Introduction to Genetic Analysis

Anthony J. F. Griffiths, Susan R. Wessler, Sean B. Carroll

Chapter 3

Independent Assortment of Genes - all with Video Answers

Educators

Chapter Questions

Problem 1

Using Table $3-1,$ answer the following questions about probability values (see p. 97 ):
a. If $x^{2}$ is calculated to be 17 with 9 df, what is the approximate probability value?
b. If $x^{2}$ is 17 with 6 df, what is the probability value?
c. What trend ("rule") do you see in the previous two calculations?

Ayushi Balan

Ayushi Balan

Numerade Educator

Problem 2

Inspect Figure $3-8:$ which meiotic stage is responsible for generating Mendel's second law?

Ayushi Balan

Numerade Educator

Problem 3

In Figure $3-9$
a. identify the diploid nuclei.
b. identify which part of the figure illustrates Mendel's first law:

Ayushi Balan

Numerade Educator

Problem 4

Inspect Figure $3-10$ : what would be the outcome in the octad if on rare occasions a nucleus from the postmeiotic mitotic division of nucleus 2 slipped past a nucleus from the postmeiotic mitotic division of nucleus $3 ?$ How could you measure the frequency of such a rare event?

Ayushi Balan

Numerade Educator

Problem 5

In Figure $3-11$, if the input genotypes were $a \cdot B$ and $A \cdot b$ what would be the genotypes colored blue?

Ayushi Balan

Numerade Educator

Problem 6

In the progeny seen in Figure $3-13,$ what are the origins of the chromosomes colored dark blue, light blue, and very light blue?

Ayushi Balan

Numerade Educator

Problem 7

In Figure $3-17$, in which bar of the histogram would the genotype $R_{1} / r_{1} \cdot R_{2} / R_{2} \cdot r_{3} / r_{3}$ be found?

Ayushi Balan

Numerade Educator

Problem 8

In examining Figure $3-19$, what do you think is the main reason for the difference in size of yeast and human mtDNA?

Ayushi Balan

Numerade Educator

Problem 9

In Figure $3-20,$ what color is used to denote cytoplasm containing wild-type mitochondria?

Ayushi Balan

Numerade Educator

Problem 10

In Figure $3-21,$ what would be the leaf types of progeny of the apical (top) flower?

Ayushi Balan

Numerade Educator

Problem 11

From the pedigree in Figure $3-25,$ what principle can you deduce about the inheritance of mitochondrial disease from affected fathers?

Ayushi Balan

Numerade Educator

Problem 12

Assume independent assortment and start with a plant that is dihybrid $A / a ; B / b$
a. What phenotypic ratio is produced from selfing it?
b. What genotypic ratio is produced from selfing it?
c. What phenotypic ratio is produced from testcrossing
it?
d. What genotypic ratio is produced from testcrossing
it?

Ayushi Balan

Numerade Educator

Problem 13

Normal mitosis takes place in a diploid cell of genotype $A / a ; B / b .$ Which of the following genotypes might represent possible daughter cells?
a. $A ; B$
b. $a ; b$
$\mathbf{c} \cdot A ; b$
d. $a ; B$
e. $A / A ; B / B$
f. $A / a ; B / b$
g. $a / a ; b / b$

Ayushi Balan

Numerade Educator

Problem 14

In a diploid organism of $2 n=10,$ assume that you can label all the centromeres derived from its female parent and all the centromeres derived from its male parent. When this organism produces gametes, how many maleand female-labeled centromere combinations are possible in the gametes?

Ayushi Balan

Numerade Educator

Problem 15

It has been shown that when a thin beam of light is aimed at a nucleus, the amount of light absorbed is proportional to the cell's DNA content. Using this method, the DNA in the nuclei of several different types of cells in a corn plant were compared. The following numbers represent the relative amounts of DNA in these different types of cells:
\[
0.7,1.4,2.1,2.8, \text { and } 4.2
\] Which cells could have been used for these measurements? (Note: In plants, the endosperm part of the seed is often triploid, $3 n .$ )

Ayushi Balan

Numerade Educator

Problem 16

Draw a haploid mitosis of the genotype $a^{+} ; b$

Ayushi Balan

Numerade Educator

Problem 17

In moss, the genes $A$ and $B$ are expressed only in the gametophyte. A sporophyte of genotype $A / a ; B / b$ is allowed to produce gametophytes.
a. What proportion of the gametophytes will be $A ; B ?$
b. If fertilization is random, what proportion of sporophytes in the next generation will be $A / a ; B / b ?$

Ayushi Balan

Numerade Educator

Problem 18

When a cell of genotype $A / a ; B / b ; C / c$ having all the genes on separate chromosome pairs divides mitotically, what are the genotypes of the daughter cells?

