Question
Question: According to genic balance theory X/A = 1.5 will make the individual A)Male B)Meta or Super fema...
According to genic balance theory X/A = 1.5 will make the individual
A)Male
B)Meta or Super female
C)Intersex
D)None of the above
Solution
The Calvin Bridges 1926 theory of genic balance notes that sex is determined instead of XY chromosomes by the genic equilibrium or ratio between X-chromosomes and autosome genomes.
Complete answer:
Genic balance Theory has been suggested by C. B. Bridges in 1922, in Drosophila for sex determination. It states that the sex of Drosophila is determined by the ratio of the X-chromosome number to that of the complete autosome set.
If the ratio of the X chromosome to the total number of autosome sets (X/A) is > 1, the organism will be a super female according to this sex-determination theory.. The intersex phenotype is indicated by the genotype if the ratio of the X chromosome to the total number of autosomal sets (X/A) falls between 1 and 0.50. For normal females, the X/A value is 1.0, and for normal males, 0.5.
It shows clearly that genes that tend to maleness and X chromosomes carry genes that tend to fema are Drosophila autosome bear
According to the theory of the genetic balance:
Gene ratio (X/A) of 1.0 produces fertile females.
Genic ratio (X/A) of 0.5 is a productive male.
Genic ratio less than 0.5 produced infertile meta-males (super males).
Sterile meta-females (super-females) are produced with a gene ratio of 1.5.
Sterile meta-females (super-females) are produced with a gene ratio of 1.5 (3X/2A). Dodson called the sterile meta-males and meta-females the glamorous boys and girls of the flying world
| Chromosome Complement | X / A Ratio | Sexual Morphology |
|---|---|---|
| X X X + 2A | 3/2 or 1.5 | Metafemale |
| X X X + ЗА | 3/3 or 1.0 | Female |
| XX + 2A | 2/2 or 1.0 | Female |
| X X + ЗА | 2/3 or 0.67 | Inter sex |
| X X X + 4A | 3/4 or 0.75 | Inter sex |
| XO + 2A | 1/2 or 0.5 | Male |
| XY + 2A | 1/2 or 0.5 | Male |
| XY + ЗА | 1/3 or 0.33 | Metamale |
Hence, the correct answer is option (B)
Note: All individuals carry the gene for both male and female sex. But it is actually the relationship between the X-chromosome and the autosome that governs the development of male or female sex. Ratio is known as sex index ratio. However, this genetic gender balance theory does not apply to humans or mammals, and also to those individuals where Y chromosomes play a role in sex determination.