From two kingdoms to five
How new kingdoms were added.
Where does it go?
Amoeba moves like an animal, but it is a single cell. Plants and animals are many-celled.
In a system with only Plantae and Animalia, what is the problem with Amoeba?
What this lesson covers
The idea
The two-kingdom system (Plantae, Animalia) could not place unicellular organisms, so Protista was added; bacteria, lacking a true nucleus, became Monera; and fungi, non-moving heterotrophs that absorb nutrients, became a separate kingdom.
Where does it go?
Amoeba moves like an animal, but it is a single cell. Plants and animals are many-celled.
In a system with only Plantae and Animalia, what is the problem with Amoeba?
- It does not fit clearly in either kingdom
- It fits perfectly in Plantae
- It fits perfectly in Animalia
Adding kingdoms
Press Next step.
Each kingdom fixed a problem
Every new kingdom was added because some organisms did not fit the older ones. Protista took the unicellular microscopic organisms, Monera took the bacteria that lack a true nucleus, and Fungi took the non-moving organisms that absorb nutrients.
The two-kingdom system (Plantae, Animalia) could not place unicellular organisms, so Protista was added; bacteria, lacking a true nucleus, became Monera; and fungi, non-moving heterotrophs that absorb nutrients, became a separate kingdom.
Notes
The two kingdoms grew to five: Protista for unicellular organisms, Monera for bacteria without a true nucleus, and Fungi for non-moving heterotrophs that absorb nutrients.
Check yourself
Which two kingdoms were in the two-kingdom system?
Why was Protista added?
Why were bacteria placed in Monera?
Why did fungi get a separate kingdom?
- Monera and Fungi. These were added later, when the two kingdoms could not place all organisms.
- Plantae and Animalia — correct. Yes!
- Protista and Monera. These were added later to the two-kingdom system.
- Mushrooms did not move. Mushrooms led to the Fungi kingdom, not Protista.
- Bacteria have a true nucleus. Bacteria do not have a true nucleus. They were placed in Monera.
- Unicellular organisms did not fit in Plantae or Animalia — correct. Yes!
- They do not have a true nucleus, unlike an amoeba — correct. Yes!
- They are multicellular. Bacteria are unicellular, like an amoeba.
- They absorb nutrients like mushrooms. Absorbing nutrients is why fungi like mushrooms were given a separate kingdom, not why bacteria were.
- They are unicellular and have a true nucleus. That description fits Protista in the book.
- They do not move like plants, but they are heterotrophic and absorb nutrients — correct. Yes!
- They make their own food. Fungi are heterotrophic, so they do not make their own food.