Ayushi Balan

Numerade Educator

Problem 19

In the haploid yeast Saccharomyces cerevisiae, the two mating types are known as MATa and MATo. You cross a purple $\left(a d^{-}\right)$ strain of mating type $a$ and a white $\left(a d^{+}\right)$ strain of mating type $\alpha$. If $a d^{-}$ and $a d^{+}$ are alleles of one gene, and $a$ and $\alpha$ are alleles of an independently inherited gene on a separate chromosome pair, what progeny do you expect to obtain? In what proportions?

James Kiss

Numerade Educator

Problem 20

In mice, dwarfism is caused by an X-linked recessive allele, and pink coat is caused by an autosomal dominant allele (coats are normally brownish). If a dwarf female from a pure line is crossed with a pink male from a pure line, what will be the phenotypic ratios in the $\mathrm{F}_{1}$ and $\mathrm{F}_{2}$ in each sex? (Invent and define your own gene symbols.)

Dennis Howard

Numerade Educator

Problem 21

Suppose you discover two interesting rare cytological abnormalities in the karyotype of a human male. karyotype is the total visible chromosome complement.) There is an extra piece (satellite) on one of the chromosomes of pair $4,$ and there is an abnormal pattern of staining on one of the chromosomes of pair $7 .$ With the assumption that all the gametes of this male are equally viable, what proportion of his children will have the same karyotype that he has?

Ayushi Balan

Numerade Educator

Problem 22

Suppose that meiosis occurs in the transient diploid stage of the cycle of a haploid organism of chromosome number $n$. What is the probability that an individual haploid cell resulting from the meiotic division will have a complete parental set of centromeres (that is, a set all from one parent or all from the other parent)?

Ayushi Balan

Numerade Educator

Problem 23

Pretend that the year is 1868 . You are a skilled young lens maker working in Vienna. With your superior new lenses, you have just built a microscope that has better resolution than any others available. In your testing of this microscope, you have been observing the cells in the testes of grasshoppers and have been fascinated by the behavior of strange elongated structures that you have seen within the dividing cells. One day, in the library, you read a recent journal paper by
G. Mendel on hypothetical "factors" that he claims explain the results of certain crosses in peas. In a flash of revelation, you are struck by the parallels between your grasshopper studies and Mendel's pea studies, and you resolve to write him a letter. What do you write? (Problem 23 is based on an idea by Ernest Kroeker.)

CY

Coleman Yamakoshi

Numerade Educator

Problem 24

From a presumed testcross $A / a \times a / a,$ in which $A$ represents red and $a$ represents white, use the $x^{2}$ test to find out which of the following possible results would fit the expectations:
a. 120 red, 100 white
b. 5000 red, 5400 white
c. 500 red, 540 white
d. 50 red, 54 white

Hailey Tomashek

Hailey Tomashek

Numerade Educator

Problem 25

Look at the Punnett square in Figure $3-4$
a. How many different genotypes are shown in the 16 squares of the grid?
b. What is the genotypic ratio underlying the 9: 3: 3: 1 phenotypic ratio?
c. Can you devise a simple formula for the calculation of the number of progeny genotypes in dihybrid, trihybrid, and so forth crosses? Repeat for phenotypes.
d. Mendel predicted that, within all but one of the phenotypic classes in the Punnett square, there should be several different genotypes. In particular, he performed many crosses to identify the underlying genotypes of the round, yellow phenotype. Show two different ways that could be used to identify the various genotypes underlying the round, yellow phenotype. (Remember, all the round, yellow peas look identical.)

Jessica Wooten

Numerade Educator

Problem 26

Assuming independent assortment of all genes, develop formulas that show the number of phenotypic classes and the number of genotypic classes from selfing a plant heterozygous for $n$ gene pairs.

Asma Venkitta

Numerade Educator

Problem 27

Note: The first part of this problem was introduced in Chapter $2 .$ The line of logic is extended here.

