Living Things · Living things and their classification
The Kingdoms of Living Things
At a tianguis (open-air market) in Oaxaca you find an ahuehuete (Montezuma cypress), mushrooms growing on wood, a fly on a piece of fruit, and, in the yogurt you eat for breakfast, thousands of bacteria. All of them are living things, but they look nothing alike. To keep from getting lost in so much diversity, scientists sort them into big groups called kingdoms. What do they look at to do it?
Three questions, five kingdoms
If you compare a bacterium from yogurt with an ahuehuete, both are alive, but their size, their cells, the way they feed, and the way they reproduce are completely different. To group them, scientists ask three questions about their cells and their nutrition, and they also check how they reproduce.
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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.
Classify these organisms into their kingdom: a holm oak, an amoeba, a mushroom, an eagle, and yoghurt bacteria. Justify each choice using a characteristic of the…
Classify these organisms into their kingdom: a holm oak, an amoeba, a mushroom, an eagle, and yoghurt bacteria. Justify each choice using a characteristic of the corresponding kingdom.
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.
If you leave a tortilla or a slice of damp bread on a covered plate for a few days, you will see mold grow even though it has received no sunlight. How does that living thing get nutrients if it has no mouth and no green leaves?
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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.
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.
In a garden, a rosebush stays in the same place all the time, capturing light, while a hummingbird searches for nectar from flower to flower. What essential differences separate the life of a plant from that of an animal?
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Compare two organisms belonging to the kingdom Protoctista: the Paramecium* (unicellular, heterotrophic, and with cilia to move) and the giant Kelp* (multicellular, over…
Compare two organisms belonging to the kingdom Protoctista: the Paramecium (unicellular, heterotrophic, and with cilia to move) and the giant Kelp (multicellular, over 20 meters long, and photosynthetic autotroph).
a) Justify why including both in the same kingdom creates contradictions when compared with the criteria that define Plants and Animals.
b) Explain why, despite their similarities to them, the paramecium is not classified as an animal nor kelp as a true plant.
Every classification is a model: it helps to organize, but nature does not always fit into boxes. When an organism appears that mixes traits from several kingdoms, a hypothesis about its relationships is proposed and tested against more data.
The five-kingdom scheme is a school model that is useful for comparing cell organization, nutrition, reproduction, and number of cells. With molecular data, three domains are recognized today: Bacteria and Archaea (prokaryotes) and Eukarya (eukaryotes: animals, plants, fungi, and protists). Classifications change when there is new evidence.
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A single-celled organism with a nucleus is discovered in a pond. It has chlorophyll when light is available, but in the dark, it engulfs food particles. Discuss which…
A single-celled organism with a nucleus is discovered in a pond. It has chlorophyll when light is available, but in the dark, it engulfs food particles. Discuss which kingdom you would classify it into and what problem cases like this pose for kingdom classification.
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.
Back to the beginning: now you can classify everything from the tianguis: the yogurt bacterium in Monera (a prokaryote that divides in two), the fungus on the wood in Fungi (a eukaryote that absorbs its food and reproduces by spores), the ahuehuete in Plants (a multicellular autotroph), and the fly in Animals (a multicellular heterotroph that feeds by ingestion and reproduces by gametes).
Summary
Let's practice! 3 medium exercises in this section