Worksheet: Alleles

In this worksheet, we will practice defining and explaining the key terms in genetics.

Q1:

In labradors, the allele for black fur is dominant to the allele for yellow fur. Which of the following best explains what dominant means?

  • AA dominant allele will only be expressed in the phenotype if two copies of it are present.
  • BIf a dominant allele is present, it will never be expressed in the phenotype.
  • CIf a dominant allele is present, it will blend with the recessive allele.
  • DIf a dominant allele is present, it will always be expressed in the phenotype.

Q2:

In humans, the allele for attached earlobes is recessive to the allele for unattached earlobes. Which of the following best describes what recessive means?

  • AA recessive allele will never be expressed in the phenotype.
  • BA recessive allele will only be expressed in the phenotype if one copy of it is present.
  • CA recessive allele will always be expressed in the phenotype.
  • DA recessive allele will only be expressed in the phenotype if two copies of it are present.

Q3:

Each human body cell has two copies of each chromosome. How many alleles will each gene have in a human body cell?

Q4:

A pea plant has two different alleles for flower color (Pp). Which of the following terms can be correctly applied to this plant?

  • AHomozygous dominant
  • BHeterozygous
  • CCodominant
  • DHomozygous recessive

Q5:

What term is used to describe an organism that has different alleles for a particular gene?

  • AHeterozygous
  • BConflicting
  • CHomozygous
  • DRecessive
  • EDominant

Q6:

What is a chromosome?

  • AAll of the DNA within an organism
  • BA threadlike structure of DNA that contains genes
  • CA section of DNA that codes for a protein
  • DA long section of amino acids that contains proteins
  • EThe physical appearance of an organism

Q7:

Which of the following best describes the meaning of alleles being codominant?

  • AIf a person is homozygous for these alleles, both are expressed in the phenotype.
  • BIf a person is homozygous for these alleles, they interact and block each other.
  • CIf a person is heterozygous for these alleles, both are expressed in the phenotype.
  • DIf a person is heterozygous for these alleles, neither are expressed in the phenotype.

Q8:

In cats, short hair is dominant to long hair.

What is the correct phenotype for the genotype Ff?

  • AShort hair
  • BMedium length hair
  • CLong hair

What is the correct phenotype for the genotype ff?

  • AMedium length hair
  • BShort hair
  • CLong hair

What is the correct phenotype for the genotype FF?

  • AMedium length hair
  • BLong hair
  • CShort hair

Q9:

In humans, having freckles is dominant to not having freckles. For the following genotypes given, state the correct phenotype.

Ff

  • AFreckles
  • BNo freckles

FF

  • AFreckles
  • BNo freckles

ff

  • AFreckles
  • BNo freckles

Q10:

What term is used to describe an organism that has the same alleles for a particular gene?

  • ARecessive
  • BDominant
  • CHeterozygous
  • DMatching
  • EHomozygous

Q11:

What is a phenotype?

  • AThe mental well-being of a person
  • BAll the DNA within an organism
  • CAll the alleles within an organism
  • DThe physical appearance of an organism
  • EThe personality of an organism

Q12:

A pea plant has the following two alleles (PP) for purple flowers. Which of the following terms can be used to describe this pea plant?

  • AHomozygous dominant
  • BHeterozygous recessive
  • CHomozygous recessive
  • DHeterozygous dominant

Q13:

What is a genotype?

  • AThe characteristics an organism develops throughout its lifetime
  • BDiseases that are inherited from parents
  • CThe physical appearance of an organism
  • DAll of the alleles present in an organism
  • EAll of the DNA within an organism

Q14:

What are alleles?

  • ASimilar forms of the same gene
  • BDifferent forms of the same protein
  • CDifferent forms of different genes
  • DDifferent forms of the same gene
  • ESame forms of different genes

Q15:

What is a genome?

  • AAll the alleles within an organism
  • BA gene that will always be expressed
  • CAll the noncoding DNA within an organism
  • DAll the DNA within an organism
  • EDifferent forms of the same gene

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