Biology Midterm Chapter 9

Using a six-sided die, what is the probability of rolling either a 5 or a 6? Select one: a. 1/6 + 1/6 = 1/3 b. 1/6 c. 1/6 + 1/6 = 2/3 d. 1/6 × 1/6 = 1/36

a. 1/6 + 1/6 = 1/3

Which of the following statements best represents the theory of pangenesis developed by Hippocrates? Select one: a. Particles called pangenes, which originate in each part of an organism's body, collect in the sperm or eggs and are passed on to the next generation. b. Heritable traits are influenced by the environment and the behaviors of the parents. c. Pregnancy is a spontaneous event, and the characteristics of the offspring are determined by the gods. d. Offspring inherit the traits of either the mother or the father, but not both.

a. Particles called pangenes, which originate in each part of an organism's body, collect in the sperm or eggs and are passed on to the next generation.

Mendel's law of independent assortment states that Select one: a. each pair of alleles sort independently of the other pairs of alleles during gamete formation. b. chromosomes sort independently of each other during mitosis and meiosis. c. independent sorting of genes produces polyploid plants under some circumstances. d. genes are sorted concurrently during gamete formation.

a. each pair of alleles sort independently of the other pairs of alleles during gamete formation.

Imagine that beak color in a finch species is controlled by a single gene. You mate a finch homozygous for orange (pigmented) beak with a finch homozygous for ivory (unpigmented) beak and get numerous offspring, all of which have a pale, ivory-orange beak. This pattern of color expression is most likely to be an example of Select one: a. incomplete dominance. b. pleiotropy. c. codominance. d. polygenic inheritance.

a. incomplete dominance.

What is the normal complement of sex chromosomes in a human male? Select one: a. one X chromosome and one Y chromosome b. two X chromosomes and one Y chromosome c. two Y chromosomes d. one Y chromosome

a. one X chromosome and one Y chromosome

Most genetic disorders of humans are caused by Select one: a. recessive alleles. b. a mutation that occurs in the egg, sperm, or zygote. c. dominant alleles. d. multiple alleles.

a. recessive alleles.

If A is dominant to a and B is dominant to b, what is the expected phenotypic ratio of the cross AaBb × AaBb? Select one: a. 1:1:1:1 b. 9:3:3:1 c. 8:4:2:2 d. 16:0:0:0

b. 9:3:3:1

Dr. Smith's 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. Smith's parents could have which of the following genotypes? Select one: a. Dd and DD b. Dd and Dd c. DD and dd d. dd and dd

b. Dd and Dd

After reading the paragraphs below, answer the questions that follow. Cats normally have a total of 18 toes, 5 on each front paw and 4 on each back paw. But some cats express the dominant phenotype for polydactyly, which results in the development of extra toes on one or more paws. Jake, a Canadian tabby cat, has 28 toes and is recognized by the Guinness Book of World Records as the cat with the most toes. Suppose that Jake mates with a female cat, Lucy, who has 18 total toes. Over several years, they have multiple litters and a total of 16 kittens (10 males and 6 females). The total number of toes on each kitten ranges from 21 to 25. If we use the letter P to represent the polydactyly gene, what is Jake's genotype? Select one: a. pp b. PP c. Pp d. You cannot determine Jake's genotype from this information.

b. PP

Which of the following statements regarding cross-breeding and hybridization is false? Select one: a. The hybrid offspring of an F1 cross are the F2 generation. b. The hybrid offspring of a cross are the P1 generation. c. The parental plants of a cross are the P generation. d. The offspring of two different varieties are called hybrids.

b. The hybrid offspring of a cross are the P1 generation.

A person with AB blood illustrates the principle of Select one: a. pleiotropy. b. codominance. c. incomplete dominance. d. polygenic inheritance.

b. codominance.

The expression of both alleles for a trait in a heterozygous individual illustrates Select one: a. incomplete dominance. b. codominance. c. polygenic inheritance. d. pleiotropy.

b. codominance.

Most people afflicted with recessive disorders are born to parents who were Select one: a. both affected by the disease. b. not affected at all by the disease. c. subjected to some environmental toxin that caused the disease in their children. d. slightly affected by the disease, showing some but not all of the symptoms.

b. not affected at all by the disease.

