how is nitrogen obtained by animals?

a. they breathed it in from the air.
b. they get it from the soil.
c. they get it from eating plants.
d. they produce it in their chloroplasts.

Which best describes the structure of dna?

Is there any solid scientific evidence that humans have been cloned?

19. a cell is viewed under a microscope and is found to have two nuclear envelopes and spindles that appear to be breaking apart. which phase of mitosis is the cell most likely in? a. metaphase b. prophase c. telophase d. anaphase