Bio Ch. 9

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

*Dd* and *Dd*

Which statement about sex determination in the animal kingdom is true? A) Sex in all animals is determined by the presence of one or two sex chromosomes. B) In all animals, sex is determined by environmental factors such as nutritional status. C) In some animals, sex chromosomes determine sex and, in some animals, environmental factors such as temperature determine sex.

*In some animals, sex chromosomes determine sex* and, in some animals, environmental factors such as temperature determine sex.

In giraffes, long necks (N), long legs (L), dark spots (D), and the ability to digest maize (M) are all dominant traits. What possible genotype could a long-necked, short-legged, light-spotted, maize-digesting giraffe have? A) NnllddMM B) NNLLDdMm C) NNllddmm D) nnLLddMM

*Nn*llddMM

Blood samples are taken from the heel of newborn babies to test for a mutation in the PKU gene. Why is this so important? A) PKU inevitably leads to mental retardation, reduced skin pigmentation, and other behavior problems and the family needs to plan for care for the child. B) PKU is lethal in newborns if not treated immediately. C) PKU can be completely treated with dietary management of the amino acid phenylalanine, preventing any negative outcomes in the child, but the diet needs to be started immediately. D) The government must track all cases of PKU to be sure the disease does not spread through the population.

*PKU can be completely treated* with dietary management of the amino acid phenylalanine, preventing any negative outcomes in the child, but the diet needs to be started immediately.

According to this figure, heterozygotes for this form of hypercholesterolemia suffer from the disease because they ________. A) produce an abnormally shaped LDL receptor B) don't produce any LDL receptors C) produce too many LDL receptors D) don't produce enough LDL receptors

*don't* produce *enough* LDL receptors

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

*hetero*zygous for the trait and *able*

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) incomplete dominance B) codominance C) pleiotropy D) polygenic inheritance

*incomplete dominance*

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) dominant B) codominant C) incompletely dominant D) recessive

*incompletely* dominant

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

*linked; do not* sort independently during meiosis

Most 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

*not affected* at all by the disease

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

*recessive* alleles

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 Mendelians? A) 3 black-eyed:1 orange-eyed B) 0 black-eyed:1 orange-eyed C) 1 black-eyed:3 orange-eyed D) 1 black-eyed:0 orange-eyed

0 black-eyed:1 orange-eyed

Justin has type A blood and his wife Brittany has type B blood. Justin's parents both have type AB blood, and Brittany's parents also both have type AB blood. What are the chances that Justin and Brittany's son Theodore has type A blood? A) 100% B) 75% C) 25% D) 0%

0%

Suppose that an elephant with the genotype EEFfggHh reproduces with an elephant with the genotype eeFFGgHh. What is the probability that a baby elephant (called a calf) would have the genotype EeFFGghh? A) 1/16 B) 1/32 C) 1/64 D) 1/256

1/16

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

1/6 + 1/6 = 1/3

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

12:1:1:4

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) 20% B) 25% C) 50% D) 75%

25%

During a summer study abroad program, you traveled to Austria to study genetics at the University of Vienna. While you were there, a momentous discovery was made: Some of Gregor Mendel's original lab books and notes were found to be buried outside of the abbey where he lived. It just so happened that the professor you were working with obtained copies of these notes and enlisted your help to decipher them. You hired a translator to translate Mendel's notes from Czech to English, and using your knowledge of modern genetics (which Mendel did not have!) you were able to construct a partial Punnett square for crosses with peas (shown here). Because the notebook was damaged from being buried for so long, this is the only information that you have regarding a cross that Mendel must have performed. Your professor has tasked you with figuring out more about this experiment. In pea plants, round peas are dominant (R) and shriveled peas are recessive (r), and yellow peas (shown as light gray in the Punnett square) are dominant (Y) and green peas (dark gray) are recessive (y). Using this information and the partial Punnett square shown, what is the phenotypic ratio of the offspring pea plants in this Punnett square? A) 12:1:1:4 B) 9:3:3:1 C) 3:3:1:1 D) 1:1:1:1

3:3:1:1

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. One of Jake and Lucy's kittens mates with another cat that has 18 total toes. What is the probability that one of their offspring would have 18 total toes? A) 100% B) 75% C) 50% D) 0%

50%

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

8%

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

9:3:3:1

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

9:3:3:1

Which statement is true about the determination of sex in humans? A) Any individual without a Y chromosome will always become a female. B) The SRY gene alone can determine maleness. C) An individual may have some genes producing proteins for maleness and other genes producing proteins for femaleness. D) An individual with an X and a Y will always be male.

