bio ch 9

A monohybrid cross is A) a breeding experiment in which the parental varieties differ in only one character. B) a breeding experiment in which the parental varieties have only one prominent trait. C) the second generation of a self-fertilized plant. D) a breeding experiment in which the parental varieties have only one trait in common.

A

A woman has been trying to conceive for several years, unsuccessfully. At a fertility clinic, they discover that she has blocked fallopian tubes. Using modern technologies, some of her eggs are removed, fertilized with her husband's sperm, and implanted into her uterus. The procedure is successful, but the couple discovers that their new son is color-blind and has blood type O. The woman claims that the child can't be theirs since she has blood type A and her husband has type B. Also, neither parent is color-blind, although one grandparent (the woman's father) is also color-blind. As a genetic counselor, you would explain to the parents that A. each parent could have contributed one recessive allele, resulting in type O blood. B. it is possible for the baby to have type O blood, since type O is inherited through a dominant allele. C. the eggs must have been accidentally switched, since a type A parent and a type B parent can have any type children except O. D. the eggs must have been accidentally switched, since the baby's blood type has to match one of his parents.

A

According to scientists, about what percentage of men currently living in Central Asia may be descended from the Mongolian ruler Genghis Khan? 8% 25% 40% 4%

A

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. A. incompletely dominant B. recessive C. dominant D. codominant

A

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

A

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? A. 25% B. 50% C. 75% D. 20%

A

Crossing over ________ genes into assortments of ________ not found in the parents. A) recombines linked . . . alleles B) combines linked . . . genes C) combines unlinked . . . alleles D)recombines unlinked . . . genes

A

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? A. Dd and Dd B. dd and dd C. DD and dd D. Dd and DD

A

Female inheritance patterns cannot be analyzed by simply studying the X chromosome because the X chromosome is obtained from both father and mother. one X chromosome is deactivated in females. the X chromosome is too large to analyze effectively the X chromosome sometimes exchanges genetic information with the Y chromosome

A

In regard to the baby's color blindness, a sex-linked recessive trait, you explain that A) since color blindness is sex-linked, a son can inherit color blindness if his mother has the recessive color blindness allele. B) the baby's father must have a recessive allele for color blindness. C) the eggs must have been accidentally switched, since males inherit sex-linked traits only from their fathers. D) color blindness often appears randomly, even if neither parent is color-blind.

A

Mendel conducted his most memorable experiments on A) peas. B) guinea pigs. C) fruit flies. D) roses.

A

Recessive X-linked traits are more likely to be expressed in a male fruit fly than a female fruit fly because A) the male's phenotype results entirely from his single X-linked gene. B) the male chromosome is more susceptible to mutations. C) males are haploid. D) the male chromosome is more fragile than the female chromosome

A

The expression of both alleles for a trait in a heterozygous individual illustrates A. codominance. B. polygenic inheritance. C. pleiotropy. D. incomplete dominance.

A

What is the normal complement of sex chromosomes in a human male? A) one X chromosome and one Y chromosome B) one Y chromosome C) two Y chromosomes D) two X chromosomes and one Y chromosome

A

Which of the following kinds of data could be used to map the relative position of three genes on a chromosome? A) the frequencies with which the corresponding traits occur together in offspring B) the frequencies with which the genes exhibit incomplete dominance over each other C) the frequencies of mutations in the genes D) the frequencies with which the genes are inherited from the mother and from the father

A

Which of the following statements regarding genetic testing is false? A. human genetic diseases are treatable if caught early. B. Genetic testing before birth requires the collection of fetal cells. C. Carrier testing helps determine if a person carries a potentially harmful disorder. D. The screening of newborns can catch inherited disorders right after birth.

A

Which of the following statements regarding hypotheses about inheritance is false? A) The blending hypothesis suggests that all of the traits of the offspring come from either the mother or the father. B) The blending hypothesis does not explain how traits that disappear in one generation can reappear in later generations. C) Contrary to the theory of pangenesis, somatic cells do not influence eggs or sperm. D) The theory of pangenesis incorrectly suggests that reproductive cells receive particles from somatic cells.

