To review:
There are many varieties of rice that are tolerant or intolerant to floods. The true breeding-intolerant varieties are
1. Results of the cross |
Number of plants | ||
Tolerant (Alive) | Intolerant (Dead) | Total | |
On the basis of the data given for the various crosses, justify that it supports that tolerance is a dominant trait with the help of genotypes and phenotypes.
Introduction:
A cross used to determine the phenotypes of parents is known as a test cross. The parent plant is crossed with the plant with the recessive genotype. If the ratio of dominant to recessive in the progeny is 3:1, the parent is true-breeding dominant, whereas if the ratio is
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Chapter 12 Solutions
Biology: The Dynamic Science (MindTap Course List)
- Half of the worlds population eats rice at least twice a day. Much of this rice is grown in flooded conditions, and different strains of rice are tolerant (survive) or intolerant (die) under these conditions. Rice breeders used genetic crosses to test whether tolerance to flooding is a dominant trait. Researchers used three true-breeding flood-tolerant strains, FR143, BKNFR, and Kurk, and two true-breeding flood- intolerant strains, IR42 and NB, in the crosses. Results were obtained from three sets of crosses and are reported in the Table below: Results of cross of F1 to tolerant parent: F1 plants were crossed with the tolerant parent of the cross. Number of Plants Progeny Analyzed from Intolerant Tolerant Cross Alive Dead Total 1. F2 results of cross: IR42 FR13A 187 77 264 IR42 BKNFR 192 73 265 NB Kurk 142 52 195 2. Results of cross of F1 to intolerant parent: (F1 of IR42 FR13A) IR42 14 17 31 (F1 of IR42 BKNFR) IR42 15 10 25 (F1 of NB Kurk) NB 21 35 56 3. Results of cross of F1 to tolerant parent: (F1 of IR42 FR13A) FR13A 31 0 31 (F1 of IR42 BKNFR) BKNFR 28 0 28 (F1 of NB Kurk) Kurk 40 0 40 Do the data support the hypothesis that the tolerance trait is dominant? Justify your conclusion by explaining the results from each of the three sets of crosses in terms of genotypes and phenotypic ratios. Source: T. Setter et al. 1997. Physiology and genetics of submergence tolerance in rice. Annals of Botany 79:6777.arrow_forwardThe gene for pea pod colour has two alleles. The dominant allele, G, is associated with the dominant trait of green pea pod colour. The recessive allele, g, is associated with the recessive trait of yellow pea pod colour. For many years, there has been a large collection of pea plants with a mixture of yellow and green pea pod colours in a savannah. But there has been a recent infestation of wild rabbits with a preference for eating plants with yellow pea pods. Assume that at the start of the infestation, the alleles in the pea plant population were in Hardy-Weinberg equilibrium. (a) What does it mean for the alleles in the pea plant population to be in Hardy-Weinberg equilibrium? (b) What is expected to happen to the allele frequency of the g allele in the subsequent pea generations after the rabbits have been introduced? Explain your answer using terms from Darwinian evolution.arrow_forward2) The year is 2050. The climate has continued to warm. Areas in northern Canada and Alaska are without snow or ice; the average annual temperature has risen and previously snow-covered areas are now shrub land and some temperate forests. What effect would such a climatic change have on the gene pool of the rabbits? All BUT ONE could apply. A) The allelic frequency has most likely shifted to 85% GG and 15% gg. B) The dominant allele in the gene pool would become G, the previously rare allele. C) The allele for white, g, would be scarce and perhaps nonexistent in the population. D) White rabbits would be at a disadvantage in terms of camouflage and would likely fall prey to predators.arrow_forward
- A mountain region has a population of 5,000 mountain goats. You score these animals for the R locus and find that this locus has two alleles, R (dominant) and r (recessive). 3200 individuals are homozygous dominant, 1,600 are heterozygous, and 200 are homozygous recessive. A deadly virus infects all of the RR mountain goats in the population (above), killing all individuals of this genotype and leaving the population with only the rr and Rr mountain goats. a) Calculate the new allele frequencies for this population. Show your work. b) Calculate the new (observed) genotypic frequencies for this population. Show your work. c) Does this population still appear to be at H-W equilibrium? Why or why not? (You do not need to analyze this statistically).arrow_forwardA large, genetically heterogeneous group of tomato plants was usedas the original breeding stock by two different