Genetics STAAR Review

Front

What is a genotype?

Back

A genotype is the genetic makeup of an organism, represented by the combination of alleles (e.g., AA, Aa, aa).

Front

What is a phenotype?

Back

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

Front

Why do organisms have two alleles for each gene?

Back

Organisms have two alleles for each gene because they inherit one allele from each parent.

Front

What are alleles?

Back

Alleles are different forms of a gene that can exist at a specific locus on a chromosome.

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What is a dominant trait?

Back

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

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What is a recessive trait?

Back

A recessive trait is a trait that is only expressed in the phenotype when two recessive alleles are present.

Front

What does homozygous mean?

Back

Homozygous refers to having two identical alleles for a particular gene (e.g., AA or aa).

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What does heterozygous mean?

Back

Heterozygous refers to having two different alleles for a particular gene (e.g., Aa).

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What is a purebred organism?

Back

A purebred organism is one that has a homozygous genotype for a specific trait, resulting in offspring that are genetically uniform.

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What is a hybrid organism?

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A hybrid organism is one that has a heterozygous genotype, resulting from the cross of two different purebred organisms.