The kingdoms of living things
An oak tree, a mushroom, the bacteria in yogurt, and a seagull on the Malecón are all living things, but they look nothing alike. To keep from getting lost in so much diversity, scientists sort them into large groups called kingdoms. What do they look at to decide which kingdom each one belongs to?
Three questions, five kingdoms
Compare the bacteria in yogurt with an oak tree. Both are alive, but their size, their cells, and the way they feed are very different. Those differences are exactly the clues used to classify them.
With these three questions we can build the tree of the five kingdoms. Read it from top to bottom, like a decision key.
Look at the tree: if a branch says "multicellular, with a nucleus, that ingests food," that is the Animal kingdom. If it makes its food using light, it is Plants. And if it absorbs its food, whether it has one cell or many, it is a fungus.
| Kingdom | Cell type | Cells | Nutrition | Dominican example |
|---|---|---|---|---|
| Monera | prokaryotic | unicellular | autotrophic or heterotrophic | yogurt bacteria |
| Protista | eukaryotic | almost always unicellular | autotrophic or heterotrophic | amoeba, paramecium |
| Fungi | eukaryotic | uni- or multicellular | heterotrophic by absorption | bread mold, yeast |
| Plants | eukaryotic | multicellular | autotrophic (photosynthesis) | mangrove, royal palm |
| Animals | eukaryotic | multicellular | heterotrophic by ingestion | manatee, palm chat |
Name the six kingdoms of living things and give an example of an organism for each of them.
Name the six kingdoms of living things and give an example of an organism for each of them.
The diagram shows the classification tree of living things according to the five-kingdom model, but one kingdom is missing, marked with "?". Identify which kingdom it is…
The diagram shows the classification tree of living things according to the five-kingdom model, but one kingdom is missing, marked with "?". Identify which kingdom it is and explain the characteristics (cell type, number of cells, and mode of nutrition) that define it.
Create a table showing the five kingdoms of the traditional classification (Whittaker-Margulis), specifying for each: cell type (prokaryotic or eukaryotic), whether its…
Create a table showing the five kingdoms of the traditional classification (Whittaker-Margulis), specifying for each: cell type (prokaryotic or eukaryotic), whether its organisms are unicellular or multicellular, and its type of nutrition.
Kingdom Monera and kingdom Protista: the smallest ones
Which kingdom groups bacteria together? State which type of cell they have and give two examples of bacteria present in your daily life.
Which kingdom groups bacteria together? State which type of cell they have and give two examples of bacteria present in your daily life.
A microscopic organism is unicellular, has eukaryotic cells, and moves actively in search of food. Which kingdom does it belong to? Explain why it cannot be either an…
A microscopic organism is unicellular, has eukaryotic cells, and moves actively in search of food. Which kingdom does it belong to? Explain why it cannot be either an animal or a bacterium.
The amoeba and the paramecium move around and capture their food, as an animal would. Reason why they do not belong to the Animal kingdom and place them in the correct…
The amoeba and the paramecium move around and capture their food, as an animal would. Reason why they do not belong to the Animal kingdom and place them in the correct kingdom.
The Fungi kingdom
Leave a slice of damp bread on a covered plate for a few days and you will see a green and white fuzz grow, without any sunlight. How does that living thing feed itself if it has no mouth and no green leaves?
In your daily life there are fungi everywhere. Yeast makes bread and cake rise. Button mushrooms are eaten in salads. Mold spoils bread and forgotten fruit. Athlete's foot is a fungus that lives on the skin.
The Fungi kingdom is closer to your life than you think. Name three fungi (or products made thanks to fungi) from your daily life and explain the role of each one.
The Fungi kingdom is closer to your life than you think. Name three fungi (or products made thanks to fungi) from your daily life and explain the role of each one.
For centuries, mushrooms were considered plants. Explain at least two reasons why fungi are today classified in their own kingdom, separate from the plant kingdom.
For centuries, mushrooms were considered plants. Explain at least two reasons why fungi are today classified in their own kingdom, separate from the plant kingdom.
The yeast that makes bread rise is a unicellular fungus. Explain why it is not a bacterium, even though both are microscopic and single-celled, looking at the cell type…
The yeast that makes bread rise is a unicellular fungus. Explain why it is not a bacterium, even though both are microscopic and single-celled, looking at the cell type of each one.
The Plant kingdom and the Animal kingdom
In a yard, a rosebush stays in the same spot all the time, capturing light, while a palm chat searches for insects among the leaves. What essential differences separate the life of a plant from that of an animal?
One Dominican example of each multicellular kingdom: the mangrove (plant) protects the coast and the manatee (animal) lives in Caribbean waters. Both are eukaryotic and multicellular, but one makes its food and the other ingests it.
