Bsc1005 BIO Chapter 7

Distinguish between the genotype and a phenotype of a given genetic trait Indicate whether each of the following represents a genotype or phenotype: hairy knuckles

phenotype

A female fern plant is heterozygous for a gene related to photosynthesis (Pp). Select all of the different possible genotypes that her eggs could possess. a. Pp b. p c. PP d. P e. pp

b, d

Distinguish between the genotype and a phenotype of a given genetic trait Indicate whether each of the following represents a genotype or phenotype: A-positive blood type

phenotype

Two cats are both heterozygous for hair length, Ll, and heterozygous for white hair, Ww. Short hair and white hair are dominant to long hair and colored hair, respectively. What are the odds that the pair's offspring would show the following phenotypes? long, white hair

3/16

Distinguish between the genotype and a phenotype of a given genetic trait Indicate whether each of the following represents a genotype or phenotype: Hh alleles

genotype

Distinguish between the genotype and a phenotype of a given genetic trait Indicate whether each of the following represents a genotype or phenotype: homozygous recessive

genotype

Describe the importance of Gregor Mendel's experiments to our understanding of inheritance. Illustrations of a purple-flowered pea plant and a white-flowered pea plant.In one experiment, Mendel crossed pea plants with purple flowers and pea plants with white flowers. The offspring of this cross all had purple flowers. Which statement best explains this pattern?

If one of the parents is homozygous dominant for a trait, all of the offspring from that parent will display the dominant phenotype, regardless of genotype of the mate.

Mendel's breeding experiments with pea plants indicate that alleles of a gene separate during

Meiosis

Which of the following traits are Mendelian and which show more complex patterns of inheritance? yellow versus green pea color in pea plants

Mendelian

Most traits in humans are controlled by the action of multiple genes. These traits are referred to as

Polygenic

T or F: Tongue rolling was thought to be an example of a human trait controlled by a single gene, but we now know that identical twins, who share 100 percent of their DNA sequences, will only share the tongue-rolling trait 70 percent of the time. This indicates that tongue rolling may also be controlled by the environment.

T

Gregor Mendel described several traits in pea plants in which a dominant trait masked a recessive trait. Two such traits were plant height (T = tall, t = short) and seed shape (R = round, r = wrinkled). Match each genotype below with its expected phenotype. tall and round

TTRR, TTRr, TtRr

Gregor Mendel described several traits in pea plants in which a dominant trait masked a recessive trait. Two such traits were plant height (T = tall, t = short) and seed shape (R = round, r = wrinkled). Match each genotype below with its expected phenotype. tall and wrinkled

TTrr, Ttrr

In a particular plant, two genes control height and flower color. Tall height (T) is dominant to short height (t). Yellow flowers (Y) are dominant to white flowers (y). A tall, yellow flowered plant is mated with a short, white-flowered plant. What are the genotypes of the plants involved in this cross?

T_Y_ x ttyy

Two pea plants that are true-breeding for recessive white flowers are mated and their offspring analyzed. Which of the following statements about this situation is true?

The gametes produced by the offspring will carry one allele for this gene.

An allele is a. A version of a gene b. A trait that can affected by the external environment c. Always codominant to its counterpart in another chromsome d. The result of a change in phenotype

a

If two different alleles for the same trait have an equal effect on the phenotype, the alleles are a. codominant b. recessive c. epistatic d. incompletely dominant

a

Put the potential offspring genotypes in order from highest expected frequency to lowest expected frequency for a cross in which both parents have the RrTt genotype. a. RrTt rrTt RRtt b. RrTt RRtt rrTt c. rrTt RRtt RrTt

a

Which of the following contributions has Gregor Mendel made toward our understanding of genetics and inheritance? a. Different traits are inherited independently of one another. b. Most traits in humans are influenced by multiple genes. c. DNA is the genetic material. d. Each gamete carries only one of the two copies of the parent's alleles.

