Two different genes control the expression of kernel colour in Mexican black corn: a black pigment gene (B) and a dotted pigment gene (D). Gene B influences the expression of gene D. The dotted phenotype appears only when gene B is in the homozygous recessive state. A colourless variation occurs when both genes are homozygous recessive. After pure-breeding black-pigmented plants were crossed with colourless plants, all offspring were black-pigmented. 1. The genotypes of the parents of these F1 offspring could be a. BBDD × bbdd b. BbDD × bbdd c. Bbdd × bbDD d. bbDD × BBdd 2. Plants of the F1 generation are suspected of being heterozygous for both genes. A test cross of colourless plants with the heterozygote plants should produce a genotypic ratio in the offspring of a. 1:0 b. 3:1 c. 2:1:1 d. 1:1:1:1

Two different genes control the expression of kernel colour in Mexican black corn: a black pigment gene (B) and a dotted pigment gene (D). Gene B influences the expression of gene D. The dotted phenotype appears only when gene B is in the homozygous recessive state. A colourless variation occurs when both genes are homozygous recessive. After pure-breeding black-pigmented plants were crossed with colourless plants, all offspring were black-pigmented. 1. The genotypes of the parents of these F1 offspring could be a. BBDD × bbdd b. BbDD × bbdd c. Bbdd × bbDD d. bbDD × BBdd 2. Plants of the F1 generation are suspected of being heterozygous for both genes. A test cross of colourless plants with the heterozygote plants should produce a genotypic ratio in the offspring of a. 1:0 b. 3:1 c. 2:1:1 d. 1:1:1:1

Name: Two different genes control the expression of kernelcolour in Mexican
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Description: Two different genes control the expression of kernelcolour in Mexican black corn: a black pigment gene (B)and a dotted pigment gene (D). Gene B influences theexpression of gene D. The dotted phenotype appearsonly when gene B is in the homozygous rece

Human Biology (MindTap Course List)

11th Edition

ISBN:9781305112100

Author:Cecie Starr, Beverly McMillan

Publisher:Cecie Starr, Beverly McMillan

Chapter20: Chromosomes And Human Genetics

Section: Chapter Questions

Problem 7CT: The following pedigree shows the pattern of inheritance of red-green color blindness in a family....