In the plant Arabidopsis thaliana, a geneticist is interested in the development of trichomes (small projections) on the leaves. A large screen turns up two mutant plants (A and B) that have no trichomes, and these mutants seem to be potentially useful in studying trichome development. (If they are determined by single-gene mutations, then finding the normal and abnormal function of these genes will be instructive.) Each plant was crossed with wild type; in both cases, the next generation $\left(\mathrm{F}_{1}\right)$ had normal trichomes. When $\mathrm{F}_{1}$ plants were selfed, the resulting $\mathrm{F}_{2}$ 's were as follows:
$\mathrm{F}_{2}$ from mutant $\mathrm{A}: 602$ normal $; 198$ no trichomes
$\mathrm{F}_{2}$ from mutant $\mathrm{B}: 267$ normal $; 93$ no trichomes
a. What do these results show? Include proposed genotypes of all plants in your answer.
b. Assume that the genes are located on separate chromosomes. An $\mathrm{F}_{1}$ is produced by crossing the original mutant A with the original mutant
B. This $F_{1}$ is testcrossed: What proportion of testcross progeny will have no trichomes?

John Barone

Numerade Educator

Problem 28

In dogs, dark coat color is dominant over albino, and short hair is dominant over long hair. Assume that these effects are caused by two independently assorting genes. Seven crosses were done as shown below, in which D and A stand for the dark and albino phenotypes, respectively, and $\mathrm{S}$ and
L stand for the short-hair and long-hair phenotypes. Write the genotypes of the parents in each cross. Use the symbols $C$ and $c$ for the dark and albino coat-color alleles and the symbols $H$ and $h$ for the short-hair and long-hair alleles, respectively. Assume parents are homozygous unless there is evidence otherwise.

Jennifer Hudspeth

Jennifer Hudspeth

Numerade Educator

Problem 29

In tomatoes, one gene determines whether the plant has purple (P) or green (G) stems, and a separate, independent gene determines whether the leaves are "cut" (C) or "potato" (Po). Five matings of tomato-plant phenotypes give the following results: a. Which alleles are dominant?
b. What are the most probable genotypes for the parents in each cross?

Sana Riaz

Numerade Educator

Problem 30

A mutant allele in mice causes a bent tail. Six pairs of mice were crossed. Their phenotypes and those of their progeny are given in the following table. $\mathrm{N}$ is normal phenotype; $\mathrm{B}$ is bent phenotype. Deduce the mode of in heritance of bent tail.
a. Is it recessive or dominant?
b. Is it autosomal or sex-linked?
c. What are the genotypes of all parents and progeny?

Rashmi Sinha

Numerade Educator

Problem 31

The normal eye color of Drosophila is red, but strains in which all flies have brown eyes are available. Similarly, wings are normally long, but there are strains with short wings. A female from a pure line with brown eyes and short wings is crossed with a male from a normal pure line. The $F_{1}$ consists of normal females and short-winged males. An $\mathrm{F}_{2}$ is then produced by intercrossing the $\mathrm{F}_{1}$ Both sexes of $\mathrm{F}_{2}$ flies show phenotypes as follows:
$\frac{3}{8}$ red eyes, long wings
$\frac{3}{8}$ red eyes, short wings
$\frac{1}{8}$ brown eyes, long wings
$\frac{1}{8}$ brown eyes, short wings
Deduce the inheritance of these phenotypes; use clearly defined genetic symbols of your own invention. State the genotypes of all three generations and the genotypic proportions of the $\mathrm{F}_{1}$ and $\mathrm{F}_{2}$

Hailey Tomashek

Hailey Tomashek

Numerade Educator

Problem 32

In a natural population of annual plants, a single plant is found that is sickly looking and has yellowish leaves. The plant is dug up and brought back to the laboratory. Photosynthesis rates are found to be very low. Pollen from a normal darks green-leaved plant is used to fertilize emasculated flowers of the yellowish plant. A hundred seeds result, of which only 60 germinate. All the resulting plants are sickly yellow in appearance.
a. Propose a genetic explanation for the inheritance pattern.
b. Suggest a simple test for your model.
c. Account for the reduced photosynthesis, sickliness, and yellowish appearance.