An individual with an X and a Y will always be male.

Which statement regarding *genotypes and phenotypes 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 homozygous for that trait. C) Alleles are alternate forms of a gene. D) The expressed physical traits of an organism are called its phenotype.

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

In some cats, black coat color (B) is dominant over brown (b) and a striped fur pattern (S) is dominant over a marbled fur pattern (s). You rescued a black striped cat from an animal shelter but could not determine its exact genotype. To do so, you mated the cat with a brown marbled cat. The mating produced 3 brown marbled, 2 brown striped, 2 black marbled, and 3 black striped. Immediately, you concluded the genotype of your rescued cat was ________. A) BBSS. B) BBSs. C) BbSS. D) BbSs.

B*b*S*s*

You are trying to determine if a newborn boy has an X-linked genetic disorder by analyzing a family pedigree. Which of these findings would rule out the X-linked hypothesis? A) All the sons of the baby's grandmother have the disorder. B) There are no females in the pedigree with the disorder. C) Both brothers and sisters have the disorder though neither parent does.

Both brothers and sisters have the disorder though neither parent does.

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

Chorionic villus sampling *is typically performed later in the pregnancy than amniocentesis*.

Which statement is true of the determination of height in humans? A) Height is a situation where a single phenotypic character is determined by the additive effects of three genes. B) Height is determined by 9 separate genes, all of which are codominant. C) Height is determined by variations in more than a hundred genes as well as environmental conditions. D) Height is an example of pleiotropic inheritance.

Height is determined *by variations in more than a hundred genes* as well as environmental conditions.

Which statement 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 the 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.

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.

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. 7) If we use the letter P to represent the polydactyly gene, what is Jake's genotype? A) PP B) Pp C) pp

PP

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

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.

During a summer study abroad program, you traveled to Austria to study genetics at the University of Vienna. While you were there, a momentous discovery was made: Some of Gregor Mendel's original lab books and notes were found to be buried outside of the abbey where he lived. It just so happened that the professor you were working with obtained copies of these notes and enlisted your help to decipher them. You hired a translator to translate Mendel's notes from Czech to English, and using your knowledge of modern genetics (which Mendel did not have!) you were able to construct a partial Punnett square for crosses with peas (shown here). Because the notebook was damaged from being buried for so long, this is the only information that you have regarding a cross that Mendel must have performed. Your professor has tasked you with figuring out more about this experiment. In pea plants, round peas are dominant (R) and shriveled peas are recessive (r), and yellow peas (shown as light gray in the Punnett square) are dominant (Y) and green peas (dark gray) are recessive (y). Using this information and the partial Punnett square shown, what genotype should be listed in the square labeled A? A) RRYY B) RrYy C) rrYy D) RRyy Answer: B

RrYy

During a summer study abroad program, you traveled to Austria to study genetics at the University of Vienna. While you were there, a momentous discovery was made: Some of Gregor Mendel's original lab books and notes were found to be buried outside of the abbey where he lived. It just so happened that the professor you were working with obtained copies of these notes and enlisted your help to decipher them. You hired a translator to translate Mendel's notes from Czech to English, and using your knowledge of modern genetics (which Mendel did not have!) you were able to construct a partial Punnett square for crosses with peas (shown here). Because the notebook was damaged from being buried for so long, this is the only information that you have regarding a cross that Mendel must have performed. Your professor has tasked you with figuring out more about this experiment. In pea plants, round peas are dominant (R) and shriveled peas are recessive (r), and yellow peas (shown as light gray in the Punnett square) are dominant (Y) and green peas (dark gray) are recessive (y). Using this information and the partial Punnett square shown, what were the phenotypes of the parental plants that were used in this cross by Mendel? A) Rryy and RrYy B) Rryy and rrYy C) RRyy and rryy D) RrYy and RrYy

Rryy and RrYy

Which statement regarding *sickle-cell disease is FALSE*? A) Persons who are heterozygous for sickle-cell disease are also resistant to malaria. B) Sickle-cell disease causes white blood cells to be sickle-shaped. C) The multiple symptoms of sickle-cell disease result from the actions of just one allele. D) About 1 in 10 African Americans is a carrier of sickle-cell disease.

