Introduction to Taxonomy - Online Tutor, Practice Problems & Exam Prep

Taxonomy classifies living organisms into eight categories: domain, kingdom, phylum, class, order, family, genus, and species. The three domains of life are Bacteria, Archaea, and Eukarya, with Bacteria and Archaea being prokaryotic (lacking a nucleus) and Eukarya consisting of eukaryotic cells (containing a nucleus). The Eukarya domain includes four kingdoms: Animalia, Plantae, Fungi, and Protista. Organisms can also be categorized by energy acquisition into producers (autotrophs), consumers (heterotrophs), and decomposers, highlighting the flow of energy from the sun through these groups.

Introduction to Taxonomy

In this video, we're going to begin our introduction to taxonomy. Now, taxonomy is really just defined as the branch of science that classifies, identifies, and names living organisms. And really what you guys need to know is that there are 8 categories that are used to classify all living organisms. And down below in this image, we're going to introduce these 8 categories from the most inclusive category of domains, which includes all living organisms, down to the least inclusive category, which would be the species, which only includes one type of living organism. And so, the more inclusive the category is, the more different types of living organisms it includes. And so from the most inclusive category of domain to the least inclusive category of species, the 8 categories are domain, kingdom, phylum, class, order, family, genus, and species. And so down below what we have is a little memory tool to help you guys remember these 8 categories in the correct order from most inclusive to least inclusive. And this little memory tool is just, dear King Philip came over for great soup. And so because the first letter of each of these categories is unique, we can use that to build a memory tool. And so if you remember that dear King Philip, right here, actually came over for great soup, then you'll be able to remember these 8 categories and put them in the correct order, from most inclusive to least inclusive. And so this year really concludes our introduction to taxonomy. And as we move forward, we'll be able to talk a little bit more about it. So I'll see you guys in our next video.

Which branch of biology is concerned with the naming and classifying of organisms?

• A. Bioinformatics.
• B. Taxonomy.
• C. Genomics.
• D. Evolution.
• E. Biology.

3 Domains of Life

So from our last lesson video, we know that there are 8 categories of life used to classify all living organisms. And the most inclusive of those eight categories is the domain. But really there are 3 domains of life, and that's the focus of this video. So once again, the broadest and the most inclusive categories of life are the 3 domains, which we have numbered down below. And so the first domain of life is domain bacteria. The second domain of life is domain archaea. The third and final domain of life is domain eukarya. Now, domain bacteria and domain archaea can be grouped together because they both consist of what are known as prokaryotic cells. Now later in our course, we'll talk more about these prokaryotic cells, but for now, what you guys should know is that these prokaryotic cells lack an organelle called the nucleus. Now the eukaryote domain, on the other hand, these consist of eukaryotic cells. And once again, we'll talk more about eukaryotic cells later in our course, but for now, you should know, that eukaryotic cells will actually contain a nucleus. So you could think of them pretty much as being the opposite of prokaryotic cells which lack the nucleus. Now if you take a look at our image down below, what you'll notice is we are showing you the 3 domains here, domain bacteria, domain archaea, and domain eukarya. And this portion right here of the image, scientists will refer to as a phylogenetic tree. But for our purposes here in this video, you can just think of it as the tree of life, and it's showing us where all organisms, all living organisms, where they fall and how they can be categorized. And so on this horizontal axis here, what we have is time. And so the further to the left you are on the axis, the further in the past you are. And as you make your way towards the right of the image, you make your way towards the present. And so in today's present time, there are these three domains, domain bacteria, archaea, and eukarya. However, if you go way back into the past, there is evidence that suggests that all life came from a common ancestor, and this is just a theory. So, it can never be proven true, but there is lots of support for this idea. And so what you'll notice is that the theory shows that life came from a single common ancestor but over time, as we make our way to the right, notice that through natural selection and evolution, these three different branches of life came to exist, the 3 different domains. Now once again, domain bacteria, and domain archaea can be grouped together, which is why we have these brackets around them, and they can be grouped together because they both consist of prokaryotic cells. So they can be called prokaryotes. And as we mentioned up above, prokaryotic cells lack an organelle called a nucleus. But also, prokaryotic cells are unicellular, meaning that they're only made up of just one single cell. Whereas down here, what you'll notice is with the domain eukarya, this is where humans fall, like ourselves. And, these are going to be consisted of eukaryotic cells, so they're referred to as eukaryotes as well. Now, eukaryotes, although you may think of humans as being multicellular, eukaryotes can either be unicellular or multicellular. And so it includes all multicellular organisms that you can think of, but it also includes some unicellular organisms as well. And so that's something important to keep in mind. But once again, later in our course, we'll talk even more about these prokaryotes and eukaryotes. For now, you should focus on the 3 domains of life, domain bacteria, domain archaea, and domain eukarya. And so this here concludes our introduction to the 3 domains of life. And as we move forward in our course, we'll be able to get a little bit of practice with this idea. So I'll see you guys in our next video.