a, d

If you compare a sperm cell in a human to a skin cell from the same individual, which of the following differences would you expect to find? a. The sperm cell would contain four alleles for a given gene; the skin cell would contain two alleles. b. The sperm cell would contain only one allele for a given gene; the skin cell would contain two alleles c. Both sperm and skin cells may carry different alleles for an individual gene d. Both sperm and skin cells would contain 46 chromosomes found as homologous pairs.

b

In 4 o'clock flowers, flower color is controlled by a single gene with two alleles. The R allele produces red flower color, and the W allele produces white flower color. These alleles display incomplete dominance, and when both alleles are present, the flowers appear pink. Remember, when dealing with incomplete dominance, only capitals are used for the two traits because neither allele exerts dominance over the other. Match each of the following genotypes to the correct color of flowers. white flowers a. RR b. Rw c. WW d. homozygous

c, d

Which of the following traits are Mendelian and which show more complex patterns of inheritance? body size in humans

complex

In pea plants, height is controlled by a single gene and the tall allele (T) is dominant to the short allele (t). You find a tall pea plant in your yard and cross it with a short pea plant. It gives rise to 43 tall offspring and 35 short offspring. What is the genotype of the tall parent plant? a. tt b. TT c. tT d. Tt

d

Which of the following statements regarding genes is NOT true? a. Genes are located on chromosomes b. Genes consist of a long sequence of DNA c. Genes are the basic unit of information affecting a genetic trait d. In sexually reproducing species, each cell contains a single copy of every gene

d

One challenge of studying genetics, even in dogs, is that many traits do not follow Mendelian rules. For instance, coat color can be affected by multiple genes, while in other cases, multiple traits, such as the shape of a dog's head and limbs, can be controlled by a single gene. For each example below, determine if the trait is pleiotropic, polygenic, or environmental. The sex of an alligator is determined by the temperature of the soil in which the eggs are buried.

environmental

The chance of a parent passing on a given allele to a child _____________ each time he or she has another child.

is the same

Occasionally, a gamete is formed that contains both alleles of a gene instead of one. The result is the presence of three alleles of a gene after fertilization. Which of Mendel's laws would this gamete violate, and when during meiosis would the gamete form?

law of segregation, meiosis 1

In modern terms, Mendel's law of segregation states that each gamete formed through meiosis receives a [single or two] allele of each gene, while the law of independent assortment states that the alleles in those gametes are chosen at random.

single

Gregor Mendel described several traits in pea plants in which a dominant trait masked a recessive trait. Two such traits were plant height (T = tall, t = short) and seed shape (R = round, r = wrinkled). Match each genotype below with its expected phenotype. short and wrinkled

ttrr

While studying the outcomes of reproduction in pea plants, Gregor Mendel found that each individual carries _________ copy/copies of the allele for each trait and that one is/are passed on to each offspring. When studying inheritance of two different traits, Mendel found that the patterns of inheritance of one trait has no effect on the patterns of inheritance of another trait. This concept is now called the law of independent assortment.

two

In Labrador dogs, coat color is controlled by the genotypes of two genes. In one gene, the dominant allele, B, produces black fur, and the recessive allele, b, produces brown fur. However, if a second gene possesses two recessive alleles, ee, the dog produces yellow fur, regardless of the genotype of the first gene. If two dogs that are heterozygous for both genes, BbEe mated, what would be the frequency of the three phenotypes, black, brown, and yellow?

yellow: 4/16 black: 9/16 brown: 3/16

If both a father and a mother have a good sense of humor, they should expect a maximum of 25% chance that they would have an offspring without a good sense of humor.

