On which of the following phases does nondisjunction occur?

What could be causing the large differences in various traits between you and your sibling?

Two genes of a flower are linked and are 20 map units apart. One gene controls height (T = tall vs. t = dwarf) and the other controls the flower color (P = purple vs. p = white). A homozygous tall plant with white flowers is crossed with a homozygous dwarf plant with purple flowers and the resulting F1 progeny is crossed with homozygous dwarf plants with white flowers. If the F2 progeny has 100 plants, which of the following correctly shows the number of plants with each of the four possible phenotypes?

Genes for eye colour and wing size of Drosophila are located on the same chromosome. A wild-type Drosophila heterozygous for both eye colour and wing size is mated with a Drosophila which is homozygyous recessive at both the loci. Which of the following accurately depicts the percentage of offsprings with recombinant phenotypes?

To determine the order of body colour, wing size and eye colour genes on the chromosome of Drosophila, which of the following sets of crosses will you perform?

a. Cross 1 - ♂ wild-type heterozygous for normal wings and red eyes x ♀ recessive homozygous for vestigial wings and purple eyes. Cross 2 - ♂ wild-type heterozygous for gray body and red eyes x ♀ recessive homozygous for black body and purple eyes.

b. Cross 1 - ♂ wild-type homozygous for normal wings and red eyes x ♀ recessive homozygous for vestigial wings and purple eyes. Cross 2 - ♂ wild-type homozygous for gray body and red eyes x ♀ recessive homozygous for black body and purple eyes.

c. Cross 1 - ♂ wild-type heterozygous for normal wings and red eyes x ♀ recessive homozygous for vestigial wings and purple eyes. Cross 2 - ♂ wild-type homozygous for gray body and red eyes x ♀ recessive homozygous for black body and purple eyes.

d. Cross 1 - ♂ recessive homozygous for vestigial wings and purple eyes x ♀ recessive homozygous for vestigial wings and purple eyes. Cross 2 - ♂ recessive homozygous for black body and purple eyes x ♀ recessive homozygous for black body and purple eyes.

In a hypothetical organism, coat colour, wings and height are inherited in the same way that they are in humans. The two alleles for coat colour of the organism are: B = brown, b = white; for its wings are: W = normal wings, w = vestigial, and for its height are: T = tall, t = dwarf. A researcher carried out two types of breeding experiments (BE) in the laboratory and obtained the following results.

What is the recombination frequencies for BE1 and BE2?

A wild-type Drosophila which is heterozygous for gray body and normal wings is mated with a Drosophila with black body and vestigial wings. The phenotypic distribution of the offspring is as follows: wild-type - 1556, black with vestigial wings - 1570, gray with vestigial wings - 324, black with normal wings - 316. What will be the recombination frequency between the genes for body colour and wing size?