Review GENETICS (B.8B)

Match the following genetic TERM with its definition or example:

• GENOTYPE

• Forms of a gene at a particular region on a chromosome. An individual inherits two _______ for each gene, one from each parent.

• PHENOTYPE

• The genetic makeup of an organism; the alleles.

• PEDIGREE CHART

• The observable physical traits of an organism; these include the organism's appearance, development, and behavior.

• PUNNETT SQUARE

• A chart that diagrams the inheritance of a trait or health condition through generations of a family.

• ALLELE

• A table in which all of the possible outcomes for a genetic cross between two individuals with known genotypes are given.

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Match the following genetic TERM with its definition or example:

• DOMINANT

• The alleles of a gene that will be expressed

  (CAPITALIZED)

• HETEROZYGOUS

• The trait or allele tends to be masked by other inherited traits. Expressed only when genotype is homozygous.

  (lowercase)

• RECESSIVE

• Same alleles inherited from each biological parent

  (AA or aa)

• HOMOZYGOUS

• Different alleles inherited from each biological parent

  (Aa)

Match the following genetic TERM with its definition or example:

• KARYOTYPE

• Any chromosome that is not a sex chromosome; Pairs 1 - 22 in Humans.

• SEX CHROMOSOMES

• Passed from parents to offspring - Structures located inside the nucleus of cells, made of protein and a single molecule of deoxyribonucleic acid (DNA).

• AUTOSOMES

• A type of chromosome that determines the sex of an individual; Pair 23 in Humans (XX or XY)

• CHROMOSOMES

• A laboratory-produced image of a person's chromosomes isolated from an individual cell and arranged in numerical order.

• GENE

• Passed from parent to child - Sequences of DNA, arranged at specific locations on chromosomes in the nucleus of cells.

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In terms of genetic material, what do you inherit from your mother?

• 22 autosomes & an 'X' sex chromosome

• 22 autosomes & an 'X or Y' sex chromosome

• 22 sex chromosomes & an 'X' autosome

• 22 sex chromosomes & an 'X or Y' autosome

Answer explanation

We get 23 chromosomes from our mother and 23 from our father for a total of 46 chromosomes.

Chromosome pairs 1 - 22 are autosomes (non-sex chromosomes) and chromosome pair #23 is an X (from the mother) + X OR Y (from the father).

XX will determine a female, XY determines a male).

Tags

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In terms of genetic material, what do you inherit from your father?

• 22 autosomes & an 'X' sex chromosome

• 22 autosomes & an 'X or Y' sex chromosome

• 22 sex chromosomes & an 'X' autosome

• 22 sex chromosomes & an 'X or Y' autosome

Answer explanation

We get 23 chromosomes from our mother and 23 from our father for a total of 46 chromosomes.

Chromosome pairs 1 - 22 are autosomes (non-sex chromosomes) and chromosome pair #23 is an X (from the mother) + X OR Y (from the father).

XX will determine a female, XY determines a male).

Tags

NGSS.HS-LS3-1

In cocker spaniels the allele for a black coat color (B) is dominant over the allele for a brown coat color (b). If a brown cocker spaniel is crossed with a heterozygous black cocker spaniel, which of the following genotypic ratios can be expected?

• 0 BB: 2 Bb: 2 bb

• 1 BB: 2 Bb: 1 bb

• 2 BB: 0 Bb: 2 bb

• 2 BB: 1 Bb: 0 bb

Answer explanation

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Tomato plants usually have hairy stems. Hairless stems are present in tomato plants that are homozygous recessive for this trait. If the stem characteristics are determined by a single gene, what is the expected outcome of crossing two tomato plants that are heterozygous for hairy stems?

• 75% hairy stems: 25% hairless stems

• 100% hairy stems

• 100% hairless stems

• 50% hairy stems: 50% hairless stems

Answer explanation

Tags

NGSS.HS-LS3-1

Normal fruit flies have brownish-yellow bodies, and this body color is dominant. A mutation in the gene for body color can produce flies with an ebony body color. A homozygous normal fruit fly (e⁺e⁺) is crossed with a homozygous ebony fly (ee).

What is the predicted outcome of this genetic cross?

• All the offspring will have ebony bodies.

• Of the offspring, 75% will have brownish-yellow bodies, and 25% will have ebony bodies.

• All the offspring will have brownish-yellow bodies.

• Of the offspring, 75% will have ebony bodies and 25% will have brownish-yellow bodies.

Answer explanation

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Facial dimples and free ear lobes are both considered dominant human traits. What are the expected phenotypes of the offspring of a female with dimples and free earlobes (DDFf) and a male with no dimples and attached earlobes (ddff)?

• 50% with dimples and free earlobes, and 50% with dimples and attached earlobes

• 50% with dimples and free earlobes, and 50% with no dimples and attached earlobes

• 75% with dimples and free earlobes, and 25% with no dimples and attached earlobes

• 75% with dimples and attached earlobes, and 25% with no dimples and free earlobes

Answer explanation

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The four butterflies in the illustration represent the offspring in the F₁ generation.

Which statement is best supported by the phenotypes of these offspring?

• The F₁ generation is composed of only males

• Two of the offspring in the F₁ generation will not be able to reproduce

• The F₁ generation is the result of a dihybrid cross

• Two of the offspring in the F₁ generation will experience a spontaneous mutation

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