Genetics Quiz

Which of the following best describes a dominant allele?

• An allele that is only expressed when paired with another dominant allele

• An allele that is masked by a recessive allele

• An allele that is always expressed when present

• An allele that causes a mutation in the DNA

What does it mean if an organism is homozygous for a trait?

• It has two different alleles for a trait

• It has one dominant and one recessive allele

• It has two identical alleles for a trait

• It has no alleles for that trait

A heterozygous genotype consists of:

• Two dominant alleles

• Two recessive alleles

• One dominant and one recessive allele

• No alleles at all

Which of the following is an example of a phenotype?

• Bb

• Blue eyes

• Homozygous

• Genotype

What is the term for the genetic makeup of an organism?

• Phenotype

• Trait

• Genotype

• Allele

If a trait is recessive, it will be expressed only when:

• At least one dominant allele is present

• Two dominant alleles are present

• Two recessive alleles are present

• The organism is heterozygous

​ (a)   alleles are always expressed when they are present.

​ (b)   alleles are only expressed when the dominant one is not present.

• Dominant
• Recessive

Capital letters ("E") represent ​ ​ (a)   alleles.

• dominant
• recessive
• anything you want

In a heterozygous genotype, the ___________ allele takes over in the phenotype.

• recessive

• dominant

• lower case letter

• both