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?

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

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

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 recessive
  • BHeterozygous
  • CCodominant
  • DHomozygous dominant

Q5:

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

  • AHeterozygous
  • BRecessive
  • CDominant
  • DConflicting
  • EHomozygous

Q6:

What is a chromosome?

  • AA long section of amino acids that contains proteins
  • BAll of the DNA within an organism
  • CThe physical appearance of an organism
  • DA threadlike structure of DNA that contains genes
  • EA section of DNA that codes for a protein

Q7:

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

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

Q8:

In cats, short hair is dominant to long hair.

What is the correct phenotype for the genotype Ff?

  • ALong hair
  • BShort hair
  • CMedium length 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?

  • ALong hair
  • BMedium length hair
  • CShort hair

Q9:

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

Ff

  • ANo freckles
  • BFreckles

FF

  • AFreckles
  • BNo freckles

ff

  • ANo freckles
  • BFreckles

Q10:

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

  • AHomozygous
  • BHeterozygous
  • CDominant
  • DMatching
  • ERecessive

Q11:

What is a phenotype?

  • AAll the DNA within an organism
  • BThe mental well-being of a person
  • CThe personality of an organism
  • DThe physical appearance of an organism
  • EAll the alleles within 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 dominant
  • CHeterozygous recessive
  • DHomozygous recessive

Q13:

What is a genotype?

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

Q14:

What are alleles?

  • ADifferent forms of the same gene
  • BSimilar forms of the same gene
  • CDifferent forms of different genes
  • DDifferent forms of the same protein
  • ESame forms of different genes

Q15:

What is a genome?

  • AAll the DNA within an organism
  • BAll the noncoding DNA within an organism
  • CDifferent forms of the same gene
  • DAll the alleles within an organism
  • EA gene that will always be expressed

Q16:

The diagram provided shows the basic outline of a chromosome.

What is represented by labels A and B?

  • ADifferent alleles
  • BThe same gene
  • CDifferent genes
  • DThe genotype
  • EChromosomes

What is represented by labels A and C?

  • AThe genotype
  • BThe same allele
  • CDifferent loci
  • DDifferent genes
  • EDifferent alleles

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