Introduction to Taxonomy Example 1

Alright. So here we have an example problem that wants us to fill in the 2 blanks here in this sentence using one of these 4 potential answer options down below. And the example problem says, according to the diagram over here, A is blank whereas B is blank. And so when we take a look at this diagram over here notice that on one end what we have is A and on the opposite end of the diagram, what we have are the 3 domains of life, domain bacteria, archaea, and eukarya. And so, notice that A is right here at this position and B is specifically pointing to this position right here. And so when we take a look at option A here it says, that A is the most recent species to evolve on earth. But, of course, we know from our last lesson video that when we see a diagram like this one, that it's actually based on time and, furthest to the right, what we have is the present. So this represents the present. And as you go backward, we're actually going into the past. And so, the three domains of life are what we have in today's present world. However, going backward into the past, this is where we started. And so, what we're saying is that, A, by saying that it is the most recent species to evolve on earth. It's not really recent at all if it's way back in the past. A, is in the past and, the most recent species to evolve are going to be in the present, somewhere towards the right of the diagram. And so what that means is we can eliminate answer option A and answer option B since both of them say that for this first blank A is the most recent species to evolve on earth, and we know that's not right. Instead, we know that A is going to be the common ancestor of all life, so it's either going to be option C or option D. That's the correct answer for this problem. And since both C and D have the same thing for the first blank, we need to take a look at, what it says for option B. So, B is, this option here says, the common ancestor of bacteria and archaea. And, this option here says that B is the last common ancestor of archaea and Eukarya. And so when we take a look at B, again, it's pointing to this specific location right here. And so, this is referring to the closest relationship between archaea and eukarya. The closest relationship between archaea and bacteria would be up here. So if you were to trace this back, this is the closest place that they meet. And so, what that means is we can eliminate answer option C because it says that B is, the common ancestor of bacteria and archaea, but that's not true of B. That would actually be up here. And so that only leaves answer option D here as the correct answer. And so, B is going to be the last common ancestor of archaea and eukarya. That's where they connect most recently right here. And so D here is gonna be the correct answer for this example problem, and that concludes this example solve. See you guys in our next video.

Kingdoms of the Eukarya Domain

In this video, we're going to introduce the kingdoms of the Eukarya domain. Although each of the three domains has their own respective kingdoms, in this video once again, we're only going to focus on the kingdoms of the Eukarya domain. What we need to recall from our previous lesson videos is that organisms in each domain can be further subdivided into kingdoms. The domain Eukarya specifically has four kingdoms that you guys should be aware of. Notice down below in our image, we're showing you that domain Eukarya has four kingdoms with each of these four boxes that we see down below.

The first kingdom is Kingdom Animalia, which includes tigers, humans, all the insects, and other multicellular organisms consisting of multiple types of cells. The next kingdom is Kingdom Plantae, which includes flowers, plants, trees, and other multicellular entities. The third kingdom within the domain Eukarya is Kingdom Fungi, which of course includes fungi and mushrooms, and they are mostly multicellular. The fourth and final kingdom of Domain Eukarya is the Protista, or Protists. Protists can be unicellular, but they can also be multicellular, as shown in this image.

