Genetics and Traits Overview

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What is the definition of genetics?

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Genetics is the scientific study of heredity and the variation of inherited characteristics.

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NGSS.HS-LS1-1

NGSS.HS-LS3-1

NGSS.HS-LS3-2

Front

What does it mean for a trait to be dominant?

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A dominant trait is one that masks the presence of another trait, meaning it will be expressed in the phenotype even if only one copy of the allele is present.

Front

What is a homozygous dominant genotype?

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A homozygous dominant genotype consists of two identical dominant alleles, represented as 'BB'.

Tags

NGSS.HS-LS3-2

Front

What is a heterozygous genotype?

Back

A heterozygous genotype consists of one dominant and one recessive allele, represented as 'Bb'.

Tags

NGSS.HS-LS1-1

Front

What is the genotype ratio of a cross between a homozygous dominant (BB) and a heterozygous (Bb) parent?

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The genotype ratio is 2 BB : 2 Bb, or simplified, 1 BB : 1 Bb.

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What is incomplete dominance?

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Incomplete dominance is a situation in which one allele is not completely dominant over another, resulting in a blended phenotype.

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What is codominance?

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Codominance occurs when both alleles in a heterozygous genotype are fully expressed, resulting in offspring with a phenotype that shows both traits.

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What is a recessive allele?

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A recessive allele is one that is masked by a dominant allele and is only expressed in the phenotype when two copies are present (homozygous recessive, 'bb').

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What is an allele?

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An allele is a variant form of a gene that can produce different traits.

Tags

NGSS.HS-LS3-2

Front

What is the phenotype?

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The phenotype is the observable physical or biochemical characteristics of an organism, determined by both genetic makeup and environmental influences.