Practice Questions Chapter 2

A plant that produces wrinkled, green seeds was mated to a plant that produces phenotypically round, yellow seeds. In the F1 generation, half of the plants produced round, yellow seeds and the other half produced round, green seeds. The round, yellow F1 seeds were planted and those plants were allowed to self-fertilize. In the F2 generation what fraction of the seeds will be genotypically identical to the plants of the parental generation? Multiple Choice 3/16 1/16 1/4 9/16

3/16

A heterozygous tall pea plant is allowed to self-fertilize. The resulting F1 progeny are 25% homozygous tall, 50% heterozygous tall and 25% dwarf. If all of the F1 plants are allowed to self-fertilize, what percentage of the F2 progeny are dwarf? Multiple Choice 25% 37.5% 50% 75%

37.5

Segregation of the alleles means that a gamete has a ___% chance of getting a particular allele.

50

Look at the progeny from the cross of TtYy x TtYy. If you had 1,008 progeny, how many would be expected to be short and to have green seeds? Multiple Choice 63 16 1008 189

63 Only 1/16 of the progeny will be expected to be short with green seeds. 1008/16 is 63.

What is the probability individual III-6 is heterozygous?

66%

Two plants heterozygous at the genes controlling height and seed color are crossed. Height is controlled by a gene with two alleles: T is the tall allele and t is the short allele. Seed color is determined by two alleles: Y codes for yellow seeds and y for green seeds. Label each square with the correct genotype. Each label may be used more than once.

9:3:3:1

The number of degrees of freedom for a test cross of an Ss/Rr individual would be __

3

Look at the progeny from the cross of TtYy x TtYy. How many phenotypic classes were expected in the resulting progeny? Multiple Choice 1 9 16 4

4

Probability theory can be applied to inheritance since each gamete will have an _ chance of containing any one allele or allelic combination.

equal

The Law of Segregation means that the number of gametes with one allele should be ___ the number of gametes with the other allele.

equal to

A plant that produces wrinkled, green seeds was mated to a plant that produces phenotypically round, yellow seeds. In the F1 generation, half of the plants produced round, yellow seeds and the other half produced round, green seeds. What was the genotype of the parental plant that produced round, yellow seeds? Multiple Choice RRYy RRYY RrYY RrYy

RRYy

The recessive alleles that Mendel studied were most likely the result of ___ of function mutations.

loss

The Law of Independent Assortment applies to meiosis in both __

males and females

An allele that produces an enzyme that has __ would be an example of an allele with a loss-of-function mutation.

no activity

The chi square test does __ a hypothesis, but it tests for the probability that the differences between the observed and expected differ by random chance.

not prove

Due to the limitations of studying humans, investigators rely on __ analysis.

pedigree

The Law of Segregation allows for the prediction of alleleic combinations in the progeny based on ___.

probability

The chance that an outcome will occur in the future is called the outcome's __.

probability

Due to the Law of Independent Assortment the probability of different alleleic combinations being present in a gamete is calculated by the ___ of the frequecies of those alleles.

product

According to the Law of Segregation different alleles will ___ segregate into different gametes.

randomly

If a chi square value exceeds the appropriate p value the null hypothesis is usually __.

rejected

You crossed a plant with wrinkled, yellow seeds to a plant with round, green seeds. In the F1 generation you observed that all of the progeny had round, yellow seeds. What were the genotypes of the parental plants? Multiple Choice rrYY and RRyy rrYY and Rryy rrYy and RRyy rrYy and Rryy

rrYY and RRyy

Mendel's work was critical for a number of reasons but what differentiated his work the most was Multiple Choice that he used peas. that he applied statistical analyses to his results. that he was a priest. that he kept careful records of what he did

that he applied statistical analyses to his results.

Probability is the number of times a particular outcome occurs divided by the __

total number of possible outcomes.

The Law of Indepdent Assortment is based on Mendel's experiments with ___

two factors.

