Genetics: Basics

Front

What is a recessive allele?

Back

A recessive allele is a trait that is hidden when a dominant allele is present. It only expresses itself when two recessive alleles are present.

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What is a genotype?

Back

A genotype is the combination of alleles (letters) for a specific trait, such as DD, Dd, or dd.

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What does homozygous mean?

Back

Homozygous refers to having two identical alleles for a trait, such as DD or dd.

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What does heterozygous mean?

Back

Heterozygous refers to having two different alleles for a trait, such as Dd.

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What is a phenotype?

Back

A phenotype is the observable physical or biochemical characteristics of an organism, determined by its genotype.

Front

What is the genotype of a white plant if a purple plant (Pp) is crossed with it?

Back

The genotype of the white plant is pp.

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What is a dihybrid cross?

Back

A dihybrid cross is a genetic cross that involves two traits, represented by two pairs of alleles, such as AaBb x AaBb.

Front

What is a dominant allele?

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A dominant allele is a trait that is expressed in the phenotype even when only one copy is present.

Front

What is the difference between genotype and phenotype?

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Genotype refers to the genetic makeup (alleles) of an organism, while phenotype refers to the physical expression of those genes.

Front

What does it mean for an organism to be homozygous dominant?

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An organism is homozygous dominant if it has two dominant alleles for a trait, such as DD.