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

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

The *hybrid* offspring of a cross are the P*1* generation.

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? A) The gene for color vision is incompletely dominant to the gene for sex determination. B) The gene for color vision is codominant with the gene for sex determination. C) The gene for color vision is found on the X chromosome. D) The gene for color vision is found on the Y chromosome.

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

You prepare a human karyotype. Upon analysis, you find 22 pairs of chromosomes that are each of approximately equal length and also a single pair that has one chromosome longer than the other. What can you conclude from this information? A) The organism that this cell came from is likely a female. B) The organism that this cell came from is likely a male. C) The organism that this cell came from has a genetic disease. D) This cell is likely haploid.

The organism that this cell came from is likely a *male*.

You are trying to determine the linkage map of a series of genes, X, Y, and Z, from Caenorhabditis elegans, a nematode worm commonly used in scientific research. From doing several crossover experiments, you know that the recombination frequency between X and Y is 11.5%, between Y and Z is 13%, and between X and Z is 25%. What is a possible sequence of these genes? A) X-Z-Y B) Y-Z-X C) Z-X-Y D) X-Y-Z

X-Y-Z

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

XX

A testcross is ________. A) a mating between an individual of unknown genotype and an individual homozygous recessive for the trait of interest B) a mating between an individual of unknown genotype and an individual heterozygous 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

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

Research since Mendel's time has established that the law of 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

applies to all *sexually* reproducing organisms

What type of inheritance fits the data in this pedigree? A) sex-linked dominant B) autosomal recessive C) autosomal dominant

autosomal *recessive*

The individual features of all organisms are the result of ________. A) only the genes present B) only the environment in which the organism develops C) both the environment and the needs of the individual D) both the interaction between genetics and the environment

both the *interaction between genetics and the environment*

For most sexually reproducing organisms, Mendel's laws ________. A) cannot strictly account for the patterns of inheritance of many traits B) explain the biological mechanisms behind why certain genes are dominant or recessive C) help us understand the global geographic patterns of genetic disease D) can predict whether offspring will be male or female with 100% accuracy

cannot strictly account for the patterns of inheritance of many traits

The *expression of both alleles for a trait in a heterozygous individual* illustrates ________. A) codominance B) pleiotropy C) polygenic inheritance

codominance

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

crossing over

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

do not follow the laws of independent assortment

A man and his wife are having trouble having a baby. Using modern technologies, the woman's eggs are removed, fertilized with her husband's sperm, and implanted into her uterus. The procedure is successful, and the woman gives birth to a healthy baby boy. After a while, though, they discover that their son is colorblind 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 colorblind, although one grandparent (the woman's father) is also colorblind. As a genetic counselor, you would explain to the parents that ________. A) the eggs must have been accidentally switched, since the baby's blood type has to match one of his parents B) each parent could have contributed one recessive allele, resulting in type O blood C) it is possible for the baby to have type O blood, since type O is inherited through a dominant allele

each parent could have contributed one recessive allele, resulting in type O blood

Shown here is a representation of a portion of a pair of homologous chromosomes. Crossing over would probably be most frequent between ________. A) hair and legs B) hair and eyes C) eyes and legs D) eyes and arms

hair and legs

What is the most likely explanation for the occurrence of an X-linked genetic disorder in the boy at the bottom of the pedigree shown? A) The boy inherited this allele from his father only. B) The boy inherited this allele from his mother only. C) The boy inherited the kind of allele that skips every other generation. D) The boy has a new mutation for the disorder.

he boy has a *new mutation for the disorder*.

Which trait is an *example of incomplete dominance in humans*? A) albinism B) hypercholesterolemia C) skin color D) ABO blood groups

hypercholesterolemia

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

is called a *sex-linked gene*

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

karyotyping; biochemical testing

Sex-linked conditions are more common in men than in women because ________. A) men acquire two copies of the defective gene during fertilization 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) most genes associated with the sex-linked conditions are linked to the Y chromosome, which determines maleness

men need to inherit only *one copy of the recessive allele for the condition to be fully expressed*