F

In 4 o'clock flowers, flower color is controlled by a single gene with two alleles. The R allele produces red flower color, and the W allele produces white flower color. These alleles display incomplete dominance, and when both alleles are present, the flowers appear pink. Remember, when dealing with incomplete dominance, only capitals are used for the two traits because neither allele exerts dominance over the other. Match each of the following genotypes to the correct color of flowers. pink flowers a. WW b. RW c. homozygous d. heterozygous e. WR

b, d, e

A brown mouse is repeatedly crossed with a white mouse and produces 43 offspring, all of which are brown. Assuming that mouse hair color is a Mendelian trait (dominant allele = B), drag the correct genotype to each parent mouse: white mouse

bb

BIO cpt2,5

starred

T or F: Two blue-eyed parents can produce a brown-eyed offspring. Blue eyes are recessive

F (If two parents display the recessive trait, than they both must be homozygous recessive and neither would possess any dominant alleles to pass to their offspring.)

If a person has one copy of each of two different alleles for a given gene, the person is ________ for that trait. Select one: a. true-breeding b. recessive c. homozygous d. heterozygous

d

One challenge of studying genetics, even in dogs, is that many traits do not follow Mendelian rules. For instance, coat color can be affected by multiple genes, while in other cases, multiple traits, such as the shape of a dog's head and limbs, can be controlled by a single gene. For each example below, determine if the trait is pleiotropic, polygenic, or environmental. Eye color is a function of the genes responsible for melanin production and the genes controlling the structure of the iris.

polygenic

In cattle, the allele that causes horns to grow is recessive. Another recessive allele causes the cows to grow abnormally large and muscular. These muscular cows are often called Belgian blue cows. If a cow that is heterozygous for both the horn and Belgian blue trait genes passes on the allele for growing horns to an offspring, what are the odds that the parent cow also passes on the allele for becoming very muscular to that offspring?

50%

T or F: Most traits in humans display Mendelian inheritance.

F

A recent study found that at least 180 different genes seem to be correlated with height in humans, which is partly why height is a continuous trait. If we imagine a much simpler scenario in which only 10 genes control height, and each of these genes displays simple Mendelian inheritance (i.e., there are only two alleles, tall and short, and tall is dominant to short) and shows equal contribution to height, how many different possible genetic height phenotypes would there be in humans?

Since each gene only has two variants, tall or short, and each offers an equal contribution to height, the phenotypic options range from having 0 tall alleles to having 10 tall alleles. This would give us a total of 11 different possible phenotypes for height.

In humans, ear wax might be controlled by a single gene showing Mendelian inheritance, where the two phenotypes are wet ear wax and dry ear wax, and the wet ear wax trait is dominant to the dry ear wax trait. Interested in understanding this trait, you study families and compile the following data.

Since no pairs of parents with dry ear wax produced an offspring with wet earwax, this trait is likely to be governed by a single gene.

Tess's sister is known to carry an allele for a single-gene recessive genetic disorder that is fatal in very early life. Tess's mother was tested for the allele and found not to carry it. What are the odds that Tess is a carrier for the allele?

Since the alleles that are passed on are random, Tess has a 1/2 (or 50%) chance of carrying the allele.

T or F: A single gene trait with two alleles that show incomplete dominance should possess the same number of possible genotypes and phenotypes.

T

Two cats are both heterozygous for hair length, Ll, and heterozygous for white hair, Ww. Short hair and white hair are dominant to long hair and colored hair, respectively. What are the odds that the pair's offspring would show the following phenotypes? long, colored hair

1/16

If the height of pea plants is controlled by a single gene, where the tall allele, T, is dominant to the short allele, t, how many different possible phenotypes of height would exist in total?

2 (Since there is only one dominant and one recessive allele in this population, individuals of this pea plant could only either be tall (TT or Tt) or short (tt).)

In humans, photic sneezing (sneezing when exposed to sunlight) and wet ear wax are both the result of dominant alleles, P and E, respectively. If a woman who is unaffected by photic sneezing but is heterozygous for wet ear wax marries a man who is heterozygous for photic sneezing but has dry ear wax, what percentage of their children would likely both sneeze when exposed to sunlight and have dry ear wax?

