Question

A cross has been set up between a true breeding tall plant producing white flowers and a true breeding short plant producing red flowers. One can be certain that this type of a cross: will result in a 3 red: 1 white ratio will result in all red F_1 flowers cannot produce progeny because the parental phenotypes are different from one another is a monohybrid cross is a dihybrid cross In humans, free earlobes (E) are dominant to attached earlobes (c). If a heterozygous individual mates with an individual with attached earlobes, what proportion of their progeny is expected to have free earlobes? 0% 25% 50% 75% 100% How many Barr bodies do you expect to find in somatic cells of a healthy male and an individual with 47, XXX. 1, 3 0, 1 2, 3 1, 2 0, 2 A person with 47, XX + 21 represents an example of monosomy triploidy polyploidy ancuploidy euploidy Draw the chromosome arrangement at metaphase I and metaphase II as it would occur during spermatogenesis in an animal. Assume that somatic cells of this animal have 2n = n. Clearly label chromosome chromatids, centrosomes and spindle fibers. Different chromosome types can be distinguished based on the position of the A acrocentric chromosome has arms (state the number). Sketch an example of such chromosome? What do the following symbols mean? Explain in detail.

Answer 1

12. E. Dihybrid cross.

Cross involving two pairs of contrasting characters.

13. C. 50%.

Ee x ee

Ee, ee

Free earlobes Fused earlobes

14. E. 0,2.

Number of Barr bodies is equal to N-1, where N is total number of X chromosomes in somatic cells. So males with only one X chromosome have no Barr bodies. XXX female have 3 X chromosomes therefore no.of Barr bodies = 3-1= 2.

15. C. Aneuploidy.

Lossor addition of one or more chromosomes is called as Aneuploidy.