What accurately describes physical barriers? i. they are difficult for bacteria and viruses to penetrate. ii. they include the skin and the mucous membranes. iii. they may work in conjunction with secretions like tears and mucus?

Apaleontologist finds a plant fossil that shows that the plant had seeds. what can the paleontologist conclude?

One of the newest applications of cell technology is called cybrid embryos. this process involves replacing the nuclear material of an animal cell with human nuclear material. how might this process affect public policies about research by using stem cells? the same policies and concerns about the use of human embryonic stem cells would most likely apply. the embryos would most likely be treated like traditional animal embryos and regulated accordingly. the process of forming cybrid embryos would most likely be banned by government regulators. the embryos would be treated as regular cells because they are not fully human in origin.

The solution inside a plant cell is approximately a 1% saline solution and a 21% nacl solution the ,cytoplasm of a plant cell will