Describe the flow of air through the respiratory system.

Diaphragm contracts, which increases volume of thorax as ribs/ lungs move up and out.
Pressure decrease draws air into the lungs (through mouth, trachea, bronchi, bronchioles into alveoli.)
Useful gases (Oxygen) are absorbed into the blood through diffusion in alveoli.
Harmful gases in blood (CO2) diffuse across alveoli to be breathed out.
Diaphragm relaxes which causes volume of thorax to decrease, which pushed air out through the mouth.

Gravitational force i believe

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.