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Why Do Biological Classification Keys Always Present Two Choices

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The Easy Guide To Making A Dichotomous Key With Editable Examples

Virus structure and Classification : DNA and RNA virus

In the field of biology, classification plays a major role. With new species being discovered every day, its important to have techniques in place to identify and classify them. One such tool is the dichotomous key. It helps identify organisms by directing the user to look at the known organisms.

In this simple guide, we will explain what is a dichotomous key and how to create one. Some examples are provided in the dichotomous key examples section you can use any template to start your project right away. Download them as PNGs, JPEGs, SVGs or PDFs for publishing, printing, and sharing.

What Does It All Mean

Although classification creates order within the biological world, it can still be very difficult to identify similar organisms from one another. Through the use of dichotomous keys, focused prompts enable you to distinguish one species from another based on their unique morphology and characteristics. This ability to differentiate species is especially handy when dealing with the vast number of prokaryotes and unicellular eukaryotes that exist on this planet!

What Is Biological Classification Explain Its Purpose

Biological classification is the process by which scientists group living organisms. Organisms are classified based on how similar they are. Historically similarity was determined by examining the physical characteristics of an organism but modern classification uses a variety of techniques including genetic analysis.

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Putting It All Together

Throughout this unit, you have looked at the various traits and features that differentiate one organism from another. Often, those differences can be very obvious, while other times they are almost imperceptible. Biologists can spend years studying these small differences, as each trait can lead to a better understanding of an organism.

Dichotomous keys use these differences to help identify organisms. If you love nature hikes, a dichotomous key of the plants and animals in that region is a great way to really understand the diversity that can be found. The keys also bring attention to the variations between similar organisms, again highlighting the diversity of life.

Ready To Design A Visually Engaging Dichotomous Key

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Now that youve the templates, tools and tips to create a dichotomous key, were hoping youre ready to design a helpful chart in no time.

Simply remember: think of your user all the time as you list characteristics, write your copy, pick a layout and design the key.

In all cases, the key has to be easy to navigate and use.

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Features Of Kingdom Plantae

The significant features of the kingdom Plantae are listed here.

  • They have a cell wall.
  • Autotrophic mode of nutrition is followed. The reserve food is starch.
  • A big central vacuole is present.
  • There arent any excretory organs, nervous system, sense organs and muscular system.
  • No locomotion is seen except in some lower algae.
  • Plantae absorbs inorganic nutrients from outside.
  • They experience unlimited growth but have well-defined growing points.
  • The response to external stimuli is slow.
  • Excretory organs, nervous system and sense organs are present.
  • Reserve food as glycogen.

Any More Tips On Making A Dichotomous Key

We hope that this guide will help you familiarize yourself with the dichotomous key method. Make use of the editable templates to get a headstart in class. Invite your friends/ students to edit them online, and make a fun group activity out of it.

Any more useful tips on creating a dichotomous key that our readers can rely on? Do share them in the comments section below.

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Create The Rest Of The Chart

If youre working from a template, youll see that your work is almost done at this point. The title, subheading/main box and the rest of the shapes alongside the copy are done.

Want to change the flowing lines direction? Select and drag the line to wherever you want it to point. Thats it. Easy-peasy.

In the case of a canvas design, select Basics from the extreme left then Diagrams on the left.

This will show you different flowchart patterns. Pick the one you need to build the rest of your key.

The best part? Youve the flexibility to move the boxes in the pattern you pick simply by dragging them.

What Is It Important To Classify Living Organisms

BIODIVERSITY & calculating INDEX of DIVERSITY. Human impact and definitions for A-Level Biology

It is necessary to classify organisms because: Classification allows us to understand diversity better. Classification helps us to learn about different kinds of plants and animals their features similarities and differences. It enables us to understand how complex organisms evolve from simpler organisms.

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Tech Product Launch Dichotomous Key Template

This template pairs catchy colors and a simple layout for an effective dichotomous key design.

You can always tweak the colors or shapes if you like. Use it when sketching a concept that has first few obvious steps followed by branched out steps under yes and no options that both come to the same conclusion.

Why Do Biological Classification Keys Always Present Only Two Choice At Each Step

BTW I am doing a shark dichotomous key analysisNone


The biological classification keys always present only two choices at each step because it is simple, more efficient way of separating organism, without confusion. Biological classification is the process in which scientists group living organisms based on their similarities and differences. Originally similarity was determined by examining the physical characteristics of an organism but modern classification uses a variety of techniques including genetic analysis.

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How Hard Can It Be

Since dichotomous keys are just a series of choices, it’s understandable if you think they’re easy to create. And, that’s certainly correct for organisms with such obvious differences like the fish in the Minds On section. However, many organisms are very similar to one another, and only very small differences in appearance and in characteristics are apparent. You can imagine how difficult it would be to create a key that identifies all of the bacteria species! It is believed that there can be as many as 10,000 species of bacteria in one gram of soil. That would take one big key!

