Comparing Plants and Algae
Concepts: Students will explore a misconception and use information from
observations to accurately and effectively communicate findings.
Objective: The students will observe plants and alga and compare and contrast the
two.
Summary: A common misconception exists that algae are plants. While it is true
that some algae are closely related to plants, this is not true in most cases. This
lesson will help students identify the similarities and differences between plants
and algae through careful observation.
Teacher Notes:
Equipment/Materials:
Elodea
Cladophora
Lemna (Duckweed)
Microscope
Slides
Compare/Contrast handout
Hand lens
Three domains illustration
Phylogenic Tree of Life
© 2010, Ohio Northern University: Dr. Kenneth Reid, Dr. Debra Gallagher and Dr. Robert Verb
Useful Websites:
Algae: The World’s Most Important “Plant”
http://www.youtube.com/watch?v=CB2XlpD-Ld4
Activity Sheets:
Compare/Contrast Graphic Organizer
Engage:
Show the students an illustration of the Three Domains and the Phylogenic Tree of
Life without the details. Say, “The three domain biological classification system
developed by Carl Woese include: Archae, Bacteria, and Eukaryote.” Ask the
following questions:
1. In which of these domains do you think you would find algae?
2. Which would you find plants?
3. Are algae plants?
Discuss these questions as a springboard to the investigation of plants and algae.
Explore:
1. Each pair of students will have a sprig of Elodea, duckweed, and a sample of
Cladophora to observe.
2. Begin by observing any differences you can see with the naked eye.
3. Use a hand lens to observe and record your findings.
4. Make a separate slide for the Elodea, duckweed, and Cladophora and
observe each under the microscope. Record everything you observe in your
notebook, descriptions and illustrations.
© 2010, Ohio Northern University: Dr. Kenneth Reid, Dr. Debra Gallagher and Dr. Robert Verb
Explain:
1. Hand out Algae and Plant sheet to each student.
2. Discuss findings as a class and begin to compare and contrast algae and
plants.
3. Discuss the work of Dr. Carl Woese, Three Domains , and the Phylogenic
Tree of life to examine more similarities and differences.
4. View the video, Algae: The World’s Most Important “Plant” featuring
Russell Chapman, Ph.D
http://www.youtube.com/watch?v=CB2XlpD-Ld4
5. Discuss the similarities and differences between plants and algae.
Extend:
1. Students look at two or three more samples of algae with the microscope.
2. Are the findings the same as the Cladophora?
3. Make additions or changes to Algae and Plants worksheet.
Evaluate:
1. Using the Algae and Plant worksheet, the students will write two paragraphs
comparing and contrasting plants and algae. One paragraph will describe
the similarities between algae and plants the second paragraph will describe
the differences.
Enrichment Activity:
© 2010, Ohio Northern University: Dr. Kenneth Reid, Dr. Debra Gallagher and Dr. Robert Verb
Teacher Background:
Algal Myths
1. Algae are plants.
Mostly no…but sometimes yes. The term “algae” is applied to predominately
aquatic (there are some terrestrial and subterranean species), photosynthetic
organisms that are not included in the Kingdom Plantae (bryophytes and vascular
plants). As mentioned in earlier the term “algae” is a garbage can for many
photosynthetic organisms that are not closely related to one another (or members
of the Kingdom Plantae for that matter). The matter is further cloudy by the fact
that some algae (members of the Chlorophyta) are actually closely related to
members of the Kingdom Plantae. Table 1 attempts to highlight some
differences/similarities between these groups.
Character
Photosynthetic
Hetertrophic
Habitat
Prokaryotic Cells
Eukaryotic Cells
Chloroplast
Morphology
Vascular System
Stems, Leaves, and
Roots
Stomata
Cuticle
Algae
Yes
Some
Mostly aquatic
Some (Cyanobacteria)
Most
Most
Single cells, Colonies,
Multicellular
Very few
No
No
No
Plants
Yes
No
Mostly terrestrial
No
Yes
Yes
Multicellular
Most (bryophytes do
not)
Most (bryophytes do
not)
Most
Yes
© 2010, Ohio Northern University: Dr. Kenneth Reid, Dr. Debra Gallagher and Dr. Robert Verb
Three Domains
Dr. Carl Woese