Science 7
Unit 3
Living Things
Name: ______________________________
Date: ______________ Period: __________
Protista – Protists
Kingdom Protista is very diverse. However, all Protists are eukaryotes, or organisms that have
cells with nuclei.
All live in moist surroundings, Most are unicellular, bur some are
multicellular. Some are heterotrophs, some are autotrophs, and some are both. Protists can be
divided into three categories: animal-like, fungus-like, and plant-like Protists.
Animal-like Protists are also called protozoans, Like animals, animal-like Protists are
heterotrophs. Most can move from place to place to get food. Many protozoans that live in fresh
water have contractile vacuoles. A contractile vacuole is a structure that expels water that has
entered through its cell membrane. There are four types of protozoans: sarcodines, ciliates,
zooflagellates and sporozoans. Sarcodines move and feed by using pseudopods. Pseudopods are
temporary bulges of the cell membrane that fill with cytoplasm. Ciliates are covered with
hairlike projections called cilia. They use cilia to move, obtain food, and sense the environment.
Zooflagellates move using whiplike flagella. Often, zooflagellates live inside the bodies of other
organisms in a state of symbiosis. Symbiosis is a close relationship between two species where
at least one of the species benefits. Sometimes, zooflagellates harm their hosts. In other cases,
their relationship is one of mutualism, in which both the host and the zooflagellate benefit.
Sporozoans are parasites that feed on their hosts’ cells and body fluids.
Like fungi, funguslike Protists are heterotrophs, have cell walls, and use spores to reproduce.
Unlike fungi, however, all fungus like Protists are able to move at some point in their lives. The
three types of funguslike Protists are water molds, downy mildews, and slime molds. Water
molds and downy molds grow as tiny threads in water or moist places. Slime molds live in moist
soil and on decaying plants.
Plantlike Protists are called algae. The one characteristic that all algae share it that, like plants,
they are autotrophs. Algae can exist in a variety of colors because they contain many types of
pigments- chemicals that produce color. There are six types of plantlike Protists: euglenoids,
dinoflagellates diatoms, green algae, red algae, and brown algae. Euglenoids can be heterotrophs
when sunlight is not available. Dinoflagellates are covered by stiff plates and move using two
flagella. Diatoms have beautiful, glasslike cell walls. Green algae live in fresh water, salt water,
an moist places on land. Red algae and brown algae live in the oceans.
Understanding the Main Ideas
Fill in the blanks in the table below.
Type of Protist
Animal-like
3. ______________
Shared Characteristics
Examples
Heterotrophs; most move
Sarcodines, ciliates,
by using pseudopods, cilia,
zooflagellates and
or 1.__________________
2.__________________________
Heterotrophs, cells walls,
Water molds, downy mildews and
reproduce with spores
4. _________________________
Euglenoids, dinoflagellates, red
5. ______________
Autotrophs
algae, brown algae,
6.______________________, and
7.____________________
Building Vocabulary Skills
Match each term on with its definition by writing the letter of the correct definition in the right
column on the line beside the term in the left column.
_____ 8. Protozoan
a. a form of symbiosis that benefits both species
_____ 9. Pseudopod
b. an animal-like Protist
_____ 10. Spore
c. a tiny cell that is able to grow into a new organism
_____ 11. Contractile vacuole
d. a chemical that produces color
_____ 12. Cilia
e. temporary bulge of a cell membrane that fills with
cytoplasm
_____13. Algae
f. hairlike projections of ciliates that are used to capture
food, move, and sense the environment
_____ 14. Symbiosis
g. plantlike Protists
_____ 15. Mutualism
h. structure that collects excess water and expels it from a
cell
_____ 16. Pigment
i. close relationship between two species where at least one
of the species benefits