Question

diffusion and osmosis worksheet
diffusion is the movement of particles from areas of higher concentration to areas of lower concentration. it is a natural, random process. this means that it does not require extra energy input.

1. these are pictures of molecules frozen at two different times. draw arrows to show the direction each particle might travel due to diffusion in diagrams a and b.
2. diagram a shows the same number of particles as in diagram b except most particles start out on one side of the box. explain why after a while, diagram a resembles diagram b.
3. give an everyday example of diffusion in air and in water.

• air:
• water:

1. complete the following sentence: diffusion is the __ movement of particles from concentration to a concentration until they are __ spread out.

word bank: passive / active / lower / higher / unevenly / evenly

1. moths emit chemicals called pheromones to attract a mate.

a) which process is responsible for the distribution of these chemicals through the air?
b) if a moth detects pheromones, how might it work out which direction they are coming from?
c) what would be the advantage of a moth releasing the pheromones on a night when there was little wind?

1. osmosis is the diffusion of water across a semi - permeable membrane. the semi - permeable membrane acts like a filter that lets only the water through. water always goes from the area of higher water concentration to the area of lower water concentration. confused? then imagine the particles (or solute) are salt and follow the rule - salt sucks!

on the diagram to the right label the:

• semi - permeable membrane (m)
• area of higher water concentration (hc)
• area of lower water concentration (lc)
• direction of osmotic flow (arrow)

Explanation:

Step1: Answer question 1

Draw arrows in Diagram A pointing from the side with more particles to the side with fewer particles to show diffusion. In Diagram B, since particles are more evenly - spread, arrows can be drawn randomly as particles are still in motion but more evenly distributed.

Step2: Answer question 2

Particles in Diagram A will move from the area of higher concentration (where they are initially clustered) to the area of lower concentration due to the random motion of diffusion until they are evenly spread out like in Diagram B.

Step3: Answer question 3

AIR: The smell of perfume spreading in a room is an example of diffusion in air. WATER: When a drop of food - coloring is added to a glass of water, the color spreads throughout the water due to diffusion.

Step4: Answer question 4

Diffusion is the passive movement of particles from higher concentration to a lower concentration until they are evenly spread out.

Step5: Answer question 5a

Diffusion is responsible for the distribution of pheromones through the air.

Step5: Answer question 5b

A moth might detect the concentration gradient of pheromones. The side with a higher concentration of pheromones is likely the direction they are coming from.

Step5: Answer question 5c

On a night with little wind, the pheromones will diffuse more predictably in a circular - like pattern from the source. This allows a potential mate to more accurately follow the concentration gradient to find the moth releasing the pheromones.

Step6: Answer question 6

Label the semi - permeable membrane (M) on the membrane in the diagram. Label the area with fewer solute particles (more water) as the area of higher water concentration (HC), the area with more solute particles (less water) as the area of lower water concentration (LC). Draw an arrow from the HC area to the LC area to show the direction of osmotic flow.

Answer:

1. Arrows drawn as per diffusion principles in Diagrams A and B.
2. Particles move from high to low concentration by diffusion to become evenly spread.
3. AIR: Perfume smell spreading in a room. WATER: Food - coloring spreading in water.
4. Passive, higher, lower, evenly.

5a. Diffusion.
5b. By detecting the concentration gradient of pheromones.
5c. Pheromones diffuse more predictably, allowing for easier detection by a mate.

1. M, HC, LC labeled correctly and arrow drawn for osmotic flow.