Algae (the seaweeds)
Open the “A look at the algae” PowerPoint. Use the PowerPoint and the algae article found at
your station to answer the following questions.
Observe any other resources found at your station.
1. What is meant by “primitive plant”?
A primitive plant is a plant that does not have true roots, stems and
2. Why is the word “algae” confusing?
The word algae is confusing because biologists use the term to
describe many different groups that are not related to one another.
3. What is a thallus?
A thallus is the plant body of an alga. It contains no vascular tissue
and is not separated into roots, stems, or leaves.
4. What is a holdfast?
A holdfast is the lowermost cell of a thallus filament that anchors the
filament to rocks or mud.
5. List a few places you might go to find algae.
Fast-flowing streams, lakes, quiet ponds, drainage ditches, near
shores, tidal zones
6. In what ways are algae important to us?
Algae supply oxygen through photosynthesis.
7. What four (4) characteristics do biologists use to classify algae into
(ii) type of storage product in the cells
(iv) structure of the thallus
8. What is the difference between isogametes and heterogametes?
Isogametes are when the sperm and egg cells are alike in size and
Heterogametes are when the sperm and egg cells are different in size
9. What are three (3) asexual methods of reproduction in algae?
10. What is a zoospore?
A zoospore is a small reproductive cell with at least two flagella.
11. What types of plant bodies are found in green algae?
Chlorophylls and other pigments that store starch in their cells.
12. Why do biologists think that ancient green algae were the ancestors of
Algae also store starch (like true plants!!) and contain the same
pigments as green algae.
FILL IN THE CHART BELOW USING THE ALGAE POWERPOINT
Common name Phylum Name Characteristics (list…)
Most abundant & widely distributed of
Chlorophyta unicellular & multicellular
approx. 6000 species
contain cholorphylls (like higher plants)
store starch in their cells (like higher
Believed higher plants evolved from
Many species grow in cool waters along
rocky coasts (anchored to rocks by their
Phaeophyta root-like parts & gas-filled structures
that function as floats ).
important source of iodine.
Can be used as fertilizer or as food for
humans.Other species are a source of
algin, which is used to thicken ice crème
and other foods.
Multicellular but never as large as the
largest brown algae
Rhodophyta More complex that other forms of algae
Most live in salt water but in warmer
waters and greater depths
Very beautiful colors (red, green, yellow,
Cell walls contain cellulose as well as
other substances like agar (thickener in
foods like ice crème, puddings, and cake
icing; medium on which bacteria and
fungi are grown in laboratories)
Carrageenan is another product of red
algae which is a type of stabilizing agent
used to prevent separation of food
mixtures (i.e. chocolate and milk)