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

one

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

one X chromosome and one Y chromosome

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

peas

Blood samples are taken from the heel of newborn babies to test for a mutation in the PKU gene, which, if left untreated and in severe cases, can lead to mental retardation, reduced skin pigmentation, and seizures. Which concept is being illustrated by this example? A) incomplete dominance B) polygenic inheritance C) pleiotropy D) codominance

pleiotropy

Sickle-cell disease is an example of ________. A) pleiotropy B) polygenic inheritance C) a trait with more than two alleles

pleiotropy

The *presence of AB blood type* illustrates the principle of ________. A) incomplete dominance B) codominance C) pleiotropy D) polygenic inheritance

pleiotropy

Which term refers to a *situation where a single phenotypic character is determined by the additive effects of two or more genes*? A) incomplete dominance B) codominance C) pleiotropy D) polygenic inheritance

polygenic inheritance

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

purple-flowered plants in the *F1* generation

During a summer study abroad program, you traveled to Austria to study genetics at the University of Vienna. While you were there, a momentous discovery was made: Some of Gregor Mendel's original lab books and notes were found to be buried outside of the abbey where he lived. It just so happened that the professor you were working with obtained copies of these notes and enlisted your help to decipher them. You hired a translator to translate Mendel's notes from Czech to English, and using your knowledge of modern genetics (which Mendel did not have!) you were able to construct a partial Punnett square for crosses with peas (shown here). Because the notebook was damaged from being buried for so long, this is the only information that you have regarding a cross that Mendel must have performed. Your professor has tasked you with figuring out more about this experiment. In pea plants, round peas are dominant (R) and shriveled peas are recessive (r), and yellow peas (shown as light gray in the Punnett square) are dominant (Y) and green peas (dark gray) are recessive (y). Using this information and the partial Punnett square shown, what phenotype should be in the square labeled B? A) round and yellow B) shriveled and yellow C) shriveled and green D) round and green

round and green

A man and his wife are having trouble having a baby. Using modern technologies, the woman's eggs are removed, fertilized with her husband's sperm, and implanted into her uterus. The procedure is successful, and the woman gives birth to a healthy baby boy. After a while, though, they discover that their son is colorblind 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 colorblind, although one grandparent (the woman's father) is also colorblind. In regard to the baby's color blindness, a sex-linked recessive trait, you explain that ________. A) color blindness often appears randomly, even if neither parent is colorblind B) the baby's father must have a recessive allele for color blindness C) since color blindness is sex-linked, a son can inherit color blindness if his mother has the recessive color blindness allele D) the eggs must have been accidentally switched, since males inherit sex-linked traits only from their fathers

since color blindness is sex-linked, a son can inherit color blindness if his mother has the recessive color blindness allele.

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

the *same* locus on *homo*logous

Maternal inheritance patterns from generation to generation cannot be analyzed by simply studying the X chromosome in the way that paternal inheritance patterns can follow the Y chromosome because ________. A) the X chromosome is too large to analyze effectively B) the X chromosome sometimes exchanges genetic information with the Y chromosome C) the X chromosome is obtained from both the father and the mother D) one X chromosome is deactivated in females

the X chromosome is *obtained from both the father and the mother*

Mendel's law of independent assortment states that ________. A) chromosomes sort independently of each other during mitosis and meiosis B) independent sorting of genes produces polyploid plants under some circumstances C) the allele that a gamete receives for one gene does not influence the allele the gamete receives for another gene D) genes are sorted concurrently during gamete formation

the allele that a gamete receives for one gene does not influence the allele the gamete receives for another gene

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) both of the parents are homozygous for both traits B) the same alleles that control coat color can also cause PRA C) the alleles for color and vision segregate independently during gamete formation

the alleles for color and vision segregate independently during gamete formation

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

the behavior of chromosomes during meiosis and fertilization accounts for patterns of inheritance

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 genes exhibit incomplete dominance over each other B) the frequencies of mutations in the genes C) the frequencies with which the genes are inherited from the mother and from the father D) the frequencies with which the corresponding traits occur together in offspring

the frequencies with which the *corresponding traits occur together in offspring*

DNA kits do not provide information on ________. A) the presence of alleles for certain diseases such as cystic fibrosis B) the likely sex ratio of one's offspring C) the amount of Neanderthal DNA present D) the possible region of one's ancestry

the likely sex ratio of one's offspring

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

the male's *phenotype results entirely from his single X-linked gene*

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) true-breeding

true-breeding