In a pedigree a consanguinous mating is diagrammed as __ between a male and a female.

two horizontal bars

The binomial equation can be used to determine the probability of the __ combination of events occurring.

unordered

The central dogma of biology is that DNA produces RNA which produces protein. An allele that does not produce RNA ___ therefore be an allele that has a loss-of-function mutation.

would

The symbol for an unaffected female is an __

open circle

An individual of indeterminate sex is represented by a ___ in a pedigree.

diamond

complete table. On vertical column: dihybrid, test, monohybrid on horizontal table: genotypes of parents, phenotypic ratio, genotypic ration

dihybrid: SsRrx SsRr, 9:3:3:1, 1:1:1:1:2:2:2:2:4 test cross: SsRrxssrr, 1:1:1:1, 1:1:1:1 monohybrid: Ss x Ss, 3:1, 1:2:1

The most likely reason that a dominant phenotype is seen in the first filial generation of Mendel's experiments is that the __ allele produces enough functional protein for normal development.

dominant

Loss-of-function mutations help to discover a gene's __.

function

If two people who are heterozygous for the PKU allele have a child with PKU, what is the likelihood their next child will have PKU? Multiple Choice 75% 100% 25% 50%

25%

A p value of __ means that there is a 5% chance of obtaining the listed chi square value at the different degrees of freedom.

0.05

Suppose that we are dealing with four genes, each gene consisting of a dominant allele (capital letter) and a recessive allele (small case letter). If the cross CcMmLlPP X CCmmLlpp is made, what is the probability of obtaining an individual who is CcmmLLPp? Multiple Choice 1/2 1/4 1/8 1/16

1/16

When a heterozygous plant with round seeds is mated to a plant with wrinkled seeds what fraction of the progeny are heterozygous? Multiple Choice 2/3 1/4 1/2 3/4

1/2

When a heterozygous plant with round seeds is mated to a plant with wrinkled seeds what fraction of the progeny are homozygous? Multiple Choice 1/4 3/4 2/3 1/2

1/2

Cystic fibrosis is an autosomal recessive disorder that affects lung function in humans. If a couple, who are both unaffected, have an affected child, what is the probability their next child will be an affected girl? Multiple Choice 1/2 1/4 1/8 1/16

1/8

What is the probability individual II-4 is heterozygous?

100%

f two heterozygous plants with round seeds are mated, what fraction of the progeny with round seeds are genotypically heterozygous? Multiple Choice 3/4 1/2 2/3 1/4

2/3

If 100 different ova from an Ss/Rr individual are genotyped the number of ova that would have the SR allelic combination would be predicted to be ___.

25

A heterozygous tall pea plant is allowed to self-fertilize. The resulting F1 progeny are 25% homozygous tall, 50% heterozygous tall and 25% dwarf. If all of the F1 plants are allowed to self-fertilize, what percentage of the F2 progeny are heterozygous tall? Multiple Choice 25% 37.5% 50% 75%

25%

If two people who are both carriers for PKU have a child, what is the likelihood the child will be born with PKU? Multiple Choice 75% 100% 25% 50%

25%

A mating of an Ss individual to an individual that is SS has a probability of producing an SS offspring of __%

50

Cystic fibrosis is an autosomal recessive disorder that affects lung function in humans. A man and a woman are both unaffected heterozygous carriers of a cystic fibrosis gene. If the couple has two children, what is the probability that their first child will be unaffected and their second child will be unaffected? Multiple Choice 6.25% 18.75% 37.5% 56.25%

56.25% There are three possible scenarios that would satisfy the requirements of this question: 1) girl, girl, boy, 2) girl, boy, girl or 3) boy, girl, girl. The likelihood of each individual possibility is 1/2*1/2*1/2 or 1/8. Therefore using the addition rule, the likelihood that any of these three possibilities will occur is 3/8.

How many genotypic classes were expected in the resulting progeny? Multiple Choice 12 9 16 4

9 There are nine different combinations of alleles present. Some of the combinations occur more than once in the Punnett square and in the progeny.

