CellBio Chp 9

The scientist Jean Baptiste Lamarck proposed that if an individual acquired a particular characteristic—such as strength from lifting weights—this characteristic would be inherited by the organism's offspring. This same idea is also part of a more ancient idea, the idea of _____.

Mendel's view of the mechanism of heredity was radically different from the prevailing view of the time because he saw heredity working through _____

Two mice are crossed. Matings are carried out between the offspring of these mice to produce "grandchildren" of the original mated pair. In the standard terminology of genetics, the "grandchildren" are the _____.

True-breeding individuals differing in a single character, say a pea plant bearing green seeds and another bearing yellow seeds, are crossed. Assuming that this trait is determined by a single gene that is present in two forms (yellow and green, in this case), how can you tell which allele is dominant and which is recessive?

Mendel was a meticulous experimentalist. One set of crosses he performed to test his idea that a pair of hereditary determinants segregated into gametes was to allow self-fertilization of F2 individuals to produce F3 offspring. What proportion of the purple-flowered F2 individuals did Mendel predict to be true-breeding

An insect that has the genotype EeGGcc will have the same phenotype as an insect with the genotype _____

In an individual of genotype Aa, where are the A and a alleles physically located?

Mendel's principle of independent assortment applies to the _____

Assume that in cattle a spotted coat is dominant to an even coat, short horns are dominant to long horns, and the traits for coat type and horn length assort independently. In a cross between cattle that are each heterozygous for both traits, what proportion of their offspring are expected to have long horns?

You cross two fruit trees. One tree produces lemons with spiky leaves, the other produces limes with smooth leaves. Your F1 generation produces lemons with smooth leaves and spiky leaves. What are the genotypes of the parents? L = lemons; l = limes; S = smooth leaf; s = spiky leaf.

Imagine that long fins in zebrafish is a dominant trait. A breeder wants to set up a breeding program beginning with homozygous dominant long-finned fish. If she obtains a handful of the rare long-finned fish, how can she tell which if any of these are homozygous for the trait?

In Labrador dogs, black coat is dominant to chocolate, normal vision is dominant to progressive retinal atrophy (PRA), and normal hip joint is dominant to hip dysplasia. All these genes assort independently. Two dogs that are heterozygous for alleles of all three genes are crossed. Using rules of probability (not a Punnett square), what is the chance that the first pup born to these dogs will be chocolate, have normal vision, and have normal hip joints

Two normal parents have three normal children: one son and two daughters. Their son and one of their daughters marry and also have normal children. Their second daughter, Mary, marries a man with a rare, recessive blood disorder. They have two children, and both children develop the blood disorder. What were the genotypes of Mary's parents?

Human genetic disorders _____

Why are lethal dominant alleles so much more rare than lethal recessive alleles?

Imagine you're counseling a couple who have undergone carrier screening for Tay-Sachs disease. The man is a carrier, and the woman does not carry the Tay-Sachs allele. How should you advise them?

A large and increasing number of genetic tests are available to prospective parents and children. Even as these testing methods become more and more sophisticated, what is one thing technology will never solve?

Akin to urban legends, there are curious genetics legends—things like eye color being determined by one gene, with a brown eye allele being completely dominant to blue. The problem comes when simple myth meets the complex reality of how eye color and many other traits are transmitted. Why is the inheritance of so many traits difficult to explain using only Mendel's view of genetics?

Hypercholesterolemia is a disorder in which blood cholesterol levels are elevated. The H allele is incompletely dominant to the h allele, with hh homozygotes having extremely high levels of blood cholesterol. A husband and wife are both Hh heterozygotes. What is the chance that their first child will have normal levels of blood cholesterol?

Snapdragons show incomplete dominance in their flowers. A pink snapdragon is crossed with a red snapdragon. What is true about the offspring?

There are over 100 alleles known for the gene associated with cystic fibrosis. With current technology, it is possible to determine exactly which allele or alleles are carried by a person. What is the maximum number of different alleles that any person can carry?