25%

Two cats are both heterozygous for hair length, Ll, and heterozygous for white hair, Ww. Short hair and white hair are dominant to long hair and colored hair, respectively. What are the odds that the pair's offspring would show the following phenotypes? short, colored hair

3/16

The human ABO blood type trait displays four phenotypes: A, B, AB, and O. It is controlled by a single gene which has three possible alleles: A, B, and O. The A and B alleles are codominant, and the O allele is recessive to both A and B. How many different possible genotypes exist for this gene?

6 (AA, AO, BB, BO, AB, and OO are all possible genotypes.)

Two cats are both heterozygous for hair length, Ll, and heterozygous for white hair, Ww. Short hair and white hair are dominant to long hair and colored hair, respectively. What are the odds that the pair's offspring would show the following phenotypes? short, white hair

9/16

Which of the following is an example of incomplete dominance?

A heterozygote cat has a medium-sized body instead of being either large or small.

A brown mouse is repeatedly crossed with a white mouse and produces 43 offspring, all of which are brown. Assuming that mouse hair color is a Mendelian trait (dominant allele = B), drag the correct genotype to each parent mouse: brown mouse

BB

T or F: When a gene possesses both dominant and recessive alleles, there are usually more possible phenotypes than genotypes.

F

T or F: Mendel understood that genetic information was carried on material elements within the cell.

F

Which of the following statements explains how genetically identical plant clones can exhibit dramatic phenotypic variation? a.Environmental conditions under which plants are grown can cause variations in phenotypes. b.Plants undergo mutations to adapt to temperature extremes. c.Plants are able to shut off genes that are not adaptive in their current environment. d.Genetically identical plants cannot have different phenotypes

a

In rats, offspring of larger mothers tend to be larger than offspring of smaller mothers, even when fed the same diet and raised apart from their mothers. When fed higher calorie diets, rats tend to be larger than rats fed lower calorie diets, even when they are offspring of the same mother. These two experimental results suggest that rat body size is influenced by which factors? a. the environment b. alleles c. pleiotropy d. epistasis

a, b

In 4 o'clock flowers, flower color is controlled by a single gene with two alleles. The R allele produces red flower color, and the W allele produces white flower color. These alleles display incomplete dominance, and when both alleles are present, the flowers appear pink. Remember, when dealing with incomplete dominance, only capitals are used for the two traits because neither allele exerts dominance over the other. Match each of the following genotypes to the correct color of flowers. red flowers a. RR b. rW c. homozygous d. WR

a, c

Two pea plants are crossed to make 1,000 offspring. All offspring possess long pods and round peas. Long pods (L) are dominant to short pods (l), and round peas are dominant (R) to wrinkled peas (r). Which of the following are possible genotypes of the parent plants? a. LLRR × llrr b. LLRr × LlRr c. LLrr × llRR d. Llrr × llrr

a, c

Which of the following describe conclusions drawn by Gregor Mendel? a. Dominant traits are capable of masking the phenotype of recessive traits. b. An organism's phenotype is determined by genes located on chromosomes. c. The alleles responsible for a trait are separated and passed down to the following generation. d. Some traits are complex and controlled by many different genes.

a, c

Two people of medium skin tone have five children, each with a different skin tone ranging from very pale to very dark. Most of the children's skin becomes a little bit darker after exposure to the sun. Judging from this information, skin tone is probably what? a. influenced by the environment b. a pleiotropic trait c. a Mendelian trait d. a polygenic trait

a, d

A pea plant that is heterozygous for the flower color gene makes gametes. What is the probability that a specific gamete contains the recessive allele for flower color? Select one: a. 25 percent b. 50 percent c. 75 percent d. 100 percent

b

In pea plants, the tall allele (T) is dominant to the short allele (t) and the yellow pea allele (Y) is dominant to the green pea allele (y). In a cross between a TTYy pea and a ttyy pea, what are the odds that the offspring will be tall and have green peas? a. 1/4 b. 1/2 c. 3/4