To create a useful dichotomous key, you have to be sure that each choice in a prompt is clear. If you have a question where both choices are possible, the key may fall apart from that point on. It is the creation of these clear and concise questions that creates the most difficulty. To give you a taste of this process, you will create a short dichotomous key based on some simple objects. Before you start, watch this video to get some pointers on how to create a dichotomous key.

Now that you understand the process, it is time to become a key creator!

What Is A Dichotomous Key

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Students and professionals use the dichotomous key to identify and classify objects into specific categories based on their characteristics. Its the most commonly used form of classification or type of identification key used in biology as it simplifies identifying unknown organisms.

Simply put, it is a method used to identify a species by answering a series of questions based on contrasting features that have two possible outcomes.

Dichotomous means divided into two parts, hence the dichotomous keys always present two choices based on the key characteristics of the organism in each step. By correctly selecting the right choice at each stage, the user will be able to identify the name of the organism at the end. The further you divide the key, the more you learn about the specimen you are trying to identify.

When creating a dichotomous key, both qualitative and quantitative factors are considered.

It can be done in both a graphical or written format . Most often, they are used to identify plant and animal species, although it can be used to classify any object that can be identified by a set of observable characteristics.

To easily draw connections between species to better establish proposed phylogeny create Cladograms.

What is the dichotomous key used for

A dichotomous key is usually used for

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Adansonian Or Numerical Classification

In most systems of bacterial classification, the major groups are distinguished by fundamental characters such as cell shape, Gram-stain reaction and spore formation genera and species are usually distinguished by properties such as fermentation reactions, nutritional requirements and pathogenicity. The relative importance of different characters in defining major and minor groupings is often purely arbitrary. The uncertainties of arbitrary choices are avoided in the Adansonian system of taxonomy. This system determines the degrees of relationship between strains by a statistical coefficient that takes account of the widest range of characters, all of which are considered of equal weight. It is clear, of course, that some characters, for instance cell shape or Gram-stain reaction, represent a much wider and permanent genetic commitment than other characters which, being dependent on only one or a few genes, may be unstable. For this reason, the Adansonian method is most useful for the classification of strains within a larger grouping that shares major characters.

Hierarchical taxonomic tree prepared from similarity matrix data. The dashed lines X and Y indicate levels of similarity at which separation into genera and species might be possible.

Select Your Visual Assets

Before you design any further, its best you decide what design assets to add to your dichotomous key.

Ask yourself: Do you want to add different shaped question/statement boxes in your key? The rectangles and circles used in this dichotomous key design show this in action:

Or, do you want to use different colors for the statement/question boxes but stick with the same shape:

Theres also a third option here: keeping all boxes shape and color the same but altering the color of the “yes” and “no” option boxes.

Its also best to settle on whether you want to add any engaging diagrams to your chart. The desktop illustration in this template, for instance, breathes life into the design.

One final design asset to think about: plain background or an overlaid one as in this example dichotomous key:

Again, choose what’ll best appeal to your users not yourself.

Working from the canvas or want to tweak shapes in a template? Pull out the gold from the left of the dashboard by selecting Graphics then Lines & Shapes.

This works for both the canvas and templates.

Want to tweak not change the boxs shape in the template? Select the box, click Edit and make changes from the menu bar that appears. Here you can change the shapes roundness, color and much more.

Go on to make the changes in the rest of the boxes in the template.

Change the copy too so that youre almost done with creating your dichotomous key.

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Software Technical Documentation Dichotomous Key Template

This ones a short and sweet dichotomous key template for easier concepts.

The best part? Not only are there arrows guiding the “yes” and “no” options, but there are arrows interconnecting various steps in the process too.

Use the template for visualizing steps in a process so users know what comes next no matter where they are in their process journey.

Organize Characteristics In Order

Basic Biology. Lesson 1: The Life Processes (GCSE Science)

In this step, start organizing the choices in a logical sequence on paper.

Heads-up: This might take 2-3 drafts as you figure out the best questions to ask first.

Want to ensure your dichotomous key makes it easy to reach the final conclusion? Start with asking questions on broad differences. Then narrow down specific choices/characteristics of the object to identify.

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What Do Plants And Animals Have In Common

Complete answer: Animals and plants have various things in common as both are living things and at some point in life both Will die. Plants and animals are made up of cells containing DNA and both of them require energy to reproduce and grow. The presence of DNA and RNA is the characteristic of both plants and animals.

Examples Of Dichotomous Key

D. Computer Program


3. Which of the following is NOT a reason to use the scientific name of an organism, instead of the common name?A. The scientific name contains useful information, such as the genus name, which tells what other species this organism is related to.B. The scientific name is unique to each biological species, while the same common name may be applied to several different species.C. The scientific name is easier to remember and is commonly used in conversation.D. None of the above.