In lentils, the C gene has two different alleles. CSCS homozygotes have spotted seeds, CDCD homozygotes have dotted seeds, and CSCD heterozygotes have seeds with both spots and dots. This indicates that _____.

Two individuals decide to have children. The expected blood group genotypes are 50% of blood type A, and 25% each of blood types AB and B. What genotypes are the parents?

If the gene for seed color that Mendel studied exhibited pleiotropy, how might a green pea be different from a yellow pea?

In breeding pure-breeding large and small strains of mice, you cross individuals of each strain and note that their offspring are intermediate in size. Two models (explanations) to account for this result are (1) that body size in these strains is due to one gene with alleles that show incomplete dominance and (2) that body size is a polygenic trait. How could you distinguish between these models?

Our understanding of the role played by genes in many human characteristics—for example, body size, performance on IQ tests, and personality traits—is advancing rapidly. In this new genetic era, the role of the environment _____.

Which of the following line or lines of evidence support the chromosome theory of inheritance?

In corn, blue kernels are produced by a dominant allele of a coloration gene, and white kernels are produced in individuals homozygous for a recessive allele of the same coloration gene. Another gene has two alleles for shape, with smooth kernels being dominant to wrinkled. A plant heterozygous for both genes is testcrossed (crossed to a homozygous recessive white, wrinkled strain). The testcross offspring consist of the following types: 1,447 blue smooth; 1,436 white wrinkled; 150 blue wrinkled; 145 yellow smooth. Explain the inheritance of the coloration and shape traits.

In Morgan's testcross of a gray-bodied, long-winged heterozygous female Drosophila with a homozygous recessive black-bodied, vestigial-winged male, the following offspring were obtained: 965 gray body, long wing; 944 black body, vestigial wing; 206 gray body, vestigial wing; 185 black body, long wing. Focusing only on the recombinant classes (gray body, vestigial wing and black body, long wing), the numbers of offspring of each type are similar (206 and 185). What accounts for the similar number of offspring of each recombinant phenotype?

Imagine that a mutant strain of Drosophila undergoes crossing over at half the normal rate. How would a genetic map prepared for this mutant differ from a genetic map prepared for a normal (wild type) fly?

The existence of rare XY individuals who are phenotypically normal women was instrumental in learning about human sex determination. Maleness is determined by the SRY gene found on the Y chromosome. How is it possible to be an XY woman

Vitamin D-resistant rickets is an X-linked dominant bone disorder. A man with this form of rickets marries a normal woman. What proportion of the couple's daughters is expected to have vitamin D-resistant rickets?

A woman who is a carrier of hemophilia marries a man affected with hemophilia. What percentage of their sons and daughters are expected to have hemophilia?

Two true-breeding plants are cross-fertilized. Their offspring are then cross-fertilized. What is the name given to this last offspring generation?

DdEe pea plants can produce _____ type(s) of gametes, but a ddee plant can produce _____ type(s) of gametes.

Three characteristics assort independently in one species of insect: Red eyes (R) are dominant to black eyes (r). Blue wings (B) are dominant to white wings (b). Green bodies (G) are dominant to yellow bodies (g). A cross is made between two heterozygous insects (RrBbGg). What is the probability that the offspring will be homozygous dominant for all three characteristics?

Many genetic disorders can be detected before birth. Procedures include _____, which is noninvasive, or _____, which allows the chromosomes of the fetus to be examined. Alternatively, maternal blood samples can be taken and tested for _____ .

After crossing a true-breeding red-flowered snapdragon with a true-breeding white-flowered one, you note that all of your F1 population are pink. This is because _____.

Two parents of mixed ethnicity have twins, one of which is born white and one of which is born black. This is because of _____.

Linked genes are inherited together. This is because linked genes _____

The frequency at which crossing over occurs between two linked genes depends on _____.