breeders, namedMary and Hector. Each breeder was given 50 seeds and began aselective breeding strategy, much like that described in Figure24.11. The seeds were planted, and the breeders selected the 10plants with the highest mean tomato weights as the breeding stockfor the next generation. This process was repeated over the courseof 12 growing seasons, and the following data were obtained: A. Explain these results.B. Another tomato breeder, named Martin, got some seeds fromMary’s and Hector’s tomato strains (after 12 generations),grew the plants, and then crossed them to each other. The mean weight of the tomatoes in these hybrids was about 1.7 pounds.For a period of 5 years, Martin subjected these hybrids to thesame selective breeding strategy that Mary and Hector had followed,and he obtained the following results: Explain Martin’s data. Why was Martin able to obtain…arrow_forwardWhat is the chi-square value of the pumpkin population? round up and use four decimal points After doing some crosses and genotyping some individuals, you determined that the number of individuals homozygous dominant for the largest pumpkin allele is 98, 80 are heterozygous for medium size, and 20 are homozygous recessive for small size.arrow_forward
- > NEXT A BOOKMARK Question 23/28 According to the probability of the pea plant offspring in chart 2, what percentage of the offspring will be yellow in color? Use the diagrams below to answer the questions that follow. 23 Pea Plants Chart 1 A 5% Punnett Square B) 19% с) 30% Aa Aa D 25% Aa A a E) 75% Chart 2 AaBb x AaBb AB Ab aB ab Key AB AABB AABB Ab AABB AABB AaBb AA - Green BB - Smooth AAbb AaBb Aabb AABB AaBb aa - Yellow aB AaBb aaBB aaBb bb - Rough ab Aabb aaBb aabbarrow_forwardYou are studying an isolated population of irises on an island off the coast of Maine. Plants in this population exhibit three different phenotypes for stem hair. ShSh plants are hairy, SsSs plants are smooth, and ShSs plants have intermediate amounts of stem hair. After characterizing stem phenotypes for a sample of the population, you classify 450 plants as having hairy stems, 701 as having intermediate hairy stems, and 112 as having smooth stems. Is the population in Hardy-Weinberg Equilibrium with respect to stem hair? ___YES______NO # Justify your answer. Edit View Insert Format Tools Table Paragraph✓ BI U 12pt v 80 F3 $ 000 000 F4 % F5 <arrow_forwardIn humans, Rh+ individuals have the Rh antigen on their red blood cells, while Rh− individuals do not. Assume that a dominant gene Rh produces the Rh+ phenotype, and that the recessive rh allele produces the Rh− phenotype. In a population that is in Hardy-Weinberg equilibrium, if 160 out of 200 individuals are Rh+, calculate the frequencies of both alleles.arrow_forwardA scientist is studying a wild population of Japanese morning glories. It is easy to separate genotypes at a flower color locus by their phenotypes. Red individuals are homozygous for the R allele, yellow individuals are homozygous for the Y allele, and orange individuals are heterozygous. If the number of individuals with the following genotypes are: RR: 831 RY: 33 YY: 442 Is the population in Hardy Weinberg Equilibrium?arrow_forwardCockroaches from the dormitories at Texas A&M University usually weigh about 1 gram. However, about 100 miles west of the university is a colony of much larger cockroaches in which some individuals obtain a weight of as much as 25 grams. These cockroaches of unusual size (COUS) have apparently evolved to consume the large supply of garbage that exists in the region. If a 25-gram cockroach is crossed with a 1-gram cockroach, their progeny grow uniformly to a size of about 13 grams. If two of these 13-gram (F1) cockroaches are crossed, cockroach sizes from 1 gram to 25 grams are produced. However, the 1-gram and the 25-gram cockroaches are rare, occurring at a frequency in each case of about 1 in 64. If a 13-gram F1 cockroach is crossed with a 1-gram cockroach, how frequently are 9-gram cockroaches expected? Cockroaches from the dormitories at Texas A&M University usually weigh about 1 gram. However, about 100 miles west of the university is a colony of much larger…arrow_forwardTABLE 1 Data for Bean Simulation for F1 and F2 Generations: F1 Generation GENOTYPES TOTALS Observed Frequency of Observed frequency of Genotypes = proportion alleles out of 50 BLACK, BLACK (AA) A= 12 BLACK, WHITE (Aa) 19 a= WHITE, WHITE (aa) 19 F2 Generation BLACK, BLACK (AA) A= 14 BLACK, WHITE (Aa) 24 a= WHITE, WHITE (aa) 12arrow_forwardarrow_back_iosSEE MORE QUESTIONSarrow_forward_ios
- Biology: The Dynamic Science (MindTap Course List)BiologyISBN:9781305389892Author:Peter J. Russell, Paul E. Hertz, Beverly McMillanPublisher:Cengage Learning