Punnett Square Biology EOC Review

Which of the following is a phenotype?

• Aa

• red hair

• heterozygous

• DNA

Answer explanation

The correct choice is 'red hair' because it is a visible trait or characteristic resulting from the interaction of an organism's genotype with the environment.

Tags

NGSS.HS-LS4-3

In guinea pigs, the allele for short hair is dominant. If all the guinea pigs are born short haired what are the possible genotypes of the parents? (There are two possible combinations.)

• Ss + Ss

• SS + SS

• SS + Ss

• ss + ss

Answer explanation

The possible genotypes of the parents for all short-haired guinea pigs are SS + Ss and SS + SS, as short hair is dominant and all offspring are short haired.

Tags

NGSS.HS-LS3-1

Two heterozgyous tall pea plants are crossed. What is the expected phenotypic outcome for the offspring?

• 100% tall

• 50% tall, 50% short

• 75% tall, 25% short

• 100% short

Answer explanation

When two heterozygous tall pea plants are crossed, the expected phenotypic outcome for the offspring is 75% tall and 25% short due to the 3:1 phenotypic ratio predicted by Mendel's laws of inheritance.

Tags

NGSS.HS-LS3-1

If one allele for a trait is dominant and the other allele is recessive, which trait will be visible? The dominant allele or the recessive allele?

• Dominant will be visible because it is blocked by the recessive allele.

• Dominant will be visible because it hides or blocks the recessive allele.

• Recessive will be visible because it is blocked by the dominant allele.

• Recessive will be visible because it hides or blocks the dominant allele.

Answer explanation

Dominant will be visible because it hides or blocks the recessive allele.

Tags

NGSS.HS-LS3-1

What is the genotype for a pea plant heterozygous for round seeds (R), and homozygous recessive for green seeds (y)?

• Ry

• RRyy

• RrYy

• Rryy

Answer explanation

The genotype for a pea plant heterozygous for round seeds (R) and homozygous recessive for green seeds (y) is Rryy because it shows the dominant trait for round seeds (R) and the recessive trait for green seeds (yy).

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

Using the dihybrid cross and key provided, what is the probability of the offspring being tall and white?

• 9

• 2

• 3

• 6

Answer explanation

The probability of the offspring being tall and white is 3, as determined by the dihybrid cross and key provided.

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

Match the following

• physical or "expressed" traits

• genotype definition

• green round, yellow wrinkled

• genotype examples

• GgRr, GGRr, ggrr

• phenotype definition

• allele (letter) combinations

• phenotype examples

Snowshoe hares can be found living in the Rocky Mountains of New Mexico. During the summer months, when there is no snow on the ground, the snowshoe hare’s coat color is typically brown. During the winter months, when the mountains are covered in snow, the snowshoe hare’s coat is typically white. Which statement describes the genetic basis for the seasonal changes in coat color?

• The snow causes mutations in the genes that regulate coat color so that snowshoe hares are adapted to their environment during the winter months.

• The genes that control coat color are regulated by hormone signals that are altered by changes in environmental factors.

• Sunlight causes cancer cells to develop in the bodies of snowshoe hares, resulting in an apparent brown-colored coat as a result of hair loss.

• The genes that control coat color in snowshoe hares are deleted from the genome during the summer months.

Answer explanation

The genes that control coat color are regulated by hormone signals that are altered by changes in environmental factors.

Tags

B.6(D)

A genetic cross involving two unlinked genes is represented. AaGG x aaGg

Which genotype is NOT possible in the offspring produced by the cross?

• AaGG

• Aagg

• aaGg

• aaGG

Answer explanation

The genotype 'Aagg' is not possible in the offspring because it requires both parents to contribute a lowercase 'a' allele, which is not present in the parent genotype AaGG.

In Texas Longhorn cattle, coat coloration is an inherited trait. What is the genetic basis of coat-color variation in Texas Longhorn cattle?

• Differences in the nucleotide sequences of genes

• Differences in the numbers of chromosomes in cells

• Differences in the diets of individual cattle

• Differences in the environmental conditions of different geographic areas

Answer explanation

The genetic basis of coat-color variation in Texas Longhorn cattle is differences in the nucleotide sequences of genes, which determine the expression of specific coat color genes.

Tags

B.6(A)