osmosis, solutions, and transportation

How Organisms Deal with Osmotic Pressure

Bacteria and plants have cell walls that prevent them from them from bursting when taking in water.

A protist like paramecium has contractile ____ that collect water flowing in and pump it out to prevent them from ______.

vacuoles, over expanding

Salt water fish pump salt out of their specialized gills ______

so they do not dehydrate.

Animal cells are bathed in_____ Kidneys keep the blood ______by remove excess _____ and ______.

blood, isotonic, salt and water

Passive transport:

Cell doesn’t use energy (Diffusion, Facilitated diffusion, Osmosis)

Active transport:

Cell does use energy (Protein pumps, Endocytosis, Exocytosis)

Passive transport

Cell uses no energy. Molecules move randomly from an area of high concentration to an area of low concentration (High→Low). Three types: Diffusion, Facilitative Diffusion (with transport proteins), and Osmosis (diffusion of water).

Diffusion

Random movement of particles from an area of high concentration to an area of low concentration (High to Low). Continues until molecules are evenly spaced (equilibrium is reached), though molecules still move around.

Facilitated diffusion

Diffusion of specific particles through transport proteins found in the membrane. Transport proteins are specific and select only certain molecules to cross, usually transporting larger or charged molecules.

Osmosis

Diffusion of water through a selectively permeable membrane. Water moves from high to low concentrations and moves freely through pores, while solutes too large to move across remain on one side.

Active transport

Cell uses energy to actively move molecules to where they are needed. Movement is from an area of low concentration to an area of high concentration (Low → High).

Protein Pumps

Transport proteins that require energy to do work. Example: Sodium/Potassium Pumps are important in nerve responses.

Endocytosis

Taking bulky material into a cell using energy. The cell membrane invaginates (folds inward) to surround the material, forming a vacuole or vesicle that pinches off into the cell.

Exocytosis

Forcing material out of the cell in bulk. The membrane surrounding the material fuses with the cell membrane, causing the cell to change shape. Requires energy. Example: Hormones or wastes released from the cell.

Osmosis and life

Osmosis is the diffusion of water through a selectively permeable membrane. Water is so small and abundant that the cell cannot control its movement through the cell membrane.

Hypotonic solution

A solution with a lower solute concentration than the cell. Water moves into the cell, causing it to swell.

Hypertonic solution

A solution with a higher solute concentration than the cell. Water moves out of the cell, causing it to shrivel.

Isotonic solution

A solution with the same solute concentration as the cell. There is no net movement of water, and the cell maintains its shape.

Homeostasis

The state of steady internal conditions maintained by living things. In osmosis, it refers to the balance of water and salts (e.g., kidneys keeping blood isotonic).