Shiksha Dutta

Numerade Educator

Problem 33

What is the basis for the green-and-white color variegation in the leaves of Mirabilis? If the following cross is made,
\[
\text { variegated } \stackrel{?}{*} \times \text { green } \vec{\delta}
\]
what progeny types can be predicted? What about the reciprocal cross?

Jessica Wooten

Numerade Educator

Problem 34

In Neurospora , the mutant stp exhibits erratic stop-andstart growth. The mutant site is known to be in the $\mathrm{mtD}$ NA. If an stp strain is used as the female parent in a cross with a normal strain acting as the male, what type of progeny can be expected? What about the progeny from the reciprocal cross?

Asma Venkitta

Numerade Educator

Problem 35

Two corn plants are studied. One is resistant (R) and the other is susceptible (S) to a certain pathogenic fungus. The following crosses are made, with the results shown:
\[
\begin{array}{l}
\mathrm{S} \stackrel{\mathrm{q}} \times \mathrm{R} \delta \rightarrow \text { all progeny } \mathrm{S} \\
\mathrm{R} \stackrel{9} \times \mathrm{S} \delta \rightarrow \text { all progeny } \mathrm{R}
\end{array}
\]
What can you conclude about the location of the genetic determinants of $\mathrm{R}$ and $\mathrm{S}$ ?

John Barone

Numerade Educator

Problem 36

A presumed dihybrid in Drasophila, $B / b ; F / f,$ is testcrossed with $b / b ; f / f$. $(B=\text { black body } ; b=$ brown body $F=\text { forked bristles } f=\text { unforked bristles. })$ The results are
black, forked $230 \quad$ brown, forked $\quad 240$ black, unforked $210 \quad$ brown, unforked 250
Use the $x^{2}$ test to determine if these results fit the results expected from testcrossing the hypothesized dihybrid.

Dennis Howard

Numerade Educator

Problem 37

Are the following progeny numbers consistent with the results expected from selfing a plant presumed to be a dihybrid of two independently assorting genes, $H / h$;
\[
R / r ?(H=\text { hairy leaves; } h=\operatorname{smooth} \text { leaves; } R=\text { round }
\]
ovary; $r=$ elongated ovary.) Explain your answer.
hairy, round $178 \quad$ smooth, round hairy, elongated $62 \quad$ smooth, elongated 24

Joanna Quigley

Numerade Educator

Problem 38

A dark female moth is crossed with a dark male. All the male progeny are dark, but half the female progeny are light and the rest are dark. Propose an explanation for this pattern of inheritance.

John Barone

Numerade Educator

Problem 39

In Neurospora, a mutant strain called stopper (stp) arose spontaneously. Stopper showed erratic "stop and start" growth, compared with the uninterrupted growth of wild-type strains. In crosses, the following results were found:
? stopper $\times \phi$ wild type $\rightarrow$ progeny all stopper ? wild type $\times \delta$ stopper $\rightarrow$ progeny all wild type
a. What do these results suggest regarding the location of the stopper mutation in the genome?
b. According to your model for part $a$, what progeny and proportions are predicted in octads from the following cross, including a mutation nic3 located on chromosome VI?
9 stp $\cdot$ nic $3 \times$ wild type $\delta$

Mikayla Stephens

Mikayla Stephens

Numerade Educator

Problem 40

In polygenic systems, how many phenotypic classes corresponding to number of polygene "doses" are expected in selfs
a. of strains with four heterozygous polygenes?
b. of strains with six heterozygous polygenes?

Bryan Lynn

Numerade Educator

Problem 41

In the self of a polygenic trihybrid $R_{1} / r_{1} ; R_{2} / r_{2} ; R_{3} / r_{3}$ use the product and sum rules to calculate the proportion of progeny with just one polygene "dose."

Abigail Schammel

Abigail Schammel

Numerade Educator

Problem 42

Reciprocal crosses and self were performed between the two moss species Funaria mediterranea and F.hygro metrica. The sporophytes and the leaves of the gametophytes are shown in the accompanying diagram.

Joanna Quigley

Numerade Educator

Problem 43

Assume that diploid plant A has a cytoplasm genetically different from that of plant B. To study nuclear-cytoplasmic relations, you wish to obtain a plant with the cytoplasm of plant A and the nuclear genome predominantly of plant
B. How would you go about producing such a plant?