Gene Q is an X-linked dominant allele in crustaceans that controls eye color. A cross is performed between two crustaceans: a green-eyed male (XQY) and a green-eyed female (X QX q). What percentage of the offspring have green eyes?

A woman and her male partner have normal color vision. However, her father and her first son are color-blind. What is her genotype? Use C as the gene for color blindness

Previously, it was thought that the blending hypothesis explained inheritance. The blending hypothesis maintained that _____.

The cross-fertilization of two different, but true-breeding, varieties of pea plants will _____.

When applied to Mendel's experiments, the term true-breeding means a self-fertilization of two plants that produces _____.

In a certain plant, the alleles A, B, and C are dominant to the alleles a, b, and C. A plant with the genotype AABbcc will have the same phenotype as the plant with the genotype _____

A child with cystic fibrosis can be born to two parents who do not have the disease. This is because the disease ____

Assume tall (T) is dominant to dwarf (t). If a homozygous dominant true-breeding individual is crossed with a homozygous true-breeding dwarf, the offspring will _____.

Phenylketonuria (PKU) is an autosomal recessive disorder that can lead to mental retardation and seizures. Using P and p to represent the alleles, what is the genotype of a phenylketonuric person?

If a homozygous dominant (AA) is crossed with a homozygous recessive (aa) for a given character, the offspring will be _____.

When you cross two heterozygotes (Aa), the F1 generation will be _____.

In Mendel's monohybrid cross of true-breeding purple-flowered and white-flowered peas, all members of the F1 generation were of the _____ phenotype because their genotype was _____ for the flower-color gene.

Huntington's disease is caused by an autosomal dominant allele. If a heterozygous male were to marry a female not carrying the disease, what percentage of the offspring will have Huntington's?

What is an allele?

Achondroplasia is a common cause of dwarfism and is an autosomal dominant condition. If a male individual has achondroplasia, which statement below must be true?

Homologous pairs of chromosomes frequently _____

An AABb individual is mated with another AABb individual. The possible number of genetically different kinds of offspring is _____.

Pea flowers may be purple (P) or white (p). Pea seeds may be round (R) or wrinkled (r). What proportion of the offspring from the cross PpRr x PpRr will have white flowers and wrinkled seeds?

You have one tree that produces big yellow apples and another tree that produces small red apples. When the two are crossed, you find that half the offspring trees produce big red apples and half produce big yellow apples. What are the genotypes of the parents? A = big apples; a = small apples; R = red apples; r = yellow apples.

A couple who both have the ability to roll their tongues have a son who is also a tongue-roller. Tongue-rolling is a dominant characteristic. The son is curious about whether he is homozygous or heterozygous for tongue-rolling. How could he find out?

Pea plants are tall if they have the genotype TT or Tt, and they are short if they have the genotype tt. A tall plant is crossed with a short plant. Half the offspring are tall, and half are short. This allows us to conclude that the tall plant _____.

The results of a testcross (that is, the offspring of this cross) were 50% phenotypically dominant and 50% phenotypically recessive. The genotype of the phenotypically dominant parent in this cross was _____

What is indicated when a single-character testcross yields offspring in a 1:1 phenotypic ratio?

Suppose we have a pea plant with purple flowers, determined by the dominant allele P. How might you determine whether the plant is homozygous (PP) or heterozygous (Pp)

If each parent can produce 100 genetically distinct gametes, how many genetically distinct offspring can two parents produce

A cross is made between two heterozygous pea plants, and observations are made about three characteristics: flower color, seed color, and seed shape. What is the probability that the offspring will be heterozygous for all three characteristics?

Tay-Sachs disease runs in Rebecca's family. On a family pedigree, she saw a shaded circle. This represented _____

John and Jane are planning a family, but since each has a brother who has sickle-cell disease, they are concerned that their children may develop sickle-cell disease. Neither John, Jane, nor their respective parents have the disease. They consult a genetic counselor who tells them that _____.