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 couple's first-born child will be female and that their second-born child will be male? Select one: a. 20% b. 75% c. 25% d. 50%

c. 25%

Which of the following statements regarding genotypes and phenotypes is false? Select one: a. Alleles are alternate forms of a gene. b. The expressed physical traits of an organism are called its phenotype. c. An organism with two different alleles for a single trait is said to be homozygous for that trait. d. The genetic makeup of an organism constitutes its genotype.

c. An organism with two different alleles for a single trait is said to be homozygous for that trait.

Research since Mendel's time has established that the law of segregation of genes during gamete formation Select one: a. is invalid. b. applies to all forms of life. c. applies to all sexually reproducing organisms. d. applies to all asexually reproducing organisms.

c. applies to all sexually reproducing organisms.

A carrier of a genetic disorder who does not show symptoms is most likely to be ________ to transmit it to offspring. Select one: a. homozygous for the trait and able b. homozygous for the trait and unable c. heterozygous for the trait and able d. heterozygous for the trait and unable

c. heterozygous for the trait and able

Which of the following terms refers to a situation where a single phenotypic character is determined by the additive effects of two or more genes? Select one: a. incomplete dominance b. pleiotropy c. polygenic inheritance d. codominance

c. polygenic inheritance

Varieties of plants in which self-fertilization produces offspring that are identical to the parents are referred to as Select one: a. monohybrid crosses. b. hybrids. c. true-breeding. d. the F2 generation.

c. true-breeding.

All the offspring of a cross between a black-eyed Mendelian and an orange-eyed Mendelian have black eyes. What is the expected phenotypic ratio of a cross between two orange-eyed Mendelian? Select one: a. 1 black-eyed:3 orange-eyed b. 1 black-eyed:0 orange-eyed c. 3 black-eyed:1 orange-eyed d. 0 black-eyed:1 orange-eyed

d. 0 black-eyed:1 orange-eyed

The phenotypic ratio resulting from a dihybrid cross of two heterozygote individuals showing independent assortment is expected to be Select one: a. 1:2:1 b. 3:1 c. 9:1:1:3 d. 9:3:3:1

d. 9:3:3:1

A colorblind woman marries a man who is not colorblind. All of their sons, but none of their daughters, are colorblind. Which of the following statements correctly explains these results? Select one: a. The gene for color vision is found on the Y chromosome. b. The gene for color vision is codominant with the gene for sex determination. c. The gene for color vision is incompletely dominant to the gene for sex determination. d. The gene for color vision is found on the X chromosome.

d. The gene for color vision is found on the X chromosome.

A monohybrid cross is Select one: a. a breeding experiment in which the parental varieties have only one prominent trait. b. the second generation of a self-fertilized plant. c. a breeding experiment in which the parental varieties have only one trait in common. d. a breeding experiment in which the parental varieties differ in only one character.

d. a breeding experiment in which the parental varieties differ in only one character.

A testcross is Select one: a. a mating between two individuals heterozygous for the trait of interest. b. a mating between two individuals of unknown genotype. c. a mating between an individual of unknown genotype and an individual heterozygous for the trait of interest. d. a mating between an individual of unknown genotype and an individual homozygous recessive for the trait of interest.

d. a mating between an individual of unknown genotype and an individual homozygous recessive for the trait of interest.

All the offspring of a cross between a red-flowered plant and a white-flowered plant have pink flowers. This means that the allele for red flowers is ________ to the allele for white flowers. Select one: a. dominant b. codominant c. recessive d. incompletely dominant

d. incompletely dominant

How many sex chromosomes are in a human gamete? Select one: a. four b. two c. three d. one

d. one

Mendel conducted his most memorable experiments on Select one: a. fruit flies. b. guinea pigs. c. roses. d. peas.

d. peas.

The alleles of a gene are found at ________ chromosomes. Select one: a. different loci on homologous b. the same locus on nonhomologous c. different loci on nonhomologous d. the same locus on homologous

d. the same locus on homologous