Question

SHOW YOUR WORK!!

1. In zinnia plants, purple flowers plants X blue flowering plants yield 54 purple and 62 blue offspring.

However crossing blue flowering plants X blue flowering plants yield ONLY blue flowering plants.

a)What does this tell you about the genotypes of the blue and purple flowered plants?

b)Which of the alleles is dominant?

1. Mice can have normal tails or ‘bent’ tails. “Bent” is the dominant x- linked allele (B). The normal allele (b) is recessive.

A normal-tailed female is mated to a bent-tailed male.

What are the genotypes AND phenotypes of their 3 male and 5 female offspring?

Answer 1

1.

Blue × purple = purple and blue progenies

Blue × blue = blue progenies only

A. For the first case, blue is bb and purple is Bb.

For the second case, both the parents will be bb.

B. Blue is recessive over purple. B is dominant over b. Thats why, all the progenies in second case are blue.

2.

Bent = XBXB, XBXb, XBY

Normal = XbXb, XbY

XbXb × XBY

Gametes	XB	Y
Xb	XBXb bent tailed female	XbY normal tailed male

All the progenies will have phenotype and genotype given in the table.

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