b

When geneticists first studied eye color, it was suggested that the "blue-eyed" trait was caused by a single recessive allele. Further study indicated that, while rare, blue-eyed parents could have a brown-eyed child. Which of the following statements best describes this trait and the reason for its occurrence? a. It is a complex trait because the allele has mutated. b. It is a complex trait because the rules of dominance are not followed. c. It is a Mendelian trait because there is a 3:1 chance of the offspring displaying the dominant trait. d. It is a Mendelian trait because the alleles are following the laws of segregation and independent assortment

b

Which of the following statements is NOT true? a. Two organisms with the same phenotype may have different genotypes b. Two organisms with the same genotype are homozygous c. A heterozygous organism may have the same phenotype as a homozygous organism d. A heterozygous organism has fewer alleles for a given gene than a homozygous organism

b

A trait's genotype is the combination of alleles that are present at the gene, and a trait's phenotype is the outward expression of the trait. When there are two alleles for a gene, one dominant and one recessive, the heterozygous genotype shows the same phenotype as the homozygous dominant genotype.

break down

f two chickens with the genotypes Aarr and AARR are crossed, what are the possible genotypes of their offspring? Correct Answer(s) AARr AaRr Incorrect Answer(s) AaRR aaRr Aarr

break down

Consider a gene with two alleles that show complete dominance. When a homozygous recessive individual (qq) is crossed with a heterozygous individual (Qq) they have a 50 percent chance of producing a homozygous recessive offspring. The next time these two individuals breed, what are the chances that they will once again have a homozygous recessive progeny? Select one: a. 0 percent b. 25 percent c. 50 percent d. 75 percent

c

Which of the following is true for mutations a. Mutations will affect the genotype without affecting the phenotype b. Mutations will affect the phenotype without affecting the genotype c. Mutations will affect the genotype, which may affect the phenotype d. Mutations will affect the phenotype, which may affect the genotype

c

Which of the following statements regarding genes is true? a. Genes are located within mitochondria. b. Genes are proteins that carry information. c. Genes are the basic units of information affecting a genetic trait. d. In humans, each cell contains four copies of every gene.

c

A great deal of the risk of many human diseases, such as coronary heart disease and type 2 diabetes, is dependent upon lifestyle choices. Which word correctly describes what this indicates about the patterns of inheritance of these diseases?

complex

Which of the following traits are Mendelian and which show more complex patterns of inheritance? coat color in Labrador dogs

complex

Which of the following traits are Mendelian and which show more complex patterns of inheritance? intelligence in humans

complex

Being able to use a Punnett square to track the pattern of inheritance in a two-characteristic cross (for example, pea seed color and seed shape) demonstrates Mendel's idea of Select one: a. allele segregation. b. blending inheritance. c. environmental influences on genes. d. independent assortment.

d

In Mendel's model of inheritance, what he described as units of inheritance we now refer to as:

gene

The fur color of Siamese cats is partly controlled by temperature. Where their skin is relatively cool, like their ears, their fur grows dark, and where their skin is warmer, like their torso, their fur grows white. In this example, temperature is affecting what aspect of the Siamese cat?

phenotype (outward appearance is changed)

One challenge of studying genetics, even in dogs, is that many traits do not follow Mendelian rules. For instance, coat color can be affected by multiple genes, while in other cases, multiple traits, such as the shape of a dog's head and limbs, can be controlled by a single gene. For each example below, determine if the trait is pleiotropic, polygenic, or environmental. People carrying the gene for sickle cell anemia can also suffer from vision loss.

pleiotropic

Even in simple Mendelian genetics, an offspring's traits can be hard to predict. For example, two parents that do not exhibit the sickle-cell anemia trait can produce an offspring with sickle-cell anemia. This indicates that the sickle-cell trait must be what kind of trait?

recessive