Hailey Ames

Numerade Educator

Problem 44

You are studying a plant with tissue comprising both green and white sectors. You wish to decide whether this phenomenon is due (1) to a chloroplast mutation of the type considered in this chapter or (2) to a dominant nuclear mutation that inhibits chlorophyll production and is present only in certain tissue layers of the plant as a mosaic. Outline the experimental approach that you would use to resolve this problem.

Jessica Wooten

Numerade Educator

Problem 45

You have three jars containing marbles, as follows:
jar $1 \quad 600$ red and 400 white
jar $2 \quad 900$ blue and 100 white jar $3 \quad 10$ green and 990 white
a. If you blindly select one marble from each jar, calculate the probability of obtaining
(1) a red, a blue, and a green.
(2) three whites.
(3) a red, a green, and a white.
(4) a red and two whites.
(5) a color and two whites.
(6) at least one white.
b. In a certain plant, $R=\operatorname{red}$ and $r=$ white. You self a red
$R / r$ heterozygote with the express purpose of obtaining a white plant for an experiment. What minimum number of seeds do you have to grow to be at least 95 percent certain of obtaining at least one white individual?
c. When a woman is injected with an egg fertilized in vitro, the probability of its implanting successfully is
20 percent. If a woman is injected with five eggs simultaneously, what is the probability that she will become pregnant? (Part $c$ is from Margaret Holm.)

Rashmi Sinha

Numerade Educator

Problem 46

In tomatoes, red fruit is dominant over yellow, two-loculed fruit is dominant over many-loculed fruit, and tall vine is dominant over dwarf. A breeder has two pure lines:
(1) red, two-loculed, dwarf and (2) yellow, manyloculed, tall. From these two lines, he wants to produce a new pure line for trade that is yellow, two-loculed, and tall. How exactly should he go about doing so? Show not only which crosses to make, but also how many progeny should be sampled in each case.

Bryan Valdivia

Numerade Educator

Problem 47

We have dealt mainly with only two genes, but the same principles hold for more than two genes. Consider the following cross:
\[
A / a ; B / b ; C / c ; D / d ; E / e \times a / a ; B / b ; c / c ; D / d ; e / e
\]
a. What proportion of progeny will phenotypically resemble (1) the first parent,
(2) the second parent,
(3) either parent, and (4) neither parent?
b. What proportion of progeny will be genotypically the same as (1) the first parent,
(2) the second parent,
(3) either parent, and (4) neither parent?
Assume independent assortment.

Emili Wallace

Numerade Educator

Problem 48

The accompanying pedigree shows the pattern of transmission of two rare human phenotypes: cataract and pituitary dwarfism. Family members with cataract are shown with a solid left half of the symbol; those with pituitary dwarfism are indicated by a solid right half. a. What is the most likely mode of inheritance of each of these phenotypes? Explain.
b. List the genotypes of all members in generation III as far as possible.
c. If a hypothetical mating took place between IV-1 and IV-5, what is the probability of the first child's being a dwarf with cataracts? A phenotypically normal child? (Problem 48 is adapted from $J$. Kuspira and $R$. Bhambhani, Compendium of Problems in Genetics. Copyright 1994 by Wm. C. Brown.)

Jessica Wooten

Numerade Educator

Problem 49

A corn geneticist has three pure lines of genotypes $a / a ; B / B ; C / C, A / A ; b / b ; C / C,$ and $A / A ; B / B ; c / c .$ All
the phenotypes determined by $a, b,$ and $c$ will increase the market value of the corn; so, naturally, he wants to combine them all in one pure line of genotype $a / a ; b / b ; c / c$
a. Outline an effective crossing program that can be used to obtain the $a / a ; b / b ; c / c$ pure line.
b. At each stage, state exactly which phenotypes will be selected and give their expected frequencies.
c. Is there more than one way to obtain the desired genotype? Which is the best way?

Shiksha Dutta

Numerade Educator

Problem 50

In humans, color vision depends on genes encoding three pigments. The $R$ (red pigment) and $G$ (green pigment ) genes are close together on the $X$ chromosome, whereas the $B$ (blue pigment) gene is autosomal. A recessive mutation in any one of these genes can cause color blindness. Suppose that a color-blind man married a woman with normal color vision. The four sons from this marriage were color-blind, and the five daughters were normal. Specify the most likely genotypes of both parents and their children, explaining your reasoning. (A pedigree drawing will probably be helpful.) (Problem 50 is by Rosemary Redfield.)

