Simple Diffusion Across the Cell (Plasma) Membrane. The structure of the lipid bi-layer allows small, uncharged substances such as oxygen and carbon dioxide, and hydrophobic molecules such as lipids, to pass through the cell membrane, down their concentration gradient, by simple diffusion.
Answer:
Stem cells are primal cells found in all multi-cellular organisms. They retain the ability to renew themselves through mitotic cell division and can differentiate into a diverse range of specialized cell types.
Explanation:
In adult organisms, stem cells and progenitor cells act as a repair system for the body, replenishing specialized cells.
B is false, enzymes speed up the reaction by lowering the activation energy needed for the reaction to start.
Answers B
The Answer is D
Without a host, a virus is basically inert and useless. They cannot function outside a host organism.
