Write each definition on your flashcards. Underline the vocabulary word.
1. A virus is a single-celled organism that relies on living cells to reproduce and can change upon
2. A bacteria is a one-celled organisms with no nucleus.
3. A microorganism is a living thing that can be seen only with a microscope. They can be harmful or
4. A multi-celled organism is an organism which has different cells with different jobs. These cells may or
may not have a nucleus, but generally have all or most of the 6 or 8 organelles considered normal for
animal or plant cells.
5. Tiny organisms, or living things, that can cause disease are called germs.
6. A fungus is a single-celled or multi-celled organism that because it cannot move around or make its own
food must feed on dead organisms. (multi-celled include mushrooms, single-celled include yeast and
7. A single-celled organism is a one-celled organism that can feed and rid itself of waste, regulate its own
water balance, and reproduce. .
8. Bad germs that cause disease, or damage something alive so that another microorganism can cause disease,
are said to be harmful.
9. Good germs that do something to help plants or animals stay alive are called beneficial.
10. Animal-like one-celled organisms which eat microscopic organisms like bacteria are called amoebas.
11. Plant-like one-celled organism which contain chloroplasts are called algae.
Study Helpers. Let’s see if you have been paying attention. Can you answer these correctly?
12. How can bacteria be helpful? a) they break down food in the digestive track b) grow on uncooked chicken
c) can cause disease d) cause milk to spoil.
13. How can algae be helpful? a) can cause red tide b) can be single-celled or multi-celled
c) produce oxygen d) float on the surface of water.
14. What makes viruses especially harmful? a) they are smaller than bacteria b) they are single-celled
c) they need a living cell to reproduce d) they change as they reproduce.
15. How can microorganisms be harmful? a) they help plants take up nutrients from the soil b) tiny fish eat them
in the ocean c) some of them cause diseases d)millions of them can live in a handful of soil
16. Name one place you can find bacteria
17. Name one virus that is known to make us sick.