Genetics Study Guide

We all have two alleles, or versions, of each gene. Being ​ (a)   for a particular gene means you inherited two identical versions. It's the opposite of a ​ (b)   genotype, where the alleles are different. People who have recessive traits, like blue eyes or red hair, are always homozygous for that gene.

• homozygous
• heterozygous

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NGSS.HS-LS3-2

​ (a)   are always expressed when the connected allele is dominant, even if only one copy of the dominant trait exists. ​ (b)   are expressed only if both the connected alleles are recessive.

• Dominant traits
• Recessive traits

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NGSS.HS-LS3-1

A version of a gene is called a(n)

• allele

• characteristic

• specific gene

• trait

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NGSS.HS-LS3-1

An organism’s genetic makeup; the pair of alleles for a trait is called a(n)

• dominant trait

• genotype

• phenotype

• recessive trait

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NGSS.HS-LS3-1

NGSS.HS-LS3-2

An organism’s physical expression of a trait is called a(n)

• dominant trait

• genotype

• phenotype

• recessive trait

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NGSS.HS-LS3-1

In a Punnett square, a lower case letter stands for a ____________ allele.

• dominant

• recessive

• homozygous

• heterozygous

Which of the following alleles is homozygous (purebred) recessive?

• Tt
• tt
• TT
• t

Which of the following genotypes is homozygous dominant?

• A

• Aa

• AA

• aa

How many chromosomes are in a human egg cell and passed down from a mother to her child?

• 23
• 46
• 92

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NGSS.HS-LS3-1

G = green, g = yellow
The genotype for a yellow plant is...

• GG
• Gg
• gg
• all of the choices result in yellow

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NGSS.HS-LS3-1

NGSS.HS-LS3-2