The trait depicted in the pedigree shown is most likely inherited in what manner? I-1 affected male mates with I-2 unaffected female. II-1 unaffected male, II-2 unaffected female, II-3 affected male, II-4 affected female mates with II-5 unaffected male. III-3 unaffected female, III-4 unaffected male, III-5 affected female. III-2 affected male mates with III-1 unaffected female. IV-1 unaffected male, IV-2 unaffected female, IV-3 affected female. Autosomal recessive Autosomal dominant X linked recessive X linked dominant

Autosomal dominant The trait is always passed from affected individuals to their progeny which suggests a dominant allele. This is not the case for inherited recessive traits. Since I-1 passed it to his son II-3 we know it is not X-linked since a son does not inherit an X from his father. Additionally since females show this trait, it cannot be Y-linked.

You are a researcher examining the expression pattern of a wobbly fly phenotype. You have flies that fly straight and those having a wobble flight. When you cross a straight flying strain with a strain showing a wobble flight, all the F1 flies fly straight. In the F2 generation, you get 762 straight flying flies and 238 wobbly flies. Your null hypothesis is that one gene controls flight patterns and that straight is dominant to wobbly. Use chi square analysis to test your hypothesis. What is your chi square number? Do you reject or fail to reject the null hypothesis? Use the table listed below to help answer the question. Chi square = 0.768, reject Chi square = 0.768, fail to reject Chi square = 0.192, reject Chi square = 0.192, fail to reject

Chi square = 0.768, fail to reject

In tomatoes, yellow flowers (Y) are dominant to white flowers (y) and round fruit (R) is dominant to oblong fruit (r). You cross a heterozygous yellow round plant with a plant with white flowers and oblong fruit. You get the following progeny: 238 yellow round 210 yellow oblong 270 white round 282 white oblong Formulate a null hypothesis and performing a Chi-Square analysis on it, what chi-square number would you obtain. Based upon this number, would you reject or not reject your null hypothesis?. Use the table listed below. Chi square=12.7, reject Chi square=12.7, fail to reject Chi square=987, reject Chi square=987, fail to reject

Chi square=12.7, reject

Pedigree characteristic of dominant and recessive allele when it comes to allele on X chromosome

Dominant: If allele is on the X chromosome, affected individuals are typically male and female Recessive: Affected individuals are almost exclusively males

Both members of a couple are heterozygous for an autosomal recessive disorder called PKU. Affected individuals cannot properly process phenylalanine. Use the Punnett square to diagram the expected progeny from these two people.

Pp X Pp 1:2:1 PP: Pp: pp

T or F: In Mendel's Law of Segregation, the two factors for a trait wind up in separate gametes and randomly unite at fertilization.

T

Two phenotypically tall heterozygous pea plants are crossed to one another. A phenotypically tall F1 progeny plant is randomly chosen and mated to a phenotypically dwarf pea plant. If some of the F2 offspring from this mating are phenotypically dwarf, what is the genotype of the randomly chosen F1 parent plant? Multiple Choice TT tt Tt

Tt

Look at the pedigree shown. What is the most likely pattern of inheritance for this trait? I-1 affected male mates with I-2 unaffected female. Have II-2 unaffected female, II-3 affected male, and II-4 unaffected female. II-1 unaffected male mates with offspring of above II-2 unaffected female. Offspring: III-1 unaffected female, III-2 unaffected male, and III-3 unaffected female. II-4 mates with II-5 unaffected male. Offspring: III-4 affected male, III-5 unaffected female, III-6 unaffected male, and III-7 affected female. III-3 and III-4 mate. Offspring: IV-1 affected female, IV-2 unaffected female, IV-3 unaffected female.

autosomal recessive Since unaffected individuals can have affected children, it likely not a dominant trait. There is male to male transmission which suggests it is not X-linked. The most likely mode of inheritance is therefore autosomal recessive. Unaffected individuals who have an affected child are likely heterozygous.

The symbol used in a pedigreee for an affected male is a __

closed square.

One type of error that can occur with the chi square test is the acceptance of the null hypothesis when it is __.

false

Mendel's Law of Independent Assortment states that two different ___ will be randomly assorted into the gametes.

genes