Which of the following membranes would be directly involved in protecting the embryo from waste build-up? a. endoplasmic reticulum b. amnion c. allantois d. mitochondrial e. chorion

Ivan is looking at a cross section of a stem taken from a vascular plant. he sees two different types of vascular tissue: the xylem, which is closer to the center of the stem, and the phloem, located around the xylem, closer to the outside of the stem. how do these two structures work together in a living plant?

Which of the following factors would not contribute to allopatric speciation? a) a population becomes geographically isolated from the parent population.b) the separated population is small, and genetic drift occurs.c) the isolated population is exposed to different selection pressures than the ancestral population.d) different mutations begin to distinguish the gene pools of the separated populations.e) gene flow between the two populations is extensive.

The ultimate purpose of respiration: a. inhale 02 and exhale co2 b. place oxygen in the lungs c. place oxygen in the blood d. deliver oxygen to every blood cell