Concept explainers
Blue flower color is produced in a species of morning glories when dominant alleles are present at two gene loci, A and B. (Plants with the genotype A–B– have blue flowers.) Purple flowers result when a dominant allele is present at only one of the two gene loci, A or B. (Plants with the genotypes A–bb and aaB– are purple.) Flowers are red when the plant is homozygous recessive for each gene (i.e., aabb). a. Two pure-breeding purple strains are crossed, and all the
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Chapter 4 Solutions
GENETIC ANALYSIS: AN INTEG. APP. W/MAS
- A researcher at ASU is studying the exotic Unicorn Fairy plant. The plant has three genes of interest with the dominant alleles being T-tall, H=hairy leaves and P=purple flowers. The three genes are located in different chromosomes. A trihybrid plant is crossed with a plant that is heterozygous for T and homozygous recessive for the other two genes. What is the probability of getting offspring that is tall, has hairy leaves and white flowers? 9/64 5/8 8/64 O 3/64 O 3/16arrow_forwardCan you please help find how many black leaves there are?arrow_forwardStem length in plants is controlled by two CODOMINANT alleles of one autosomal - one allele, B, adds 2 cm to the length of the plant, and another allele, b reduces length by 0.5 cm. The base length of the plant's stem is 10 cm. A plant breeder wants to breed plants that are exactly 14.5 cm in stem length. He starts with crossing two heterozygotes, Bb x Bb. gene Assuming that you can ONLY breed plants of the same stem length, what cross(es) would the breeder have to set up in order to achieve this? Let's (i) (ii) that stem length segregates independently from flower color (also a say monogenic, autosomal, biallelic trait). If you crossed a homozygote from (i) i.e. a bb and homozygote red flowers with a plant that is homozygote BB and homozygote white flowers, intercross the F1, and observe the following numbers of progeny in the F2 generation: (iii) Height Flower Color Observed Number 14 cm Red 2 14 cm 14 cm Pink White 11.5 cm Red 7 11.5 cm Pink 13 11.5 cm White 6. 9 cm Red 9 cm Pink 6.…arrow_forward
- If an allotetraploid species is made up of two ancestral genomes, A and B, with each of them having a basic chromosome number of seven. The resistance to the pathogen attacking the foliage of plants is controlled by a dominant allele located at the F locus. The recessive alleles F^a and F^b show sensitivity to the pathogen. Plants with at least on F^A allele are resistant to the pathotype 1 and 2 (regardless of the genotype in B genome), and plants with at least one F^B allele are resistant to pathotypes 1 and 3 (regardless of genotype in A genome). What proprtion of the self-progeny of F^AF^a F^BF^b plant will be resistant to pathotype 1, 2 and 3?arrow_forwardColored aleurone in the kernels of corn is due to the dominant allele R. The recessive allele r, when homozygous, produces colorless aleurone. The plant color (not kernel color) is controlled by another gene with two alleles, Y and y. The dominant Y allele results in green color, whereas the homozygous presence of the recessive y allele causes the plant to appear yellow. In a testcross between a plant of unknown genotype and phenotype and a plant that is homozygous recessive for both traits, the following progeny were obtained: colored, green 88colored, yellow 12colorless, green 8colorless, yellow 92Explain how these results were obtained by determining theexact genotype and phenotype of the unknown plant, including the precise association of the two genes on the homologs (i.e., the arrangement).arrow_forwardIn com, colored aleurone (in the kernels) is due to the dominant allele R. The recessive allele r, when homozygous, produces colorless aleurone. The plant color (not the kernel color) is controlled by another gene with two alleles Y and y. The dominant Y allele results in green color, whereas the homozygous presence of the recessive y allele causes the plant to appear yellow. In a testcross between a plant of unknown genotype and phenotype and a plant that is homozygous recessive for both traits, the following progeny were obtained. Numbers of Offspring Phenotype Colored Aleurone & Green Plant 88 Colored Aleurone & Yellow Plant 12 Colorless Aleurone & Green Plant 8 Colorless Aleurone & Yellow Plant 92 Question: Determine the genotype and phenotype of the unknown plant, including the precise association of the two genes on the homologs (i.e. the map arrangement)arrow_forward
- Flower color in petunias is determined by the biochemical pathway shown below: A_ B_ C_ Yellow Orange > Green Blue aa bb Plants of genotype AAbbcc were mated to plants of genotype AaBbCc. Determine the phenotypic ratio expected from this cross and fill in the spaces in the ratio below with whole numbers in lowest form. lf none are expected in a class, then type the number 0 in the space. Yellow: Orange : Green: Bluearrow_forwardIn genetics, the dash symbol (–) is a “wild card” that stands for either the dominant allele or the recessive allele; for example, A– means the individual has either the genotype AA or Aa. Two genes that undergo independent assortment affect coat color in Duroc pigs. Each gene has two alleles, one of which is dominant for coat color. Genotypes of the form A– B– are red, those of the form A– bb and aa B– are sandy, and genotype aa bb is white. What ratio of red:sandy:white is expected from the cross Aa Bb x Aa Bb?arrow_forwardLet us suppose that two plants are crossed (mated). One plant (female) is homozygous dominant and produces chlorophyll, and the other (male) is homozygous recessive and does not produce chlorophyll. These two plants are considered the parental, or P generation. What would be the possible genotypes and phenotypes of these two individuals? Fill in the table below with the parental generation's descriptional information. Table 6.1 Female Male Description Parental Generation Homozygous dominant P Generation Genotype gg Phenotype Greenarrow_forward
- In a certain plant, the dominant form of gene B codes for blue fruit, while the recessive form results in pink fruit. The dominant form of another gene, E, inhibits the activity of the enzyme coded for by gene B, resulting in white fruit, while the recessive form is unable to inhibit this enzyme and results in colored (i.e., blue or pink) fruit. A doubly-homozygous dominant white-fruited plant is crossed with a pink-fruited plant. The F1 progeny were then self-crossed to generate the F2 generation. Determine the ratios of genotypes and phenotypes for each generation.arrow_forwardTwo 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. 1:1:1:1arrow_forwardGene A controls the sharpness of spines in a type of cactus. Cactuses with the dominant allele, A, have sharp spines, whereas homozygous recessive aa cactuses have dull spines. At the same time, a second gene, N, determines whether cactuses have spines at all. Homozygous recessive nn cactuses have no spines at all. a) The relationship between genes A and N is an example of ________________ b) A cactus with sharp spines is crossed with a spineless cactus. All the offspring have spines but approximately half of the 100 offspring have dull spines and half have sharp spines. What are the genotypes of the parent cacti?arrow_forward
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