Eukaryotes, or organisms that fall in the eukaryote domain, because of the protists, can either be unicellular or multicellular. You guys should be aware of and familiar with these four different kingdoms of the Domain Eukarya. This here concludes our introduction to these kingdoms. As we move forward, we'll continue to talk more about how organisms can be classified. I'll see you in our next video.

Introduction to Taxonomy Example 2

So here we have an example problem that's asking which of the following kingdoms is not part of the eukaryotic domain. And we've got these 4 potential answer options down below. Now, of course, we know from our previous lesson video that kingdom Plantae certainly is one of the kingdoms of the eukarya domain. So because it is and we're looking for the one that is not, we can cross off option a. And the same goes for option b, kingdom Protista, we know for sure is going to be one of the kingdoms of the eukaryote domain from our last lesson video. So we can also cross off option b. And once again, option c, kingdom Fungi, we also know is one of the 4 kingdoms within the eukarya domain. So we can cross off option c. So then, of course, this leaves option d here, kingdom Eubacteria, bacteria in it, which we know is an entirely separate domain from the eukaryotic domain. And so, option d here is the only one that is not part of the eukaryotic domain. And so notice that there are 3 domains here that are listed that are part of the eukaryotic domain. And the 4th one that is not listed here is kingdom Animalia, which is the one that humans, you and I, fall into. But for now, option d here is the correct answer for this example problem, so I'll see you guys in our next video.

The proposal that one type of organism can change into another type over a long period of time is known as:

• A. Creativity.
• B. Evolution.
• C. Natural history.
• D. Preconception.
• E. Preservation.

Categorizing Life Based on Energy Acquisition

In this video, we're going to introduce yet another way that scientists can classify living organisms by talking about categorizing life based on energy acquisition. And so scientists can actually categorize living organisms into 3 classes just based on how they acquire their energy. And so notice down below we have a list of each of these three classes. And so the very first class are going to be the producers, which are also sometimes referred to as autotrophs. And so the producers or autotrophs, as their name implies with the producers here, are going to acquire their energy by making or producing their own food without having to eat any other living organisms. Now the second class that we have here are the consumers which are also sometimes referred to as the heterotrophs, And so the consumers or the heterotrophs, as their name implies with the consumer part, they're going to acquire their own energy by eating or consuming other living organisms. And then third, last but not least, what we have are the decomposers, and the decomposers, as their name implies, are going to acquire their energy by decomposing other things like wastes and dead organisms. And so when we take a look at our energy our image, I'm sorry, down below, we'll be able to see and visualize the difference between these producers, consumers, and decomposers. But first what you should note is that most of the energy that's utilized by life, is going to originate from our sun. And with every single energy transfer there is in this process, some energy is always going to be lost in the form of heat. And this is an idea that we'll get to talk more about later in our course once we start talking about the laws of thermodynamics. But for now, let's take a look at our image down below just to clear up some of the things that we've talked about. And so once again, most of the energy utilized by life is going to originate from our sun. And so notice here what we have is an image of our Sun where most of the energy originates. And notice that energy, the transfer of energy, is going to be symbolized with this orange arrow here. And so you can see that the energy from the sun, can be captured by these producers here. And so once again, the producers are sometimes referred to as autotrophs because they can make or create their own food essentially by themselves without relying on other living organisms. And so notice here we can put in the word producers, or we could have also filled in autotrophs. Both of them would apply here. Now, notice over here what we have are the consumers, like this bunny rabbit. The consumers are also sometimes referred to, as we've mentioned up above, heterotrophs, because they eat other living organisms to obtain their energy. And so, for example, this little bunny rabbit right here would eat the producer, eat the grass, in order to obtain its energy. And so there's a transfer of energy from the sun to the producers and then from the producers to the consumers that eat the producers. And then, eventually, as sad as it might sound, the bunny rabbit is ultimately going to pass away, and when it does, there are these other living organisms that we call decomposers, and these decomposers will eat the dead organisms and wastes. And so what we see is that the energy gets transferred from the consumers down to the decomposers. And so, ultimately, you can see the flow of energy from the sun to the producers, to the consumers, and to the decomposers. And the decomposers will also eat the dead producers as well, and so that's why you can see these, the orange energy here. But what you'll also notice is that in the green arrow here, we're representing matter, and matter is really just, anything that can take up space and has mass. And so, you can see that matter will also be flowing through this process. And so, ultimately, when these decomposers die, the nutrients can make its way into the soil and that nutrients in the soil can be used by the producers. And so there's a cycle of matter within this process here. And then once again, with every energy transfer, what you'll notice is that heat is being lost at each of these steps here. But this is a process that relates to thermodynamics, which we'll worry about later in our course. For now, what you guys should note is that most of the energy utilized by life comes from the sun, and you should be able to distinguish between producers, consumers, and decomposers. And so this here concludes our lesson on how we can categorize life based on energy acquisition and we'll be able to get some practice with this moving forward in our course. So I'll see you guys in our next video.

