Mastering Biology Ch. 19

If an individual with type O blood marries an individual with type AB blood, what are the possible blood types of their children?

A and B.

Which of the following statements is NOT true for a person who is heterozygous for sickle cell?

A person who is heterozygous for sickle cell tends to die at a younger age than a person with sickle-cell anemia does.

Consider the hypothetical X-linked recessive gene M. Suppose a woman expresses this gene. So does her husband. What are the chances that a child of theirs will NOT express this gene?

All of the children will express the trait.

Which of the following could be detected by preparing a karyotype?

Klinefelter syndrome.

Which of the following events or processes can result in Patau syndrome, Turner Syndrome, or Klinefelter syndrome?

Nondisjunction.

Based on what you know about two-trait inheritance, what can you say about the gametes produced by a female with the genotype AaDd that could NOT be possible?

One of her gametes might be AaDd.

What is tyrosinase?

Tyrosinase is an enzyme that facilitates the conversion of tyrosine to melanin.

What can we say about the frequency of X-linked recessive traits?

X-linked recessive traits are more common in males than in females.

What is the likelihood that a parent with type AB blood would have a child with type O blood?

0%.

What is the probability that a woman who is a carrier for the red-green color-blindness allele and a man who is color blind will have a child who is NOT color blind?

50%.

In humans, the allele for a widow's peak (W) is dominant and the allele for a straight hairline (w) is recessive. This trait shows complete dominance. Which of the following represents the possible phenotypes in the offspring of two parents, both with a straight hairline?

All offspring will have a straight hairline.

The basic laws of genetic inheritance were described by ________.

Gregor Mendel.

Examination of a karyotype reveals 23 pairs of chromosomes, with each homologous pair illustrating similar size and centromere location. Which of the following can be concluded from this karyotype?

The individual is a female.

A man carries a Y-linked trait. He will pass this trait on to __________.

all of his sons.

A homozygous trait can be ________.

either dominant or recessive.

A female is diagnosed with hemophilia, a condition caused by an X-linked recessive gene. While checking her medical history, the doctor will most likely discover that ________.

her father had hemophilia but her mother did not have the disorder.

What is the likelihood that a man with hemophilia mating with a woman who is homozygous for the normal form of the blood clotting factor gene will have a son with hemophilia?

0%.

Two parents are heterozygous for familial hypercholesterolemia, with blood cholesterol levels two to three times the normal level. What is the probability that their child will be unaffected by this disorder?

25%.

Having a chin dimple (cleft chin) is dominant over having no chin dimple. Having long eyelashes is dominant over having short eyelashes. Jack and Jill are both heterozygous for a chin dimple and long eyelashes. What are the chances that their baby will have no chin dimple and short eyelashes?

The chances are about 1 in 16 that their child will have no chin dimple and short eyelashes.

Testosterone is responsible for the development of the male reproductive system, and it is produced by the testes. The development of the testes depends on the presence of a Y chromosome. What might occur if the Y chromosome is present, but the testes are unable to produce testosterone?

The testes would be present, but further male development would be arrested.

An unaffected man whose mother had sickle-cell anemia marries an unaffected woman whose father had sickle-cell anemia. Which of the following statements about their offspring is NOT true?

They must all have the sickle-cell trait.

True or false. In codominance, both phenotypes are expressed in heterozygotes; but in incomplete dominance, the heterozygotes exhibit a phenotype that is intermediate between the two homozygotes.

True.

True or false. X-linked recessive disorders are more commonly expressed in males than in females because males have only one copy of the X chromosome.

True.

Which of the following parental genotypes would produce offspring in a 1:1:1:1 phenotypic ratio?

aaBb x Aabb.

A recessive phenotype will be expressed when __________.

both alleles present are recessive.

In the human ABO blood-typing system, an individual with A and B alleles will express both A and B phenotypes on his or her red blood cells. This is an example of __________.

codominance.

Dominant alleles that cause disease are especially dangerous because __________.

heterozygous individuals will develop the disease.

Nondisjunction in meiosis I results in failure of __________.

homologous chromosomes to separate.

The law of segregation states that __________.

in the formation of gametes, alleles separate from each other so that each gamete receives only one allele.

When a straight-haired parent and a curly-haired parent have a wavy-haired child, this is an example of __________.

incomplete dominance.

All of the following human traits are determined by the interaction of multiple genes and alleles, EXCEPT __________.

sickle cell anemia.

Alterations in chromosomal structure or number that occur during mitosis or meiosis are seldom seen because __________.

the altered genes are crucial to development and the organism does not survive to birth.