In Drosophila, the sex is determined by
Correct answer: C. The ratio of pairs of X-chromosomes to the pairs of autosomes
- A. The ratio of number of X-chromosome to the sets of autosomes
- B. X and Y chromosomes
- C. The ratio of pairs of X-chromosomes to the pairs of autosomes
- D. Whether the egg is fertilized or develops parthenogenetically
Explanation
In Drosophila, the sex determination mechanism involves the X/A ratio, where a specific ratio of X-chromosomes to autosomes determines the sex of the individual. A 0.5 X/A ratio results in males (XY), and a 1.0 X/A ratio results in females (XX). This mechanism differs from many other species, such as humans, where sex is determined by specific sex chromosomes (X and Y) rather than a ratio.
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About Inheritance
Mendel's laws explain segregation, independent assortment and the prediction of genetic ratios using alleles, genotypes and phenotypes. The chapter also covers linked genes, recombination and crossing over during meiosis, then applies pedigree reasoning to X-linked recessive traits, which show different inheritance patterns in males and females.
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