1. What I learned was that membranes are not only cell dividers but also regulte the transport of substances across the boundary, allowing only certain substances to pass. Membranes are fluid like and not rigid sheets. Phospholipids form a phospholipid bilayer which is two layers of molecules that surround the organelle or cell. The proteins perform most of the membranses specific functions.Also transport proteins help move certain substances across the membrane. Molecules are constantly in motin, a result of this is diffusion. A selectively permeable membrane allows some substances to cross the membrane more easily than others and blocks the passage of some substances altogether. Facilitated diffusion is when transport proteins provide a pathway for certain molecules to pass. Diffusion across a membrane is caleld passive transport because no energy is expended by the cell. An isotonic solution is when the concentration of solute in a solution are equal. Hypertonic is a solution with a higher concentration of solute, and Hypotonic is a solution with a lower concentration of solute. In animal cells, in a hypotonic solution the cells gain water, swell and may even pop. In a hypertonic solution the cells lose water and shrivel and may die. A plant cell is firm and healthiest in a hypotonic environment. A plant cell in an isotonic environment it becomes limp. In a hypertonic environment a plant cell loses water and it dies. Active transport is when the cell expends energy to move molecules across the membrane. Large particles depend on vesiciles to get into out of and within a cell.
2. What i have found difficult to understand is the process of Osmosis. I get the definitions of hypertonic, hypotonic, and isotonic. But i dont understand the result of osmosis when it involves hypertonic, hypotonic and isotonic.
3. Living organisms utilize energy to do work by Active transport,when a cell expends energy to move molecules across the membrane. During Actve transport a specific transport protein pumps a solute across a membrane usually in the opposite direction to the way it travels in diffusion.