When two average-height parents give birth to a child exhibiting achondroplastic dwarfism, it is most likely due to a new mutation. This is because _____.

Cystic fibrosis, which is usually lethal before the age of reproduction, is a homozygous recessive trait. Even though people with the disease rarely reproduce, cases continue to arise because _____.

It is far more common to find human genetic disease caused by _____ alleles than by _____ alleles because _____.

Michelle and Keith are apparently normal, but their daughter was born with alkaptonuria, an inherited metabolic disorder that causes urine to turn black when exposed to air. If alkaptonuria is like most other human hereditary disorders, the probability of their next child being born with alkaptonuria is _____.

Huntington's disease is an example of a genetic disorder caused by _____

Several inherited disorders are much more common in close-knit religious communities, such as the Amish, than in the general population. This is at least partly due to the fact that _____

Fetal cells may be removed along with fluid from the womb by a process known as _____

The test that is used to determine whether someone possesses a potentially harmful recessive allele is referred to as _____ testing

A red bull is crossed with a white cow and all of the offspring are roan, a shade between red and white. This is an example of genes that are _____

Flower color in snapdragons is an example of incomplete dominance. If a red-flowered plant is crossed with a white-flowered plant, the F1 generation has pink flowers. If a pink-flowered plant is crossed with a pink-flowered plant, the progeny plants will be _____

A male who is homozygous recessive for hypercholesterolemia marries a woman is homozygous dominant. What percentage of their children will have higher than normal blood cholestero

A man who has type B blood and a woman who has type A blood could have children of which of the following phenotypes?

Two individuals have children with A and B blood types. What are the blood types of the parents?

If one parent is blood type AB and the other is type O, what fraction of their offspring will be blood type A?

A woman with type O blood is expecting a child. Her husband is type A. Both the woman's father and her husband's father had type B blood. What is the probability that the child will have type O blood

A single allele that controls more than one character is said to be _____

In people with sickle-cell disease, the red blood cells break down, clump, and clog the blood vessels. The blood vessels and the broken cells accumulate in the spleen. Among other things, this leads to physical weakness, heart failure, pain, and brain damage. Such a suite of symptoms can be explained by _____.

The inheritance of height and weight can best be described as _____

Two identical twins are raised in different environments. They possess _____ genotypes and _____ phenotypes.

Seeds from a single sexually reproducing plant are harvested and later planted under identical conditions. What results should be expected

If two genes are linked, _____.

If hair color, eye color, and the presence or absence of freckles were consistently inherited together, the best explanation would be that ____

If the two characteristics that Mendel looked at in his dihybrid cross of smooth yellow peas with wrinkled green peas had been controlled by genes that were located close together on the same chromosome, then the F2 generation _____.

In a particular species of mammal, black hair (B) is dominant to green hair (b), and red eyes (R) are dominant to white eyes (r). When a BbRr individual is mated with a bbrr individual, offspring are produced in a ratio of 5 black hair and red eyes : 5 green hair and white eyes : 1 black hair and white eyes : 1 green hair and red eyes. Which of these explanations accounts for this ratio?

The following distribution of offspring was observed: blue wings, green eyes 1,070 blue wings, black eyes 177 red wings, green eyes 180 red wings, black eyes 1,072 In a particular species of mammal, blue wings (B) are dominant to red wings (b), and green eyes (G) are dominant to black eyes (g). Based on these data, what is the recombination frequency?

Sturtevant's genetic mapping _____

The crossover percentage between two different genes is _____

The Y chromosomes of mammals contain genes that code for _____.

Gene R is an X-linked recessive allele in fruit flies that controls wing formation. A cross is performed between two fruit flies where the male is XRY and the female is XRXr. What percentage of the offspring are female with abnormal wing development?

Hemophilia appears rarely in females. This is because _____

We can make connections to our ancestry by analyzing the _____ in males