Which kingdom brings together multicellular living things that make their own food thanks to light? Name the cell organelle that makes this possible and give two…
Which kingdom brings together multicellular living things that make their own food thanks to light? Name the cell organelle that makes this possible and give two examples of organisms from that kingdom.
Summarise four characteristics of the Animal kingdom: cell type, number of cells, how they obtain food, and what they usually do to get it.
Summarise four characteristics of the Animal kingdom: cell type, number of cells, how they obtain food, and what they usually do to get it.
Algae carry out photosynthesis like plants, but in the five-kingdom model they are classified in the kingdom Protista. Explain how their organisation differs from that…
Algae carry out photosynthesis like plants, but in the five-kingdom model they are classified in the kingdom Protista. Explain how their organisation differs from that of plants (they do not form true tissues or organs such as roots, stems, and leaves: they have a thallus) and reason why the criterion "carries out photosynthesis" is not enough to classify a living thing.
Five kingdoms and three domains
The five-kingdom scheme is a very useful school model. But scientific classification is revised as new data come in, especially molecular data. Today living things are also grouped into three domains: Bacteria, Archaea, and Eukarya.
The bacteria of the school kingdoms are in the domain Bacteria. The other four kingdoms (Protista, Fungi, Plants, and Animals) are within the domain Eukarya. Archaea often live in extreme environments, such as very hot or very salty waters.
To order organisms from the simplest to the most complex, use cell type and number of cells: first the bacterium (prokaryotic, unicellular), then the amoeba, and then the multicellular eukaryotes.
Cyanobacteria, formerly called "blue-green algae", carry out photosynthesis. Explain why they stopped being considered algae and are classified in the kingdom Monera,…
Cyanobacteria, formerly called "blue-green algae", carry out photosynthesis. Explain why they stopped being considered algae and are classified in the kingdom Monera, stating which characteristic carries more weight than the way of feeding when classifying them.
Order these organisms from the simplest to the most complex and explain the criterion you have used: a fungus, a bacterium, an oak tree, an amoeba, and a seagull.
Order these organisms from the simplest to the most complex and explain the criterion you have used: a fungus, a bacterium, an oak tree, an amoeba, and a seagull.
Tricky cases and living things that depend on others
Nature does not always fit into a box. Some organisms mix traits, and others depend on other living things to survive.
If you separated the two partners on a bare, sunny rock, the fungus would have nowhere to get food, because it is a heterotroph. The alga could survive for a while with light, but it would dry out without the fungus's protection.
Some unicellular organisms, such as certain protists with chlorophyll, carry out photosynthesis in the light and eat particles in the dark. They do not fit well into "autotroph" or "heterotroph." This shows that the kingdoms are a model for organizing things, not a perfect box.
A student observes a lichen on a bare limestone rock and states: “It is a simple plant, because it is green and performs photosynthesis.” Refute their statement by…
A student observes a lichen on a bare limestone rock and states: “It is a simple plant, because it is green and performs photosynthesis.” Refute their statement by explaining the true biological composition of a lichen and which kingdoms its components belong to. Then, predict what would happen to each of these two organisms if you separated them and left them isolated on that same sunny rock with no soil, justifying your answer based on the type of nutrition of each one.
A space probe takes a dust sample on Mars containing microscopic particles made up only of a protein coat and an RNA molecule inside. In the laboratory, they show…
A space probe takes a dust sample on Mars containing microscopic particles made up only of a protein coat and an RNA molecule inside. In the laboratory, they show neither energy expenditure nor growth, but when placed in contact with a culture of living bacteria, they enter them and multiply rapidly, destroying the host cells. A newspaper headline announces: “First alien bacteria discovered!”. Refute this headline by explaining why this agent cannot be a bacterium nor be classified into any of the five kingdoms of living things.
An experimental forest plot is periodically sprayed with a product that eliminates all decomposing fungi without harming other living beings. After one year, it is…
An experimental forest plot is periodically sprayed with a product that eliminates all decomposing fungi without harming other living beings. After one year, it is observed that fallen logs and leaf litter accumulate intact, but the forest trees begin to wither from malnutrition. Justify the relationship between the accumulation of dead wood and the malnutrition of living trees, and predict what would happen to life on the planet if all decomposers disappeared.
Back to the beginning: you can now classify the living things from the start. The yogurt bacteria are in Monera (prokaryotic, unicellular). The mushroom is in Fungi (eukaryotic, absorbs its food). The oak is in Plants (multicellular, autotrophic). The seagull is in Animals (multicellular, ingests its food).