VerifiedHint: The sex determining ratio or X:A ratio is the ratio between the number of X chromosomes (which is denoted by the alphabet X) and the number of sets of autosomes ( which is denoted by the alphabet A) in an organism. This ratio was used primarily for determining the sex of some species, such as drosophila flies.
Complete Answer:
- This type of ratio is carried out on the basis of genic balance theory which was proposed by Bridge to carry out the process of sex determination especially in drosophila.
- If X:A ratio comes out to be one, the offspring whose sex is being determined is a female. If X:A ratio comes out to be 0.5 then the offspring whose sex is being determined is a normal male. If this ratio ranges between 0.5 and 1 then this is the case of intersex. Whereas if this ratio exceeds 1, it will be a super female.
- In the above question the mentioned ratio is 1.5. On the basis of understanding of this description let us evaluate all the options.
1) Option A is Male. This cannot be the correct answer because to be a normal male the required ratio is 0.5.
2) Option B is female. This also cannot be the correct answer as the ratio required to be a female is 1.
3) Option C is super female. When the ratio exceeds 1, it is a case of super female. And therefore, this will be the correct option.
4) Option D is intersex. The correct answer because the ratio is not lying between the values of 0.5 and 1.
Hence, option ‘C’ will be the correct answer.
Note:
- Genic balance theory suggested that the X chromosomes carry factor for femaleness whereas the autosomes “A” are responsible for carrying genes for maleness.
- And ultimately, Y chromosome does not takes part in the sex determination.
- The genic balance was governed by the ratio of the number of X-chromosomes to the number of sets of autosomes in the zygote at fertilization.
