Yakima WATERS Mini Lesson
Osmoregulation in an Aquatic Plant
Targets and Assessment
WA Science Standards Addressed:
 9-12 INQB Investigate
 9-11 LS1D
Lesson Parameters
Content Area: Biology
The purpose of this lab is to illustrate
diffusion and osmosis in an elodea leaf by varying
environmental solute concentration.
Overview:
Grade Level: 10
Assessments:
 Rubric
Suggested Time: 55-75 minutes
Special Materials:
 Prepare a 6% solution of sodium chloride and water
 Elodea plant, Elodea canadensis
Learning Outcomes:
Knowledge: Students should be able to answer questions about the process of osmoregulation and its
role in maintaining homeostasis. Students should also be able to explain the different features of a
microscope and a slide.
Skill: General microscope technique, slide preparation, and diagramming important details of an
observation
Science Concept Background:
Changes in solute concentration in an aquatic environment will affect an aquatic plants ability to
maintain osmotic balance. This lab requires prior knowledge of homeostasis and osmoregulation.
Materials:
Microscope
Microscope slides
cover slips
medicine droppers
elodea or equivalent aquatic plant
Water
6% salt solution
Procedure:
1. Students prepare two wet slides of an elodea leaf in tap water and an elodea leaf in salt water for
microscopic observation.
2. Study each slide under a microscope and note the differences and similarities between them.
2. Students should make detailed diagrams of their observations.
3. Students should observe differences in elodea cells experiencing osmotic balance and imbalance.
4. Students should be able to thoughtfully answer the following questions:
What effect did altering the solute concentration of the water have on the elodea leaf cells?
Did the organelle arrangement change?
Which slide did you observe osmotic balance? Which slide did you observe osmotic
imbalance?
What is the real world application of this exercise?
What do the results tell us about what we put in our watershed and the impact on our biotic
community?
These questions may be directly presented to the students or maybe used as a guideline for a lab
report.
CATEGORY
Participation
4
Used time well in
lab and focused
attention on the
experiment.
3
Used time
pretty well.
Stayed
focused on
the
experiment
most of the
time.
Demonstrated
very good
microscope
and slide
technique.
Willing to help
others
2
Did the lab but did
not appear very
interested. Focus
was lost on
several occasions.
1
Participation was
minimal OR
student was
hostile about
participating.
Lab
Equipment
Demonstrated
excellent
microscope and
slide technique.
Helped others
when necessary
Demonstrated
sufficient
microscope and
slide technique.
Did not help
others.
Demonstrated
poor microscope
and slide
technique.
Required
constant help
from others
Conclusion
(In terms of
answers to
the
questions
posed)
Conclusion
includes whether
the findings
supported the
hypothesis,
possible sources
of error, and what
was learned from
the experiment.
Conclusion
includes
whether the
findings
supported the
hypothesis
and what was
learned from
the
experiment.
Conclusion
includes what was
learned from the
experiment.
No conclusion
was included in
the report OR
shows little effort
and reflection.
Scientific
Concepts
Answers illustrate
an accurate and
thorough
understanding of
scientific
concepts
underlying the
lab.
Answers
illustrate an
accurate
understanding
of most
scientific
concepts
underlying the
lab.
Answers illustrate
a limited
understanding of
scientific concepts
underlying the lab.
Answers illustrate
inaccurate
understanding of
scientific
concepts
underlying the
lab.
Author: Jack Lester, Yakima WATERS Project, CWU, Fall 2009