identical alleles, such as AA or aa. An organism with two different
alleles, such as Aa, is heterozygous.
5. An organism with genotype Aa is:
A. Homozygous dominant
B. Homozygous recessive
C. Heterozygous
D. Polygenic
Answer: C. Heterozygous
Rationale: The genotype Aa contains two different alleles, so the
organism is heterozygous. If A is completely dominant over a, the
phenotype of a heterozygous individual will generally express the
dominant trait.
6. Which genotype represents a homozygous recessive individual?
A. AA
B. Aa
C. AABB
D. aa
Answer: D. aa
Rationale: Homozygous means that both alleles are the same, while
recessive identifies the allele that is expressed phenotypically when two
copies are present under complete dominance. Therefore, aa is
homozygous recessive.
7. Mendel's law of segregation states that:
A. Dominant alleles always separate from chromosomes
B. Genes for different traits are always inherited together
, C. The two alleles for a gene separate during gamete formation
D. Recessive alleles disappear in heterozygous organisms
Answer: C. The two alleles for a gene separate during gamete
formation
Rationale: Mendel's law of segregation explains that an individual has
two alleles for a gene, but these alleles separate during meiosis so that
each gamete receives only one allele. Fertilization restores the pair
when gametes combine.
8. Which process provides the physical basis for Mendel's law of
segregation?
A. DNA replication
B. Separation of homologous chromosomes during meiosis
C. Translation
D. Crossing over between sister chromatids only
Answer: B. Separation of homologous chromosomes during meiosis
Rationale: During meiosis, homologous chromosomes separate from
one another. Because alleles for a gene are located on homologous
chromosomes, their separation results in different gametes receiving
different alleles. This provides the cellular basis for Mendel's
segregation principle.
9. Mendel primarily studied inheritance using:
A. Fruit flies
B. Mice
C. Pea plants
D. Bacteria
Answer: C. Pea plants
Genetics and Inheritance Questions
And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A |
Instant Download Pdf
1. Which statement best describes an allele?
A. A complete set of chromosomes in an organism
B. A physical trait produced by an organism
C. A specific chromosome pair
D. An alternative form of a gene
Answer: D. An alternative form of a gene
Rationale: An allele is one of two or more alternative versions of a
particular gene. Different alleles can produce different forms of a
characteristic, such as different flower colors or blood types. Alleles
occupy corresponding locations, called loci, on homologous
chromosomes. An individual inherits one allele from each parent for a
typical diploid gene.
2. What is a genotype?
A. The genetic makeup of an organism for a particular trait or set of
traits
B. The observable physical appearance of an organism
C. The environmental conditions affecting an organism
D. The location of a gene on a chromosome
,Answer: A. The genetic makeup of an organism for a particular trait
or set of traits
Rationale: A genotype refers to the alleles an organism possesses. For
example, TT, Tt, and tt are different genotypes for a gene with two
alleles. The phenotype is the observable characteristic that results from
the genotype and environmental influences.
3. Which term describes the observable characteristics of an
organism?
A. Locus
B. Genotype
C. Phenotype
D. Allele
Answer: C. Phenotype
Rationale: The phenotype is the observable or measurable expression
of a trait. It can include physical characteristics, physiological
properties, or behaviors. Although phenotype is influenced by
genotype, environmental factors can also influence how a trait is
expressed.
4. An organism with two identical alleles for a particular gene is
described as:
A. Heterozygous
B. Homozygous
C. Hemizygous
D. Hybridized
Answer: B. Homozygous
,Rationale: An organism is homozygous for a gene when it carries two
identical alleles, such as AA or aa. An organism with two different
alleles, such as Aa, is heterozygous.
5. An organism with genotype Aa is:
A. Homozygous dominant
B. Homozygous recessive
C. Heterozygous
D. Polygenic
Answer: C. Heterozygous
Rationale: The genotype Aa contains two different alleles, so the
organism is heterozygous. If A is completely dominant over a, the
phenotype of a heterozygous individual will generally express the
dominant trait.
6. Which genotype represents a homozygous recessive individual?
A. AA
B. Aa
C. AABB
D. aa
Answer: D. aa
Rationale: Homozygous means that both alleles are the same, while
recessive identifies the allele that is expressed phenotypically when two
copies are present under complete dominance. Therefore, aa is
homozygous recessive.
7. Mendel's law of segregation states that:
A. Dominant alleles always separate from chromosomes
B. Genes for different traits are always inherited together
, C. The two alleles for a gene separate during gamete formation
D. Recessive alleles disappear in heterozygous organisms
Answer: C. The two alleles for a gene separate during gamete
formation
Rationale: Mendel's law of segregation explains that an individual has
two alleles for a gene, but these alleles separate during meiosis so that
each gamete receives only one allele. Fertilization restores the pair
when gametes combine.
8. Which process provides the physical basis for Mendel's law of
segregation?
A. DNA replication
B. Separation of homologous chromosomes during meiosis
C. Translation
D. Crossing over between sister chromatids only
Answer: B. Separation of homologous chromosomes during meiosis
Rationale: During meiosis, homologous chromosomes separate from
one another. Because alleles for a gene are located on homologous
chromosomes, their separation results in different gametes receiving
different alleles. This provides the cellular basis for Mendel's
segregation principle.
9. Mendel primarily studied inheritance using:
A. Fruit flies
B. Mice
C. Pea plants
D. Bacteria
Answer: C. Pea plants
