Classification schemes reflect orderly patterns and observable distinctions among objects and organisms. One of the most important classification schemes we use is the classification of life which includes two domains and six kingdoms.
One important thinking process of scientists is the ability to categorize. This is actually a process that all people use everyday! It turns out our brains are designed to sort things in order to help us keep track of details. While in daily life, you might categorize things based on your preferences, in science we categorize things based on their external structures (what they look like).
One of the first sets of groups we make in science, is the difference between living, non-living, and once-living things.
Living things have to have all five of the characteristics of life: made of cells, gets and uses energy, grows and develops, reproduces, and responds to their environment.
Once living things used to have all five of those characteristics, but now they don't. Examples of once-living things include cotton shirts, an apple (off its tree), dead things, etc.
Non-living things NEVER had all five of the characteristics (even if they have one or two of them). Examples of non-living things include metal, clouds, fire, etc.
Obviously observation is important when categorizing things because that's how you get details about the objects/living things you're classifying.
There are many ways to classify things and there are lots of correct ways to do it. In order for a categorization or classification to be correct, it just has to make total sense (all explanations are true).
We can use a tool called a classification key to figure out what unknown objects are. In order to use it, all you have to do is read the questions, answer yes or no, and then follow the directions.
When you make a classification system, you split everything into two groups. Make sure you have a reason for your grouping. Then you split those two groups into two groups each. And you keep splitting things into two groups until you only have one object in each group. Then you simply fill in the format of a key or a tree.
For a key, you write a question that will help your reader split the objects into two groups. Then you write instructions for your reader to continue to the next question or you inform them what the object is. For example, here is a small simple key below:
1. Is the coin silver?
a - Yes: penny
b - No: go to 2
2. Does the coin have ridges on the edges?
a - Yes: go to 3
b - No: nickle
3. Is the coin about an inch in diameter?
a - Yes: quarter
b - No: dime
For a tree, you simply draw lines separating the items into two groups, write your reasoning on the lines, and when you only have one object at the end of a line, you write its name and box it.
Classification systems are important because they help us keep track of the things we find, they help us describe the patterns we see in nature, and they help us see relationships between groups.
In the past, people thought that things were only either a plant or an animal. But throughout science's history, we keep finding organisms that are not plants and are not animals. For example, amoebas, yeast, mushrooms, and bacteria all are very different from both plants and animals.
Today, we have 5 main kingdoms. Plantae, Animalia, Fungi, Protista, and Monera.
PLANTAE:
All things in plantae have a cell wall made of cellulose, have chloroplasts that make their food, and have a nucleus.
ANIMALIA:
All things in animalia have no cell walls, eat their food, and have a nucleus.
FUNGI:
All things in fungi have a cell wall made of chitin, absorb their food, and have a nucleus
PROTISTA:
Protista is considered the garbage kingdom because it contains all the organisms that didn't fit easily into the other groups. The only things they have in common is that they all have a nucleus and they all like to live in damp or very wet places.
MONERA:
There are actually two kingdoms in monera, Archaebacteria and Eubacteria. Both of these groups contain the bacteria and nothing in monera has a nucleus. That's right. THERE ARE NO NUCLEI IN MONERA.
Overtime, when we gain new technology we learn new things about organisms. And in science, when we gain new information we fix our classification systems. Some examples of changes in the past include when we got rid of the pisces group (of fish) because their DNA showed they weren't really closely related to each other, when we studied the bacteria and split monera into the two groups, and when we moved dinosaurs on our classification tree to be closer related to birds than reptiles.
Categorizing:
splitting things into groups based on shared characteristics
Structure:
shape and details about what you see about object
Classification:
creating and explaining the groups that things belong in
Observation:
looking closely and noting details
Living:
things that have to have all five of the characteristics of life
Once-Living:
things that used to have all five of those characteristics but now don't
Non-Living:
things that NEVER had all five of the characteristics
Classification Key:
a tool used to help identify unknown objects and describe patterns we see in nature
Classification Tree:
a tool used to show relationships between objects
Plants:
organisms that have a cell wall made of cellulose, have chloroplasts that make their food, and have a nucleus
Animals:
organisms that have no cell walls, eat their food, and have a nucleus
Fungi:
atoms spread away from each other
Protists:
organisms that have a nucleus and like to live in damp or very wet places - garbage kingdom because the organisms in this group are VERY diverse
Monera:
organisms with NO NUCLEUS
Kingdom :
the five main groups of living things