In: Biology
1. There are four loci in wild sorghum that each contribute equally to the height of the plant. The smallest plant is 2 feet tall. When homozygous for contributing alleles at all four loci, however, the plant stands at 10 feet tall. If one crosses a small sorghum plant (2 ft tall) with a giant sorghum plant, the F1 are all 6 feet tall. Letting the F1 self-pollinate, how often will a plant 8 feet tall be found in the F2 progeny?
A. 1/64 | ||||||||||||||
B. 6/64 | ||||||||||||||
C. 7/64 | ||||||||||||||
D. 20/64 2. There are four loci in wild sorghum that each contribute equally to the height of the plant. The smallest plant is 2 feet tall. When homozygous for contributing alleles at all four loci, however, the plant stands at 10 feet tall. Based on the above information, what is the individual allelic contribution to the overall height of the plant?
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Answer 1 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Given information: Smallest plant (base height) = 2 feet Tallest plant = 10 feet Let the alleles be A,a, B,b, C,c, D,d Thus, smallest plant = aabbccdd=2feet tallest plant = AABBCCDD=10 feet (total 8 dominant alleles) Contribution of each dominant alleles =extra height/total no. of contributing alleles =(10-2)/8 =8/8 =1 feet/allele Cross1: aabbccdd with AABBCCD F1: all AaBbCcDd Height = (base height + contribution of each 4 dominant alleles) =2+4 =6 feet Cross 2: F1 with F1, i.e. AaBbCcDd with AaBbCcDd Let us make individual punnett square for each locus:
Possible genotype for a height of 8 feet will need 6 contributing alleles (6 dominant alleles). Thus possible genotypes are:
On adding up all the values , we will get, 1/64+1/64+1/64+1/64+4/64+4/64+4/64+4/64 20/64 |
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Ans1: 20/64 |
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Ans2: 1 feet/allele (solved above) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Answer 3: |
Given: TT=168 individuals Tt=249 individuals tt=85 individuals Total individuals = 502 Frequency of T allele =No. of T alleles/ total alleles =(168×2)+(249×1)/(2×502) =(336+249)/1004 =585/1004 =0.58266 |
Ans:Frequency of T allele = 0.59 |