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Two different genes control the expression of kernelcolour in Mexican black corn: a black pigment gene (B)and a dotted pigment gene (D). Gene B influences theexpression of gene D. The dotted phenotype appearsonly when gene B is in the homozygous recessivestate. A colourless variation occurs when both genesare homozygous recessive.After pure-breeding black-pigmented plants werecrossed with colourless plants, all offspring wereblack-pigmented. The genotypes of the parents of these F1 offspring could bea. BBDD × bbddb. BbDD × bbddc. Bbdd × bbDDd. bbDD × BBdd
In Drosophila, the autosomal recessive dp allele ofthe dumpy gene produces short, curved wings, whilethe autosomal recessive allele bw of the brown genecauses brown eyes. In a testcross using femalesheterozygous for both of these genes, the followingresults were obtained:wild-type wings, wild-type eyes 178wild-type wings, brown eyes 185dumpy wings, wild-type eyes 172dumpy wings, brown eyes 181In a testcross using males heterozygous for both ofthese genes, a different set of results was obtained:wild-type wings, wild-type eyes 247dumpy wings, brown eyes 242a. What can you conclude from the first testcross?b. What can you conclude from the second testcross?c. How can you reconcile the data shown in parts (a)and (b)? Can you exploit the difference betweenthese two sets of data to devise a general test forsynteny in Drosophila?d. The genetic distance between dumpy and brown is91.5 m.u. How could this value be measured?
. The production of pigment in the outer layer of seedsof corn requires each of the three independently assorting genes A, C, and R to be represented by at leastone dominant allele, as specified in Problem 64. Thedominant allele Pr of a fourth independently assortinggene is required to convert the biochemical precursorinto a purple pigment, and its recessive allele pr makesthe pigment red. Plants that do not produce pigmenthave yellow seeds. Consider a cross of a strain of genotype A/A ; C/C ; R/R ; pr/pr with a strain of genotypea/a ; c/c ; r/r ; Pr/Pr.a. What are the phenotypes of the parents?b. What will be the phenotype of the F1?c. What phenotypes, and in what proportions, willappear in the progeny of a selfed F1?d. What progeny proportions do you predict from thetestcross of an F1?
In humans, the genetic disease cystic fibrosis is caused by a recessive allele (a). The normal (healthy) allele is dominant (A). What is the genotype of someone who has cystic fibrosis? What are the two different genotypes that a healthy person could have? If two people were both heterozygous for the cystic fibrosis gene, what fraction of their children would be likely to have this disease? Hint: Draw a Punnett square to figure it out.
Another recessive mutation in Drosophila, ebony (e), is on anautosome (chromosome 3) and causes darkening of the bodycompared with wild-type flies. What phenotypic F1 and F2 maleand female ratios will result if a scalloped-winged female withnormal body color is crossed with a normal-winged ebony male?Work this problem by both the Punnett square method and theforked-line method.
. A true-breeding strain of Virginia tobacco has dominantalleles determining leaf morphology (M), leaf color(C), and leaf size (S). A Carolina strain is homozygousfor the recessive alleles of these three genes. Thesegenes are found on the same chromosome as follows:M C S6 m.u. 17 m.u.An F1 hybrid between the two strains is now backcrossedto the Carolina strain. Assuming no interference:a. What proportion of the backcross progeny willresemble the Virginia strain for all three traits?b. What proportion of the backcross progeny willresemble the Carolina strain for all three traits?c. What proportion of the backcross progeny will havethe leaf morphology and leaf size of the Virginiastrain but the leaf color of the Carolina strain?d. What proportion of the backcross progeny will havethe leaf morphology and leaf color of the Virginiastrain but the leaf size of the Carolina strain?
In mice, the AYallele of the agouti gene is a recessivelethal allele, but it is dominant for yellow coat color.What phenotypes and ratios of offspring would youexpect from the cross of a mouse heterozygous at theagouti gene (genotype AYA) and also at the albinogene (Cc) to an albino mouse (cc) heterozygous at theagouti gene (AYA)?
In the fruit fly, recessive mutations in either of two independently assorting genes, brown and purple, prevent the synthesis of red pigment in the eyes. Thus, homozygotes for either of these mutations have brownish-purple eyes. However, heterozygotes for both of these mutations have dark red, that is, wild-type eyes. If such double heterozygotes are intercrossed, what kinds of progeny will be produced, and in what proportions?
Two different genes control the expression of kernel colour in Mexican black corn: a black pigment gene (B) and a dotted pigment gene (D). Gene B influences the expression of gene D. The dotted phenotype appears only when gene B is in the homozygous recessive state. A colourless variation occurs when both genes are homozygous recessive. After pure-breeding black-pigmented plants were crossed with colourless plants, all offspring were black-pigmented. Plants of the F 1generation are suspected of being heterozygous for both genes. A test cross of colourless plants with the heterozygote plants should produce a genotypic ratio in the offspring of A. 1:0 B. 3:1 C. 2:1:1 D. 1:1:1:1
When many families were tested for the ability to tastethe chemical phenylthiocarbamide, the matings weregrouped into three types and the progeny were totaled,with the results shown below:ChildrenNumber NonParents of families Tasters tastersTaster × taster 425 929 130Taster × nontaster 289 483 278Nontaster × nontaster 86 5 218With the assumption that PTC tasting is dominant (P)and nontasting is recessive (p), how can the progenyratios in each of the three types of mating be accountedfor?
Three recessive traits in garden pea plants are as follows: yellowpods are recessive to green pods, bluish green seedlings are recessiveto green seedlings, creeper (a plant that cannot stand up) isrecessive to normal. A true-breeding normal plant with green podsand green seedlings was crossed to a creeper with yellow pods andbluish green seedlings. The F1 plants were then crossed to creeperswith yellow pods and bluish green seedlings. The following resultswere obtained: 2059 green pods, green seedlings, normal151 green pods, green seedlings, creeper281 green pods, bluish green seedlings, normal15 green pods, bluish green seedlings, creeper2041 yellow pods, bluish green seedlings, creeper157 yellow pods, bluish green seedlings, normal282 yellow pods, green seedlings, creeper11 yellow pods, green seedlings, normal Construct a genetic map that indicates the map distances betweenthese three genes?
In mice, the wild-type coat color, agouti (AA) [left mouse], is dominant to solid-colored, black fur (aa) [middle mouse]. However, a separate gene (C) is necessary for pigment production. A mouse that is homozygous for a recessive c allele at this locus is unable to produce pigment and is albino [right mouse] regardless of the allele present at locus A. Thus, the following genotypes are listed with their associated phenotypes: ~ A/A; C/C or A/A; C/c or A/a; C/C or A/a; C/c ==> "agouti" ~ a/a; C/C or a/a; C/c ==> "black" ~ A/A; c/c or A/a; c/c or a/a; c/c or a/a; c/c ==> "albino" This is an example of recessive epistasis, in which the recessive c allele "stands upon" the possible genotypes for the A gene (A/A, A/a, or a/a). If two agouti mice with the A/a; C/c genotype are mated, what is the expected phenotypic ratio in their offspring? A.9 albino, 4 agouti, 3 black B. 9 agouti, 4 albino, 3 black C.9 black, 4 albino, 3 agouti D.9 agouti, 4 black, 3 albino