Are there any parts of the human body that get oxygen directly from the air and not from the blood?

In familial hypercholesterolemia individuals homozygous for the allele causing the disorder completely lack receptors on liver cells that take up cholesterol from the blood stream. heterozygous have one-half the number of receptors while individuals homozygous for the normal allele are phenotypically normal. this is an example of a.epistasis b.complete dominance c. incomplete dominance d. codominance

What environmental cues and landmarks do the geese use to determine the timing and direction of their migration over the mountains? how do they find their way?

10. in which phase will crossing-over occur? a. mitosis b. metaphase ii c. prophase i d. meiosis ii