In Drosophila, the genes for body coloration and eye size are on different chromosomes.Normal-colored bodies are dominant to ebony-colored (very dark) bodies, and normal-sized eyes are dominant to being eyeless.Line A is true breeding for normal body and normal eye, whereas line B is true breeding for ebony bodies and being eyeless.From a dihybrid cross between lines A and B, 400 flies are scored.How many F₂ flies are expected to have ebony-colored bodies and normal eyes? A) 9 B) 25 C) 75 D) 225 E) 300

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Given that the traits are on different chromosomes and follow Mendelian inheritance, a dihybrid cross between homozygous parents (one with dominant traits and the other with recessive traits) will result in a 9:3:3:1 phenotypic ratio in the F2 generation. The question asks for the number of offspring with ebony-colored bodies and normal eyes, which corresponds to the 3/16 portion of the 9:3:3:1 ratio. Therefore, out of 400 flies, 3/16 * 400 = 75 flies are expected to have ebony-colored bodies and normal eyes.

In Drosophila, the Genes for Body Coloration and Eye Size