1. In Drosophila, the genes for body coloration and eye size are on different chromosomes. Normal-colored...

1. In Drosophila, the genes for body coloration and eye size are on different chromosomes. Normal-colored bodies are dominant to ebony-colored bodies, and normal-sized eyes are dominant to eyelessness. Line A is true breeding for normal bodies and normal eyes, while line B is true breeding for ebony bodies and eyelessness. F1 flies are crossed and 352 F2 flies are produced. How many F2 flies are expected to have ebony body color and to be eyeless?

2. What is the probability that a plant of genotype ccWw will be produced from parental plants of the genotypes CcWw and Ccww? Assume that the two gene pairs demonstrate simple dominance/recessiveness and that they assort independently.
Type your answer as a decimal fraction with 3 significant figures (0.XXX).

3. Assume you cross dihybrids of Pisum sativum: R/r (round seeds) and P/p (purple flowers). If you obtain 328 plants from that cross, what would be the expected number of plants that would have the genotype: R/r, P/p?

Expert Solution

1) let the alleles be

E- normal body colour, e- ebony body colour, S- normal-sized eye, s- eyeless

normal eyes, normal body colour * eyeless, ebony body colour

EESS * eess

EeSs ( F1)

EeSs * EeSs

	ES	Es	eS	es
ES	EESS ( normal eyes and body colour)	EESs ( normal eyes and body colour)	EeSS ( normal eyes and body colour)	EeSs ( normal eyes and body colour)
Es	EESs ( normal eyes and body colour)	EEss (normal body colour, eyeless)	EeSs ( normal eyes and body colour)	Eess (normal body colour, eyeless)
eS	EeSS ( normal eyes and body colour)	EeSs ( normal eyes and body colour)	eeSS (ebony body colour, normal eyes)	eeSs (ebony body colour, normal eyes)
es	EeSs ( normal eyes and body colour)	Eess (normal body colour, eyeless)	eeSs (ebony body colour, normal eyes)	eess ( ebony body, eyeless)

the proportion of ebony body and eyeless= number of ebony body and eyeless/total number=1/16

so expected number of ebony body and eyeless = proportion of ebony body and eyeless total number

= 1/16352

= 22

expected number of ebony body and eyeless = 22

gladiator answered 6 months ago

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