hw#13

Which one of the following is an example of incomplete dominance in humans? B) hypercholesterolemia C) skin color E) None of the choices are correct.

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Assuming that the probability of having a female child is 50% and the probability of having a male child is also 50%, what is the probability that a coupleʹs first-born child is female and second-born child is male? A) 25% B) 50% C) 75% D) 100% E) None of the choices are correct

A) 25%

Given the sex determination system in bees, we can expect that A) female bees produce eggs by meiosis, while male bees produce sperm by mitosis. B) female bees produce eggs by mitosis, while male bees produce sperm by meiosis. C) male and female bees produce sperm and eggs by meiosis. D) male and female bees produce sperm and eggs by mitosis. E) female bees produce eggs by meiosis but male bees do not produce sperm or eggs. 18) 3

A) female bees produce eggs by meiosis, while male bees produce sperm by mitosis.

A carrier of a genetic disorder who does not show symptoms is most likely to be __________ to transmit it to offspring. A) heterozygous for the trait and able B) heterozygous for the trait and unable C) homozygous for the trait and able D) homozygous for the trait and unable E) None of the choices are correct.

A) heterozygous for the trait and able

Using a six-sided die, what is the probability of rolling either a 5 or a 6? A) 1/6 X 1/6 = 1/36 B) 1/6 + 1/6 = 1/3 C) 1/6 + 1/6 = 2/3 D) 1/6 + 1/6 = 1/12 E) 1/6

B) 1/6 + 1/6 = 1/3

Research since Mendelʹs time has established that the law of the segregation of genes during gamete formation A) applies to all forms of life. B) applies to all sexually reproducing organisms. C) applies to all asexually reproducing organisms. D) applies only to unicellular organisms. E) is invalid.

B) applies to all sexually reproducing organisms.

Any gene located on a sex chromosome A) is called a recessive gene. B) is called a sex-linked gene. C) is called a dominant allele. D) will exhibit pleiotropy. E) will exhibit codominance.

B) is called a sex-linked gene.

The vast majority of people afflicted with recessive disorders are born to parents who were A) both affected by the disease. B) not affected at all by the disease. C) slightly affected by the disease, showing some but not all of the symptoms. D) subjected to some environmental toxin that caused the disease in their children. E) None of the choices are correct.

B) not affected at all by the disease.

Many genetic disorders of humans are caused by A) multiple alleles. B) recessive alleles. C) drinking during pregnancy. D) a mutation that occurs in the egg, sperm, or zygote that gives rise to the affected individual. E) None of the choices are correct.

B) recessive alleles.

Dr. Smithʹs parents have normal hearing. However, Dr. Smith has an inherited form of deafness. Deafness is a recessive trait that is associated with the abnormal allele d. The normal allele at this locus, associated with normal hearing, is D. Dr. Smithʹs parents could have which of the following genotypes? A) DD and dd B) dd and dd C) Dd and Dd D) DD and DD E) None of the choices are correct.

C) Dd and Dd

Which of the following best explains why dominant alleles that cause lethal disorders are less common than recessive alleles that cause lethal disorders? A) Lethal disorders caused by dominant alleles are usually more severe than lethal disorders caused by recessive alleles. B) Unlike lethal disorders caused by recessive alleles, lethal disorders caused by dominant alleles usually cause death of the embryo. C) Most individuals carrying a lethal dominant allele have the disorder and die before they reproduce, whereas individuals carrying a lethal recessive allele are more likely to be healthy and reproduce. D) The presence of a lethal dominant allele causes sterility. E) Many lethal recessive alleles cause enhanced disease resistance when they are present in the heterozygous state, and carriers of these alleles have more children, on average, than other people.

C) Most individuals carrying a lethal dominant allele have the disorder and die before they reproduce, whereas individuals carrying a lethal recessive allele are more likely to be healthy and reproduce.

Which one of the following is false? A) Sickle-cell disease is common in tropical Africa. B) Persons who are heterozygous for sickle-cell disease are also resistant to malaria. C) Sickle-cell disease causes white blood cells to be sickle shaped. D) All of the symptoms of sickle-cell disease result from the actions of just one allele. E) About one in 10 African Americans is a carrier of sickle-cell disease

C) Sickle-cell disease causes white blood cells to be sickle shaped.

A monohybrid cross is A) the second generation of a self-fertilized plant. B) a breeding experiment in which the parental varieties have only one trait in common. C) a breeding experiment in which the parental varieties differ in only one trait. D) a triploid plant that results from breeding two very different plants. E) None of the choices are correct.

C) a breeding experiment in which the parental varieties differ in only one trait.

Which of the following is/are recessive sex-linked human conditions? A) red-green color blindness B) muscular dystrophy C) hemophilia D) All of the choices are correct. E) None of the choices are correct

D) All of the choices are correct.

Which one of the following is false? A) The genetic makeup of an organism constitutes its genotype. B) An organism with two different alleles for a single trait is said to be heterozygous. C) Alleles are alternate forms of a gene. D) An allele that is fully expressed is referred to as recessive. E) The expressed physical traits of an organism are called its phenotype.

D) An allele that is fully expressed is referred to as recessive.

What is meant by the statement that ʺmale bees are fatherlessʺ? A) Male bees donʹt play a role in the rearing of bee young. B) Male bees are produced by budding. C) Male bees develop from fertilized eggs. D) Male bees develop from unfertilized eggs. E) The queen beeʹs mate dies before the male eggs hatch.

D) Male bees develop from unfertilized eggs.

Which one of the following is false? A) The offspring of two different varieties are called hybrids. B) Hybridization is also called a cross. C) The parental plants of a cross are the P generation. D) The hybrid offspring of a cross are the P1 generation. E) The hybrid offspring of an F1 cross are the F2 generation.

D) The hybrid offspring of a cross are the P1 generation.

Mendelʹs law of independent assortment states that A) chromosomes sort independently of each other during mitosis and meiosis. B) genes sort independently of each other in animals but not in plants. C) independent sorting of genes produces polyploid plants under some circumstances. D) each pair of alleles segregates independently of the other pairs of alleles during gamete formation. E) None of the choices are correct.

D) each pair of alleles segregates independently of the other pairs of alleles during gamete formation.

Amniocentesis and chorionic villus sampling allow for __________ and __________ of the fetus so that it can be tested for abnormalities. A) imaging . . . biochemical testing B) imaging . . . karyotyping C) sexing . . . imaging D) karyotyping . . . biochemical testing E) direct observation . . . biochemical testing

D) karyotyping . . . biochemical testing

Alleles of a gene are found at __________ chromosomes. A) the same locus on homologous mitochondrial B) the same locus on heterologous C) different loci on homologous D) different loci on heterologous E) the same locus on homologous

E) the same locus on homologous

Varieties of plants in which self-fertilization produces offspring that are identical to the parents are referred to as A) hybrids. B) the F2 generation. C) monohybrid crosses. D) independent crosses. E) true-breeding.

E) true-breeding.