In an eight-cell embryo of an organism, the cells of the upper tier are aligned over the cells of the lower tier at a slight angle. which organism is it likely to be? the choices are the following: earthworm. . starfish. . sea cucumber. . sea urchin.

I think the correct answer among the choices listed above is option C. The organism described most likely is a starfish. This is because annelids and mollusks exhibit spiral holoblastic cleavage while the echinoderms have radial holoblastic cleavage.

The answer would be c, white eyes are homozygous recessive. in the early 1900s, morgan conducted several experiments with vinegar  flies (drosophila). one  sample revealed an anomaly: a  white-eyed, single male fly. he attempted to breed this fly with the typical red-eyed females. the offspring were all red-eyed. using flies from this new generation (brother-sister pairs)  produced some red-eyed and a few white-eyed flies. the white-eyed were all male. in later experiments, he was able to produce white-eyed females. this proved that white eyes are not lethal to either sex (ruling out a and b). since the percentage of white eyes to red eyes is so low, white eyes are not a dominant trait. it would be a recessive trait.