NOTES DOSSIER

Lab 8

Cell Function: Diffusion and Osmosis

start!

Cell Transport

There are several ways that nutrients, ions, oxygen, carbon dioxide, and other molecules can be moved in and out of cells across the cell membrane. The two transport methods diffusion and osmosis

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Diffusion

The process of diffusion occurs whenever dissolved particles move from an area of higher concentration to an area of lower concentration. The rate of diffusion may be influenced by density of media, cocentration gradient, temperature, and molecular size.

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Activity

01

Diffusion of Scent

Diffusion of Scent

In this activity, a volunteer sprays a scent in front corner of the room. Start the timer When you detect the odor, stop the timer and record your time. Using a meter stick we recorded the distance from the orgin point of the scent to your position.

What variables can affect the rate of diffusion?

Distance was the main variable that can affect the rate of diffusion. If you look at the data, group 1 had a distance of 3 m with diffusion rate of 360 m/hr Whereas, group 2 had a distance of 7 m with diffusion rate of 925.915 m

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Activity

02

Understanding Osmosis

Solution and Water molecules

Understanding Osmosis

A solute is a substance that is dissolved in a liquid solvent and the resulting mixture is called a solution.

Osmosis: A process similar to diffusion occurs with water molecules in the environment. In osmosis, water molecules diffuse through a selectively permeable membrane from an area of hyptonic solution to an area of hypertonic solution.

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Tonicity

Hypertonic solution has a higher concentration of solute and less water molecules Hypotonic solution has a lower concentration of solute and more water molecules Isotonic solution has an equal concentration of solute and water molecules

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Activity

03

Osmosis - Effect of Hypotonicity and Hypertonicty in Plant Cells

Effects of diferent solution

After 15 minutes, Total Magnificatio 400x

In this activity, students examine the effects of different solutions on cell volume Three types of osmotic environments: - Isotonic - Hypotonic -Hypertonic

Tonicity inside the cell: Hyptonic Tonicity outside the cell: Hypertonic

Time "0", Total Magnification 400x

Cells in Water

Cells in 25% NaCl

Time "0" Total Magnification 400x

Cells in 25% NaCl

After "15" mins, Total Magnification 400x Tonicity inside the cell: Hypertonic Tonicity outside the cell: Hyptonic

Thank You!