Jessica Wooten

Numerade Educator

Problem 51

Consider the accompanying pedigree for a rare human muscle disease. a. What unusual feature distinguishes this pedigree from those studied earlier in this chapter?
b. Where do you think the mutant DNA responsible for this phenotype resides in the cell?

Dennis Howard

Numerade Educator

Problem 52

The plant Haplopappus gracilis has a $2 n$ of $4 .$ A diploid cell culture was established and, at premitotic $\mathrm{S}$ phase, a radioactive nucleotide was added and was incorporated into newly synthesized DNA. The cells were then removed from the radioactivity, washed, and allowed to proceed through mitosis. Radioactive chromosomes or chromatids can be detected by placing photographic emulsion on the cells; radioactive chromosomes or chromatids appeared covered with spots of silver from the emulsion. (The chromosomes "take their own photograph.") Draw the chromosomes at prophase and telophase of the first and second mitotic divisions after the radioactive treatment. If they are radioactive, show it in your diagram. If there are several possibilities, show them, too.

James Kiss

Numerade Educator

Problem 53

In the species of Problem $52,$ you can introduce radioactivity by injection into the anthers at the S phase before meiosis. Draw the four products of meiosis with their chromosomes, and show which are radioactive.

Noah Boudrie

Numerade Educator

Problem 54

The plant Haplopappus gracilis is diploid and $2 n=4$ There are one long pair and one short pair of chromosomes. The diagrams below (numbered 1 through 12) represent anaphases ("pulling apart" stages) of individual cells in meiosis or mitosis in a plant that is genetically
a dihybrid $(A / a ; B / b)$ for genes on different chromosomes. The lines represent chromosomes or chromatids, and the points of the $\mathrm{V}$ 's represent centromeres. In each case, indicate if the diagram represents a cell in meiosis
I, meiosis II, or mitosis. If a diagram shows an impossible situation, say so.

Shiksha Dutta

Numerade Educator

Problem 55

The pedigree below shows the recurrence of a rare neurological disease (large black symbols) and spontaneous fetal abortion (small black symbols) in one family. (A slash means that the individual is deceased.) Provide an explanation for this pedigree in regard to the cytoplasmic segregation of defective mitochondria.

Shiksha Dutta

Numerade Educator

Problem 56

A man is brachydactylous (very short fingers; rare autosomal dominant), and his wife is not. Both can taste the chemical phenylthiocarbamide (autosomal dominant; common allele), but their mothers could not
a. Give the genotypes of the couple.
If the genes assort independently and the couple has four children, what is the probability of
b. all of them being brachydactylous?
c. none being brachydactylous?
d. all of them being tasters?
e. all of them being nontasters?
f. all of them being brachydactylous tasters?
g. none being brachydactylous tasters?
h. at least one being a brachydactylous taster?

Anand Jangid

Numerade Educator

Problem 57

One form of male sterility in corn is maternally transmitted. Plants of a male-sterile line crossed with normal pollen give male-sterile plants. In addition, some lines of corn are known to carry a dominant nuclear restorer allele $(R f)$ that restores pollen fertility in male-sterile lines.
a. Research shows that the introduction of restorer alleles into male-sterile lines does not alter or affect the maintenance of the cytoplasmic factors for male sterility. What kind of research results would lead to such a conclusion?
b. $A$ male-sterile plant is crossed with pollen from a plant homozygous for $R f$. What is the genotype of the $\mathrm{F}_{1} ?$ The phenotype?
c. The $F_{1}$ plants from part $b$ are used as females in a testcross with pollen from a normal plant $(r f / r f)$. What are the results of this testcross? Give genotypes and phenotypes, and designate the kind of cytoplasm.
d. The restorer allele already described can be called
$R f$ -1. Another dominant restorer, $R f$ - 2 , has been found. $R f \cdot 1$ and $R f \cdot 2$ are located on different chromosomes. Either or both of the restorer alleles will give pollen fertility. With the use of a male-sterile plant as a tester, what will be the result of a cross in which the male
parent is
(1) heterozygous at both restorer loci?
(2) homozygous dominant at one restorer locus and homozygous recessive at the other?
(3) heterozygous at one restorer locus and homozygous recessive at the other?
(4) heterozygous at one restorer locus and homozygous dominant at the other?

Hailey Tomashek

Hailey Tomashek

Numerade Educator