A

A color-blind woman marries a man who is not color-blind. All of their sons, but none of their daughters, are color-blind. Which of the following statements correctly explains these results? A) The gene for color vision is found on the Y chromosome. B) The gene for color vision is found on the X chromosome. C) The gene for color vision is incompletely dominant to the gene for sex determination. D) The gene for color vision is codominant with the gene for sex determination.

B

A person with AB blood illustrates the principle of A. polygenic inheritance. B. codominance. C.pleiotropy. D. incomplete dominance.

B

A testcross is A. a mating between an individual of unknown genotype and an individual heterozygous for the trait of interest. B. a mating between an individual of unknown genotype and an individual homozygous recessive for the trait of interest. C. a mating between two individuals heterozygous for the trait of interest. D. a mating between two individuals of unknown genotype.

B

All the offspring of a cross between a black-eyed mendelien and an orange-eyed mendelien have black eyes. What is the expected phenotypic ratio of a cross between two orange-eyed mendeliens? A) 1 black-eyed:3 orange-eyed B) 0 black-eyed:1 orange-eyed C) 1 black-eyed:0 orange-eyed D) 3 black-eyed:1 orange-eyed

B

Given the sex determination system in bees, we can expect that A) male and female bees will produce sperm and eggs by mitosis. B) female bees will produce eggs by meiosis, while male bees will produce sperm by mitosis. C) male and female bees will produce sperm and eggs by meiosis. D) female bees will produce eggs by mitosis, while male bees will produce sperm by meiosis.

B

Imagine that we mate two black Labrador dogs with normal vision and find that three of the puppies are like the parents, but one puppy is chocolate with normal vision and another is black with PRA (progressive retinal atrophy, a serious disease of vision). We can conclude that A. the same alleles that control coat color can also cause PRA. B. the alleles for color and vision segregate independently during gamete formation. C. both of the parents are homozygous for both traits. D. the alleles for color and vision segregate dependently during gamete formation.

B

Mendel's law of independent assortment states that A. chromosomes sort independently of each other during mitosis and meiosis. B. each pair of alleles segregates independently of the other pairs of alleles during gamete formation. C. independent sorting of genes produces polyploid plants under some circumstances. D. genes are sorted concurrently during gamete formation.

B

Sex-linked conditions are more common in men than in women because A) the genes associated with the sex-linked conditions are linked to the Y chromosome, which determines maleness. B) men need to inherit only one copy of the recessive allele for the condition to be fully expressed. C) the sex chromosomes are more active in men than in women. D) men acquire two copies of the defective gene during fertilization. Previous Answers

B

The mechanism that "breaks" the linkage between linked genes is A) codominance. B) crossing over. C) independent assortment. D) pleiotropy.

B

Which of the following statements is false? A. The four blood types result from various combinations of the three different ABO alleles. B. Incomplete dominance supports the blending hypothesis. C. The impact of a single gene on more than one character is called pleiotropy. D. ABO blood groups can provide evidence of paternity.

B

Which of the following statements regarding cross-breeding and hybridization is false? A) The parental plants of a cross are the P generation. B) The hybrid offspring of a cross are the P1 generation. C) The hybrid offspring of an F1 cross are the F2 generation. D) The offspring of two different varieties are called hybrids.

B

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

B

A carrier of a genetic disorder who does not show symptoms is most likely to be ________ to transmit it to offspring. A. homozygous for the trait and unable B. homozygous for the trait and able C. heterozygous for the trait and able D. heterozygous for the trait and unable

C

All the offspring of a cross between a black-eyed mendelien and an orange-eyed mendelien have black eyes. This means that the allele for black eyes is ________ the allele for orange eyes. A) recessive to B) codominant to C) dominant to D) more aggressive than

C

Genes located close together on the same chromosomes are referred to as ________ genes and generally ________ A) linked . . . sort independently during meiosis B)homologous . . . are inherited together C) linked . . . do not sort independently during meiosis D) codependent . . . do not sort independently during meiosis

C

How is sex determined in most ants and bees? A) by the Z-W system B) by the size of the sex chromosome C) by the number of chromosomes D) by the X-Y system

C

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

C

Linked genes generally A) reflect a pattern of codominance. B) show incomplete dominance. C) do not follow the laws of independent assortment. D) show pleiotropy.

