LAB 1
Diffusion,Osmosis and their
connection to transpiration in plants
Big Idea 2: Cellular Processes:
Energy and Communication
What causes my plants to wilt if I forget to water them?
Please be sure you have read the
student intro packet before you do
this lab. (If needed, the student intro packet is available at
www.qualitysciencelabs.com/AdvancedBioIntro.pdf)
Lab Investigations Summa
...[Show More]
LAB 1
Diffusion,Osmosis and their
connection to transpiration in plants
Big Idea 2: Cellular Processes:
Energy and Communication
What causes my plants to wilt if I forget to water them?
Please be sure you have read the
student intro packet before you do
this lab. (If needed, the student intro packet is available at
www.qualitysciencelabs.com/AdvancedBioIntro.pdf)
Lab Investigations Summary
Pre-lab Questions
Lab Investigation 1.1: Surface Area and
Cell Size How does cell size affect diffusion rates?
Lab Investigation 1.2
Part 1 - Modeling Diffusion and Osmosis
Part 2 - Observing Osmosis
Observing osmosis in living water plant cells
Part 3 - Student Guided Inquiry
Determining water potential in plant tissues
Copyright © 2013 Quality Science Labs, LLC
1
LAB 1 - Diffusion, Osmosis and their
connection to transpiration in plants
Big Idea 2: Cellular Processes: Energy and
Communication What causes my plants to wilt if I forget
to water them?
BACKGROUND
All living organisms have certain requirements they must satisfy in
order to remain alive. These mechanisms include exchanging gases
(usually CO2 and O2), taking in water, minerals, and food, and eliminating
wastes. These tasks ultimately occur at the cellular level, and require that
molecules move through the membrane that surrounds the cell. This is a
key mechanism in the cell’s ability to maintain homeostasis. Movement is
regulated because these membranes are semi-permeable, complex
structures that are responsible for separating the contents of the cell from
its surroundings, for controlling the movement of materials into and out of
the cell, and for interacting with the environment surrounding the cell.
There are two ways that the molecules move through the membrane:
passive transport and active transport. Active transport requires that
the cell use energy that it has obtained from food (Adenosine-5'-
triphosphate or ATP) to pump proteins against the concentration gradient
i.e., from low to high concentration. In eukaryotic cells, amino acids,
sugars and lipids need to enter the cell by protein pumps which require
active transport. This maintains equilibrium. Paramecium are single celled
eukaryotes with contractile vacuoles to pump out excess water. Passive
transport does not require such an energy expenditure and occurs
spontaneously. Diffusion and osmosis are both types of passive transport.
The principle mechanism of passive transport is diffusion. Diffusion
is the movement of molecules from a region in which they are highly
concentrated to a region in which they are less concentrated. It
depends on the motion of the molecules and continues until the system in
which the molecules are found reaches a state of equilibrium, which
means that the molecules are randomly distributed throughout the system.
[Show Less]