Question

it. diffusion is random movements of particles and requires no energy on the part of the cell. therefore, diffusion through a cell membrane is passive and is referred to as passive transport. for example, the cell is in constant need for oxygen to burn food for energy. because of this, the cell uses all of the oxygen molecules as soon as they enter the cell creating an inner cell environment where there is less oxygen molecules present than outside the cell. the cell is passive here because it does not use energy and it lets diffusion happen. particles can also diffuse out of the cell such as in the case of carbon dioxide (co2) waste. define the term diffusion:__ define the term concentration: what is a concentration gradient? when does diffusion stop? what does it mean when a solution has reached its equilibrium? why is diffusion a type of passive transport?__ facilitated “helped” transport (diffusion): station three: facilitated diffusion (“helped”) instruction: read the below information provided and answer the following questions at the end of the text. the cell membrane is selectively permeable, meaning it allows only certain molecules to pass through easily. the simplest example of a cell membrane is a soap bubble. have you ever seen the colors swirl on a bubble? both bubbles and cells are fluid, meaning molecules move around constantly on its surface. many smaller molecules like water, oxygen and carbon dioxide can easily pass straight through the cell/plasma membrane without harming it. the membrane has strong forces that hold the membrane together and seal it up whenever molecules pass through it. the membrane is still fragile though. the cell must have water inside and outside the cell; not only to dissolve materials needing to be transported through the membrane, but to hold the membrane together itself. larger molecules such as glucose and amino acids, are unable to pass through the membrane easily. to facilitate or “help” these molecules across the membrane, bridges are used to carry them across. these bridges are transport proteins called protein channels or pores. this type of diffusion is called facilitated diffusion because movement of the molecules is “helped” across the membrane by these transport proteins. most of these proteins are specific, allowing only certain molecules to pass. this is similar to the idea of a pet door. the pet can pass through the door to get into and out of the house, but i doubt very seriously that you could crawl through the pet door. this choosy characteristic of the membrane is called selectively permeable.

Explanation:

1. Diffusion: Random movements of particles that require no energy from the cell for transport across a membrane.
2. Concentration: The amount of a substance (such as molecules) in a given volume.
3. Concentration gradient: The difference in the concentration of a substance between two areas.
4. Diffusion stops when equilibrium is reached, i.e., when the concentration of the substance is the same throughout the space.
5. A solution has reached equilibrium when the concentration of the solute is evenly distributed throughout the solution and there is no net movement of particles.
6. Diffusion is passive transport because it does not require the cell to expend energy; it relies on the random motion of particles.
7. Facilitated diffusion is the movement of larger molecules (like glucose and amino - acids) across the cell membrane with the help of transport proteins (protein channels or pores) down their concentration gradient.

Answer:

Define the term diffusion: Random movements of particles requiring no cell - energy for membrane transport.
Define the term concentration: Amount of a substance in a given volume.
What is a concentration gradient? Difference in substance concentration between two areas.
When does diffusion stop? When equilibrium is reached (same concentration throughout).
What does it mean when a solution has reached its equilibrium? Solute concentration is evenly distributed with no net particle movement.
Why is diffusion a type of passive transport? Does not require cell to expend energy, relies on particle random motion.
Facilitated “helped” Transport (Diffusion): Movement of larger molecules across membrane with transport - protein help down concentration gradient.