Download Domains of Life - Spring Branch ISD

Domains of Life- KEY
All living organisms are classified into one of three domains. The three domains currently recognized
are
1. bacteria
2. archaea
3. eukaryota
Bacteria are unicellular, prokaryotic organisms. They are the most abundant organisms on earth with
an estimated 5 nonillion (5,000,000,000,000,000,000,000,000,000,000) individual organisms. Fun
Fact: There are more bacteria in one person's mouth than there are people in the world. Bacteria are
very small and come in a variety of cell shapes and sizes. Although some bacteria are harmful to
humans, many are useful or even necessary for life.
Archaea are unicellular, prokaryotic organisms. Archaea are similar in size and shape to bacteria, but
usually are not harmful to humans. Some archaea are even used to treat sewage. Many archaea live in
extreme environments. There are archaea that live in places that are hot enough to boil water, colder
than freezing, or 10 times saltier than the ocean. Despite what they look like, they are more closely
related to eukaryota than bacteria.
Eukaryota are eukaryotic organisms that can be either unicellular or multicellular. Eukaryota cells are
larger and more complex than both bacteria and archaea cells. Almost all large organisms, including
humans, belong in this domain. They are more closely related to archaea than bacteria.
Write the letter of each word or phrase below in the correct section of the Venn Diagram.
Word Bank:
A- Living organism
B- Cells are small
C- Cells are larger
D- Some live in extreme heat
E- Some live in extreme cold
F- Unicellular
G- Unicellular or multicellular
H- Prokaryotic
I- Eukaryotic
J- Many are harmful to humans
K- Humans are in this domain
L- Most abundant organisms
M- Related to each other