Cite This Article

Biology Dictionary

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Consultation Services Lead Generation Dichotomous Key Template

Like the template above, this one is also for those who want to visualize and guide through a process with simple first few steps.

However, this template is the right pick for you when youve not two branched out options, but three.

The third branch has a few more options that are connected two the second branch keep, remove or add to these options and branches as needed.

Dichotomous Key Creation 101

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Choose five or six similar objects from around your home – or images of objects from the Internet that are related in some way .

Compile the images of your chosen items onto one page, and number them. Now, most objects you have will probably be easily identified, so assign a unique name to each item and keep that list to yourself. For example, if I had five drinking glasses, I could call the first glass George, the second one Fatima, the third, Maisy, etc. Using these names will prevent someone from simply going straight to the answers on the key and will encourage them to go through each question in your key carefully.

Create a dichotomous key that can be used to identify your chosen objects. Anyone who uses your key should be able to come up with a list that pairs the number assigned to each item with its name. For example, the user of your key may come up with the answer:

1 = George

As you can see, classifying organisms can be quite tedious. Taxonomists have to be highly trained to notice very small differences in structures and characteristics in order to be able to successfully identify organisms. The difficulty level is further magnified if the identification takes place out in a field or waist-deep in a stream. To make a successful key, you need to understand the differences between different groups of organisms.

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What Is A Dichotomous Key Used For

Its commonly assumed that dichotomous keys are most used in biology for helping with the classification and identification of organisms including animals, plants, and bacteria.

Thanks to the role that this graphic organizer plays though, its use isnt limited to biology. In fact, its used in various subjects and for different purposes.

Broadly, a dichotomous key helps:

  • Identify objects, plants and animals
  • Understand complex concepts easily
  • Organize raw data into an easy to use chart

This means the key is useful not only for helping identify things but also for assisting in decision-making.

Look at this example dichotomous key. Instead of identification, it helps social media managers take decisions:

All in all, a dichotomous keys use depends on its purpose and audience.

A biology teacher might use the chart to teach the classification of mammals to her students. On the flip side, a quality control manager can use it to ensure her team ships only high-quality pieces to customers by helping them make on-the-spot decisions with the key.

B Three Kingdom Classification System

In the year 1866, Ernst Haeckel, classified living organisms into three kingdoms i.e. Plantae, Protista, and Animalia. The new kingdom Protista included all those organisms, which lack the capability of tissue differentiation. This group included algae, fungi, and Protozoa. Later, kingdom Protista was reserved only for the unicellular organism.

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Need For Classification Of Living Organisms

  • The study of one or two organisms is not sufficient to know the essential features of the group.
  • All kinds of organisms do not occur in one locality.
  • Classification helps in knowing the relationship between the different groups of organisms.
  • It helps in knowing the evolutionary relationship between organisms.

You can download Biological Classification Cheat Sheet by clicking on the download button below

What Is The Best Way To Develop A Dichotomous Key

Inheritance part(2), Genotype vs phenotype, pedigree, monohybrid cross, Codominance. IGCSE biology

Below we have listed the steps you need to follow when creating a dichotomous key.

  • Step 1: List down the characteristics.
  • Step 2: Organize the characteristics in order.
  • Step 3: Divide the specimens.
  • Step 4: Divide the specimen even further.
  • Step 5: Draw a dichotomous key diagram.
  • Step 6: Test it out.
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    C Four Kingdom Classification System

    In addition to Protista, Plantae and Animalia, the four kingdom classification system included Monera. The studies with electron microscope made it clear that bacteria and related organisms have a different nuclear structure as compared to others. These are the prokaryotes. As a result of this, Copeland in the year 1956, introduced the kingdom-Monera. Fungi continued to remain with Plantae in this system.

    Taxonomic Keys: Meaning Suggestions And Types

    The below mentioned article provides an overview on Taxonomic Keys.

    Meaning of Taxonomic Key:

    A key is a device, which when properly constructed and used, enables a user to identify an organism. Keys are devices consisting of a series of contrasting or contradictory statements or propositions requiring the identifier to make comparisons and decisions based on statements in the key as related to the material to be identified.

    Thus, a taxonomic key is a device for quickly and easily identifying to which species an unknown plant belongs.


    The key consists of a series of choices, based on observed features of the plant specimen. It provides a choice between two contradictory statements resulting in the acceptance of one and the rejection of the other.

    A single pair of contradictory statements is called a couplet and each statement of a couplet is termed a lead. By making the correct choice at each level of the key, one can eventually arrive at the name of the unknown plant.

    Suggestions for the Use of Taxonomic Keys:

    Appropriate keys should be selected for the materials to be identified. The keys may be in a flora, manual, guide handbook, monograph, or revision. If the locality of an unknown plant is known, a flora, guide, or manual treating the plants of that geographic area may be selected.


    The introductory comments on format details, abbreviations, etc. should be read before using the key.

    Suggestion for Construction of Taxonomic Keys:

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