C

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

C

The alleles of a gene are found at ________ chromosomes. A) the same locus on non-homologous B) different loci on homologous C) the same locus on homologous D) different loci on non-homologous

C

The individual features of all organisms are the result of A)the environment. B) the environment and individual needs. C)genetics and the environment. D) genetics.

C

What is meant by the statement that "male bees are fatherless"? A) The queen bee's mate dies before the male eggs hatch. B) Male bees are produced by budding. C) Male bees develop from unfertilized eggs. D) Male bees don't play a role in the rearing of bee young.

C

Which of the following is an example of incomplete dominance in humans? A. skin color B. sickle-cell disease C. hypercholesterolemia D. ABO blood groups

C

Which of the following statements 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. The presence of a lethal dominant allele causes sterility. 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. Unlike lethal disorders caused by recessive alleles, lethal disorders caused by dominant alleles usually cause the death of the embryo.

C

Which of the following statements regarding prenatal testing is false? A. Ultrasound imaging has no known risk. B. Results from chorionic villus sampling come faster than from amniocentesis. C.Chorionic villus sampling is typically performed later in the pregnancy than amniocentesis. D. Chorionic villus sampling and amniocentesis are usually reserved for pregnancies with higher than usual risks of complications.

C

You conduct a dihybrid cross. A ________ ratio would make you suspect that the genes are linked. A) 3:1 B) 9:3:3:1 C) 12:1:1:4 D) 1:1:1:1

C

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

D

For most sexually reproducing organisms, Mendel's laws A. explain the reasons why certain genes are dominant. B. help us understand the global geographic patterns of genetic disease. C. clarify the phenomenon of incomplete dominance. D. cannot strictly account for the patterns of inheritance of many traits.

D

How many sex chromosomes are in a human gamete? A) three B) two C) four D) one

D

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 A. polygenic inheritance. B. codominance. C. pleiotropy. D. incomplete dominance.

D

Most genetic disorders of humans are caused by A. dominant alleles. B. multiple alleles. C. a mutation that occurs in the egg, sperm, or zygote. D. recessive alleles.

D

Most people afflicted with recessive disorders are born to parents who were A. slightly affected by the disease, showing some but not all of the symptoms. B. subjected to some environmental toxin that caused the disease in their children. C. both affected by the disease. D. not affected at all by the disease.

D

The chromosome theory of inheritance states that A) chromosomes that exhibit mutations are the source of genetic variation. B) the behavior of chromosomes during mitosis accounts for inheritance patterns. C) humans have 46 chromosomes. D) the behavior of chromosomes during meiosis and fertilization accounts for patterns of inheritance.

D

The phenotypic ratio resulting from a dihybrid cross showing independent assortment is expected to be A. 9:1:1:3. B. 3:1. C. 1:2:1. D. 9:3:3:1.

D

The sex chromosome complement of a normal human female is A) XY. B) YY. C) XO. D) XX.

D

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

D

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

D

Which of the following is essentially the opposite of pleiotropy? A) multiple alleles B) codominance C)incomplete dominance D) polygenic inheritance

D

Which of the following statements best represents the theory of pangenesis developed by Hippocrates? A) Offspring inherit the traits of either the mother or the father, but not both. B) Pregnancy is a spontaneous event, and the characteristics of the offspring are determined by the gods. C) Heritable traits are influenced by the environment and the behaviors of the parents. D) 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.

D

Which plants in this figure must all be heterozygous? A) white-flowered plants in the P generation B) purple-flowered plants in the F2 generation C) purple-flowered plants in the P generation D) purple-flowered plants in the F1 generation

D