2. If having blue eyes is a recessive trait, answer the following questions: a)

Question

2. If having blue eyes is a recessive trait, answer the following questions: a) Couldparents with dark eyes have children with blue eyes? b) Could parents with blue eyes have children with dark eyes? 3. Crossing two drosophila flies (both) with normal wings produces 27 individuals with short wingsand 79 with normal wings. a) How is the short wings trait transmitted? b) What are the parents genotypes? c) If flies with short wings are crossed with one of the parent flies, how many normal flies are expected in an offspring of 120 flies? 2. If having blue eyes is a recessive trait, answer the following questions: a) Couldparents with dark eyes have children with blue eyes? b) Could parents with blue eyes have children with dark eyes? 3. Crossing two drosophila flies (both) with normal wings produces 27 individuals with short wingsand 79 with normal wings. a) How is the short wings trait transmitted? b) What are the parents genotypes? c) If flies with short wings are crossed with one of the parent flies, how many normal flies are expected in an offspring of 120 flies? 2. If having blue eyes is a recessive trait, answer the following questions: a) Couldparents with dark eyes have children with blue eyes? b) Could parents with blue eyes have children with dark eyes? 3. Crossing two drosophila flies (both) with normal wings produces 27 individuals with short wingsand 79 with normal wings. a) How is the short wings trait transmitted? b) What are the parents genotypes? c) If flies with short wings are crossed with one of the parent flies, how many normal flies are expected in an offspring of 120 flies?

Explanation / Answer

2. The blue eyes is a recessive trait so genotype of blue-eyed individual will be rr.

a) Yes, parents with dark eyes have children with blue eyes if the cross is between Rr X Rr.(both dark-eyed) produce progeny with genotype - RR, Rr, Rr, rr. Here, rr genotype carrying offspring will be blue-eyed but other genotypes will be of dark-eyed children.

b) Yes, parents with blue eyes have children with dark eyes i.e. 3:1 means more of dark-eyed and rests with blue-eyed as shown in answer a).

3. Normal winged X Normal winged = 27 short-winged + 79 normal wings.

Total = 106 Drosophila.

a) Normal winged = WW or Ww

Here 'W' is for normal wings which is dominant over short wings 'w'. So, if there is a cross between Ww and Ww(both normal winged) we get offsprings: WW, Ww and ww. The phenotypic ratio will be 3:1 means more Normal winged along with few short-winged drosophilas will be there in F1 generation.

b) Parents genotype will be Ww.

c) Ww X ww we will get offsprings with genotype Ww and ww only means if total offsprings are 120 then 50% will be normal (Ww) and 50% will be with short-winged(ww).

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