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6.6: Importance of Protists

Difficulty Level: At Grade Created by: CK-12
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Would you eat seaweed?

Seaweed is commonly eaten in many parts of the world. It's good for you, too; it's high in nutrients and low in calories. You have probably eaten processed seaweed and not even known it, since it's used as a thickener in foods like ice cream. Seaweed and other protists are also food for many, many animals in the ecosystem.

Importance of Protists

Humans could not live on Earth if it were not for protists. Why? Protists produce almost one-half of the oxygen on the planet through photosynthesis, decompose and recycle nutrients that humans need to live, and make up a huge part of the food chain.

Humans use protists for many other reasons:

  • Many protists are also commonly used in medical research. For example, medicines made from protists are used in treatment of high blood pressure, digestion problems, ulcers, and arthritis.
  • Other protists are used in scientific studies. For example, slime molds (including D. discoideum, a soil-living protist) are used to analyze the chemical signals in cells.
  • Protists are also valuable in industry. Look on the back of a milk carton. You will most likely see carrageenan, which is extracted from red algae. This is used to make puddings and ice cream solid (Figure below). Chemicals from other kinds of algae are used to produce many kinds of plastics.

Ice cream is an example of a food made with ingredients derived from algae.


  • carrageenan: Extract from red algae used as a food additive.


  • Protists make up a huge part of the food chain and supply much of the oxygen we breathe.
  • Protists are used in medicine and as food additives.


Use the resource below to answer the following questions.

  1. What would the potential benefit be to having algae ponds next to power plants?
  2. What are two basic ways to extract oil from algae?
  3. What does "carbon neutral power source" mean? How could such a power source benefit humankind?


  1. How are protists important to people?
  2. How are protists important to the ecosystem?

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Extract from red algae used as a food additive.

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Difficulty Level:
At Grade
7 , 8
Date Created:
Nov 29, 2012
Last Modified:
Aug 30, 2016
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