Vernier Software and Technology
Vernier Software & Technology

Osmosis

Figure from experiment 1B from Advanced Biology with Vernier

Introduction

In order to survive, all organisms need to move molecules in and out of their cells. Molecules such as gases (e.g., O2, CO2), water, food, and wastes pass across the cell membrane. There are two ways that the molecules move through the membrane: passive transport and active transport. While active transport requires that the cell uses chemical energy to move substances through the cell membrane, passive transport does not require such energy expenditures. Passive transport occurs spontaneously, using heat energy from the cell's environment.

Diffusion is the movement of molecules by passive transport from a region in which they are highly concentrated to a region in which they are less concentrated. Diffusion continues until the molecules are randomly distributed throughout the system. Osmosis, the movement of water across a membrane, is a special case of diffusion. Water molecules are small and can easily pass through the membrane. Other molecules, such as proteins, DNA, RNA, and sugars are too large to diffuse through the cell membrane. The membrane is said to be semipermeable, since it allows some molecules to diffuse through but not others.

In this experiment, you will use a Gas Pressure Sensor to measure the rate of pressure change as water moves in to or out of the cell (dialysis tubes filled with various concentrations of sucrose solution). The pressure generated is called osmotic pressure and is in response to the overall movement of molecules, both water and sucrose, inside the dialysis cell.

Objectives

In this experiment, you will

  • Investigate the relationship between various non-polar molecular solutions and distilled water separated by a semi-permeable membrane using a Gas Pressure Sensor.
  • Determine the water potential of potato cells.

Sensors and Equipment

This experiment features the following Vernier sensors and equipment.

Option 1

Option 2

Additional Requirements

You may also need an interface and software for data collection. What do I need for data collection?

Standards Correlations

See all standards correlations for Advanced Biology with Vernier »

Advanced Biology with Vernier

See other experiments from the lab book.

1ADiffusion through Membranes
1BOsmosis
2AEnzyme Action: Testing Catalase Activity
2BEnzyme Action: Testing Catalase Activity
3Mitosis & Meiosis
4APlant Pigment Chromatography
4BPhotosynthesis
5ACell Respiration (CO2 and O2)
5BCell Respiration (CO2)
5CCell Respiration (O2)
5DCell Respiration (Pressure)
6ApGLO™ Bacterial Transformation
6BAnalysis of Precut Lambda DNA
6BForensic DNA Fingerprinting
7Genetics of Drosophila
8Population Genetics and Evolution
9Transpiration
10ABlood Pressure as a Vital Sign
10BHeart Rate and Physical Fitness
11Animal Behavior
12ADissolved Oxygen in Water
12BPrimary Productivity
13The Visible Spectra of Plant Pigments
14Determination of Chlorophyll in Olive Oil
15Enzyme Analysis using Tyrosinase
16Introduction to Neurotransmitters using AChE
17Macromolecules: Experiments with Protein

Experiment 1B from Advanced Biology with Vernier Lab Book

<i>Advanced Biology with Vernier</i> book cover

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