Chapter 12 Achieve Assignment

What is Snowflake's genotype? Based on Snowflake's genotype, what is the genotype of squirrel D?

gg Gg

Which statement describes a phenotype?

the physical trait produced by an organism's genetic makeup

In certain breeds of chickens, black feathers (𝐶𝐵CB ) are codominant with white feathers (𝐶𝑊CW ). What is the genotype of a chicken of this breed with a mix of black and white feathers?

𝐶𝐵𝐶𝑊CB⁢CW

Tail length in the manx cat is a trait that displays incomplete dominance. There are two alleles for tail length, one for a long tail (TL) and one for no tail (TN). Cats that are homozygous for the long‑tail allele (TLTL) have long tails, whereas heterozygous (TLTN) cats are tailless. Cats with the genotype (TNTN) die during embryonic development. If two tailless cats have a litter of kittens, what are the predicted phenotype percentages of the offspring?

33% long tailed, 67% tailless

Which of the statements can be concluded from Gregor Mendel's experiments with pea plants?

A heterozygous phenotype is the same as a homozygous dominant phenotype. Alleles of different genes are inherited independently of each other.

Identify the statement that defines an individual who is heterozyous for a gene.

An individual inherits two different alleles for a gene.

The figure represents a pair of homologous chromosomes. Assign the appropriate term to each component.

.

During his experiments with pea plants, Gregor Mendel crossed plants that were heterozygous for two traits with one another in order to determine laws of inheritance. The Punnett square shows the results of this cross. Select the statements that are true about Mendel's law of independent assortment.

Allele pairs do not influence one another during segregation for gamete formation. A dihybrid cross between heterozygous individuals will result in exactly nine genotypes.

Mendel formulated the law of independent assortment to explain the basic rules of inheritance based on his experiments with pea plants. With the modern understanding of chromosomes, alleles, and the process of gamete formation, what is the physical basis for the law of independent assortment?

Alleles on nonhomologous chromosomes separate randomly into gametes during meiosis.

The dominance pattern of a gene can be determined from the phenotypes of the parents and offspring. In the examples below, assume that each parent is homozygous for the specific allele and that the progeny are heterozygous. Classify each example as either complete dominance, incomplete dominance, or codominance.

Complete dominance A pea plant with all purple flowers and a pea plant with all white flowers produce a pea plant with all purple flowers. Incomplete dominance A black sheep and a white sheep produce a gray lamb. A mother with straight hair and a father with curly hair have a son with wavy hair. Codominance A mother with type A blood and a father with type B blood have a daughter with type AB blood. A green fish and a yellow fish have mottled green and yellow offspring.

Mendel proposed the law of segregation to explain how hereditary particles are passed down from parents to offspring. With the current understanding of chromosomes, alleles, and the process of cell division, what is the physical basis for the law of segregation?

Homologous chromosomes separate into different daughter cells in anaphase I of meiosis.

Lily, a student in an introductory biology class, learns that some alleles, such as blood type alleles IA and IB, are codominant with one another. She also learns that blood type allele i is recessive to the IA and IB alleles. Lily knows that her mother has blood type AB and her father has blood type A, but she does not know her own blood type. Identify all the possible genotypes for blood type that Lily may have.

IAIA IBi IAIB IAi

Which of the statements about incomplete dominance are true?

If homozygous dominant mice have black fur, and homozygous recessive mice have white fur, then heterozygous mice have gray fur. Heterozygous individuals have a phenotype intermediate to the homozygous dominant and homozygous recessive phenotypes.

Why are linked genes often inherited together?

Linked genes are close together on the same chromosome.

How is a true breeding yellow‑seeded pea plant different from a hybrid yellow‑seeded pea plant?

They have the same phenotype but different genotypes.

Earwax type is a Mendelian human trait. Specifically, wet earwax (W) is a dominant allele, and dry earwax (w) is a recessive allele. Given parents with Ww and ww genotypes, what is the probability that their child will have a dry earwax phenotype? Enter your answer as a percentage.

WwwWwwwwWwww probability: 50%

Hemophilia is a blood disorder caused by an X‑linked recessive trait. A man with hemophilia and a woman who does not have hemophilia and is not a carrier for the trait are considering having children. Complete the Punnett square to show the allele combinations that are possible among the offspring of this couple.

X^H X^h / X^H X^h---------------------------X^H Y / X^H Y100%

Which statement describes recessive alleles?

any allele whose presence can be masked by another allele

A homozygous brown‑haired horse is mated with a homozygous white‑haired horse. If the alleles for hair color are codominant, which phenotype do you expect their foals to have?

both brown and white hair

In a particular species of octopus, long arm length is completely dominant over short arm length. If an octopus of this species has short arms, what is its genotype?

dd