BIOL180 Lesson 6 Quiz Mendelian
Genetics Questions And Correct
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Rationales 2026 Q&A | Instant
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1. Which statement best describes Mendel's law of segregation?
A. Alleles for different genes always remain together during meiosis.
B. Dominant alleles are always expressed in every generation.
C. The two alleles for a gene separate during gamete formation.
D. Genes are exchanged between homologous chromosomes during
mitosis.
Answer: C. The two alleles for a gene separate during gamete
formation.
Rationale: The law of segregation states that an individual possesses
two alleles for a gene, but these alleles separate during gamete
formation so that each gamete receives only one allele. Fertilization
restores the pair of alleles. This principle is fundamental to Mendelian
inheritance.
2. Which organism did Gregor Mendel primarily use in his genetic
experiments?
A. Garden pea
B. Fruit fly
C. Corn
D. Mouse
,Answer: A. Garden pea
Rationale: Mendel used garden pea plants because they have easily
distinguishable traits, relatively short generation times, and can
undergo controlled self-pollination or cross-pollination. These
characteristics allowed him to study inheritance systematically.
3. What is an allele?
A. A complete chromosome
B. A protein produced by a gene
C. A pair of homologous chromosomes
D. An alternative form of a gene
Answer: D. An alternative form of a gene
Rationale: Alleles are different versions of the same gene. For
example, a gene influencing seed color may have a dominant allele
and a recessive allele. Alleles occupy corresponding positions, or loci,
on homologous chromosomes.
4. An organism with two identical alleles for a particular gene is
described as:
A. Heterozygous
B. Homozygous
C. Hemizygous
D. Polygenic
Answer: B. Homozygous
Rationale: A homozygous organism has two identical alleles at a
particular locus, such as AA or aa. A heterozygous organism has two
different alleles, such as Aa.
5. Which genotype represents a heterozygous individual?
,A. AA
B. aa
C. Aa
D. XX
Answer: C. Aa
Rationale: A heterozygous genotype contains two different alleles. In
the genotype Aa, one allele is A and the other is a, making the
individual heterozygous at that locus.
6. What is the physical appearance or observable characteristic
associated with a genotype called?
A. Phenotype
B. Genotype
C. Allele
D. Locus
Answer: A. Phenotype
Rationale: The phenotype is the observable expression of genetic and
environmental influences. Examples include flower color, seed shape,
height, or blood type. The genotype refers specifically to the genetic
makeup underlying a trait.
7. Which genotype is homozygous recessive?
A. AA
B. Aa
C. A_
D. aa
Answer: D. aa
, Rationale: A homozygous recessive genotype contains two copies of the
recessive allele. The notation aa indicates that both homologous
chromosomes carry the recessive allele.
8. If a dominant allele is represented by T and the recessive allele by
t, which genotype would produce the dominant phenotype?
A. tt only
B. TT or Tt
C. tt or Tt
D. TT only
Answer: B. TT or Tt
Rationale: Under complete dominance, an individual displays the
dominant phenotype when at least one dominant allele is present.
Therefore, both TT and Tt produce the dominant phenotype, whereas
tt produces the recessive phenotype.
9. What does a Punnett square primarily help predict?
A. The exact DNA sequence of offspring
B. The number of chromosomes in an organism
C. Possible genetic combinations in offspring
D. The environmental effects on offspring
Answer: C. Possible genetic combinations in offspring
Rationale: A Punnett square organizes parental gametes to predict
possible offspring genotypes and, when dominance relationships are
known, expected phenotypes. It does not predict the exact outcome for
every individual offspring.
10. In a monohybrid cross between two heterozygous
individuals, Aa × Aa, what is the expected genotypic ratio?
Genetics Questions And Correct
Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. Which statement best describes Mendel's law of segregation?
A. Alleles for different genes always remain together during meiosis.
B. Dominant alleles are always expressed in every generation.
C. The two alleles for a gene separate during gamete formation.
D. Genes are exchanged between homologous chromosomes during
mitosis.
Answer: C. The two alleles for a gene separate during gamete
formation.
Rationale: The law of segregation states that an individual possesses
two alleles for a gene, but these alleles separate during gamete
formation so that each gamete receives only one allele. Fertilization
restores the pair of alleles. This principle is fundamental to Mendelian
inheritance.
2. Which organism did Gregor Mendel primarily use in his genetic
experiments?
A. Garden pea
B. Fruit fly
C. Corn
D. Mouse
,Answer: A. Garden pea
Rationale: Mendel used garden pea plants because they have easily
distinguishable traits, relatively short generation times, and can
undergo controlled self-pollination or cross-pollination. These
characteristics allowed him to study inheritance systematically.
3. What is an allele?
A. A complete chromosome
B. A protein produced by a gene
C. A pair of homologous chromosomes
D. An alternative form of a gene
Answer: D. An alternative form of a gene
Rationale: Alleles are different versions of the same gene. For
example, a gene influencing seed color may have a dominant allele
and a recessive allele. Alleles occupy corresponding positions, or loci,
on homologous chromosomes.
4. An organism with two identical alleles for a particular gene is
described as:
A. Heterozygous
B. Homozygous
C. Hemizygous
D. Polygenic
Answer: B. Homozygous
Rationale: A homozygous organism has two identical alleles at a
particular locus, such as AA or aa. A heterozygous organism has two
different alleles, such as Aa.
5. Which genotype represents a heterozygous individual?
,A. AA
B. aa
C. Aa
D. XX
Answer: C. Aa
Rationale: A heterozygous genotype contains two different alleles. In
the genotype Aa, one allele is A and the other is a, making the
individual heterozygous at that locus.
6. What is the physical appearance or observable characteristic
associated with a genotype called?
A. Phenotype
B. Genotype
C. Allele
D. Locus
Answer: A. Phenotype
Rationale: The phenotype is the observable expression of genetic and
environmental influences. Examples include flower color, seed shape,
height, or blood type. The genotype refers specifically to the genetic
makeup underlying a trait.
7. Which genotype is homozygous recessive?
A. AA
B. Aa
C. A_
D. aa
Answer: D. aa
, Rationale: A homozygous recessive genotype contains two copies of the
recessive allele. The notation aa indicates that both homologous
chromosomes carry the recessive allele.
8. If a dominant allele is represented by T and the recessive allele by
t, which genotype would produce the dominant phenotype?
A. tt only
B. TT or Tt
C. tt or Tt
D. TT only
Answer: B. TT or Tt
Rationale: Under complete dominance, an individual displays the
dominant phenotype when at least one dominant allele is present.
Therefore, both TT and Tt produce the dominant phenotype, whereas
tt produces the recessive phenotype.
9. What does a Punnett square primarily help predict?
A. The exact DNA sequence of offspring
B. The number of chromosomes in an organism
C. Possible genetic combinations in offspring
D. The environmental effects on offspring
Answer: C. Possible genetic combinations in offspring
Rationale: A Punnett square organizes parental gametes to predict
possible offspring genotypes and, when dominance relationships are
known, expected phenotypes. It does not predict the exact outcome for
every individual offspring.
10. In a monohybrid cross between two heterozygous
individuals, Aa × Aa, what is the expected genotypic ratio?