Introduction to Taxonomy Example 3

Alright. So here we have an example problem that wants us to complete the sentence here using one of these 4 potential answer options down below. And the example problem says autotrophs are also called either consumers, synthesizers, producers, or carnivores. Now of course, what we need to recall from our last lesson video is that autotrophs are going to be organisms that are going to create their own food. And so they're able to create their own food using nonliving things. And so, you can see this auto prefix here, is one that means self. And so, when it has autotroph, it's basically saying it can create their own food on their own by themselves, for instance. So another name for autotrophs, of course, we know from our previous lesson video, is going to be producers, and that's because producers produce or create their own food. So the correct answer is going to be option C for this example problem. Now recall that consumers are going to have to consume their food by eating other living organisms. Synthesizers is not really the term that we use to refer to these. And then carnivores are going to be organisms that eat meat. And so, we did also did not really talk about this in our previous lesson video, so we should have been able to eliminate that one. Once again, autotrophs are also called producers, and that concludes this example. So I'll see you all in our next video.

Biologists can divide living organisms into two groups:autotrophs and heterotrophs, which differ in _________.

• A. Their method of obtaining energy.
• B. The characteristics of life.
• C. Their mode of inheritance.
• D. The way that they generate ATP.

Here’s what students ask on this topic:

What are the eight categories used in taxonomy to classify living organisms?

The eight categories used in taxonomy to classify living organisms, from the most inclusive to the least inclusive, are: domain, kingdom, phylum, class, order, family, genus, and species. The domain is the broadest category and includes all living organisms, while the species is the most specific category, including only one type of organism. A helpful mnemonic to remember these categories in order is: 'Dear King Philip Came Over For Great Soup,' where each initial corresponds to a category.

What are the three domains of life and how do they differ?

The three domains of life are Bacteria, Archaea, and Eukarya. Bacteria and Archaea consist of prokaryotic cells, which lack a nucleus and are typically unicellular. Eukarya consists of eukaryotic cells, which contain a nucleus and can be either unicellular or multicellular. Bacteria and Archaea are often grouped together as prokaryotes, while Eukarya includes more complex organisms such as animals, plants, fungi, and protists.

What are the four kingdoms within the Eukarya domain?

The four kingdoms within the Eukarya domain are Animalia, Plantae, Fungi, and Protista. Kingdom Animalia includes multicellular organisms like humans and insects. Kingdom Plantae consists of multicellular plants such as flowers and trees. Kingdom Fungi includes mostly multicellular organisms like mushrooms. Kingdom Protista includes both unicellular and multicellular organisms, such as algae and protozoa.

How do scientists categorize living organisms based on energy acquisition?

Scientists categorize living organisms based on energy acquisition into three classes: producers (autotrophs), consumers (heterotrophs), and decomposers. Producers make their own food using sunlight (photosynthesis) or chemical energy (chemosynthesis). Consumers obtain energy by eating other organisms. Decomposers acquire energy by breaking down dead organisms and waste products, recycling nutrients back into the ecosystem.

What is the significance of the phylogenetic tree in taxonomy?

The phylogenetic tree, also known as the tree of life, is significant in taxonomy as it illustrates the evolutionary relationships among different organisms. It shows how all living organisms are connected through common ancestry and how they have diverged over time through natural selection and evolution. The tree helps scientists understand the genetic and evolutionary connections between species, aiding in the classification and study of biodiversity.