1. Classifying Organisms
7th Grade Science

2. You will be able to explain why classification systems are important.
Objectives:
You will be able to explain why classification systems are important.
You will be able to demonstrate your understanding with a dichotomous key.

3. Why do Scientists Classify?
Easier to study
Less confusion
Easier to see connections
How?
Physical characteristics
DNA

4. Types of Cells Prokaryotes No Nucleus Eukaryotes Very small
Bacteria
Domains: Bacteria and Archaea
Eukaryotes
Cells contain a nucleus
Larger than prokaryotes
Domain Eukarya

6. Scientific Naming Why? Binomial Nomenclature General Rules Canis lupis
Reduces confusion
Binomial Nomenclature
Two words for every name
Greek or Latin
Genus species (ex. Canis lupis)
General Rules
Always use italics or underline when written
Capitalize genus
Lowercase for species
Canis lupis

7. Taxonomy
Taxonomy:
Classification of organisms based on characteristics
8 levels
Each level has fewer organisms
Which organisms are more similar?
Same genus
Same family

8. 3.1 Classifying life
Taxonomy is the process of identifying and classifying living things.
A Swedish scientist and explorer named Carolus Linnaeus (1707–1778) developed a system of classification in the 1700s.
There are currently seven levels of classification.

9. 3.1 Levels of classification
For animals, the levels of classification are: kingdom, phylum, class, order, family, genus, and species.
At what level are these two animals classified differently?

10. Kingdoms of Life Separated by common characteristics 6 kingdoms
Archaebacteria
Eubacteria
Protista
Fungi
Plantae
Animalia

11. Topic: Classification Tools
What tools can scientist use to classify organisms?

12. Classification Tools
Suppose you to fishing and catch a fish you don’t recognize. How could you figure out what type of fish you have caught?

13. Dichotomous Key
Is a series of descriptions arranged in pairs that lead the user to identification.

14. Divides a larger group in smaller groups
Dichotomous Key
Divides a larger group in smaller groups
Typically, it may separate objects into groups that “have it” and those that “don’t have it”

15. Divides a larger group in smaller groups
Dichotomous Key
Divides a larger group in smaller groups
Typically, it may separate objects into groups that “have it” and those that “don’t have it”

16. 3.2 Dichotomous Keys
A dichotomous key turns questions into paired statements.

17. Classification Today
Scientists use shared characteristics to hypothesize how closely related living things are
The more shared characteristics organisms have, the more closely related they are
Cladograms: branching diagrams showing the similarities and differences between organisms

18. Look at these Pictures

19. 3.2 Dichotomous Keys
Most dichotomous keys are designed to identify small groups like trees, butterflies, and song birds.
Can you suggest a way to tell these arthropod classes apart?

20. What do they have in
Common?

21. Copy this diagram

22. Dichotomous Key of Transportation Vehicles
Vehicles with wheels:

23. Dichotomous Key of Transportation Vehicles
Vehicles with wheels:
Canoe, boat, sailboat,
Unicycle, skates, a/p, bike, train, car, bus

24. Dichotomous Key of Transportation Vehicles
Vehicles with wheels:
Unicycle, skates, ap, bike, train, car, bus
Canoe, boat, sailboat,
Wheels made of rubber/plastic:

25. Dichotomous Key of Transportation Vehicles
Vehicles with wheels:
Unicycle, skates, ap, bike, train, car, bus
Canoe, boat, sailboat,
Wheels made of rubber/plastic:
Unicycle, skates, ap bike, car, bus
train

26. Dichotomous Key of Transportation Vehicles
Vehicles with wheels:
Unicycle, skates, ap bike, train, car, bus
Canoe, boat, sailboat,
Wheels made of rubber/plastic:
Unicycle, skates, ap bike, car, bus
train
Carries over 10 people:

27. Dichotomous Key of Transportation Vehicles
Vehicles with wheels:
Unicycle, skates, bike, train, car, bus
Canoe, boat, sailboat,
Wheels made of rubber/plastic:
Unicycle, skates, bike, car, bus
train
Carries over 10 people:
Bus, ap
Unicycle, skates bike, car

28. What are These?

29. Animals

30. Dichotomous Key of Animals
Animals with 4 legs

31. Dichotomous Key of Animals
Animals with 4 legs:
Ostrich, worm, shark, man, rooster
Horse, gorilla, cow

32. Ostrich, worm, shark, man, rooster
Dichotomous Key of Animals
Animals with 4 legs :
Horse, gorilla, cow
Ostrich, worm, shark, man, rooster
Animals with tail:

33. Ostrich, worm, shark, man, rooster
Dichotomous Key of Animals
Animals with 4 legs:
Horse, gorilla, cow
Ostrich, worm, shark, man, rooster
Animals with tail:
Horse, cow
gorilla

34. Ostrich, worm, shark, man, rooster
Dichotomous Key of Animals
Animals with 4 legs:
Horse, gorilla, cow
Ostrich, worm, shark, man, rooster
Animals with a tail:
Horse, cow
gorilla
Animals with utters:

35. Dichotomous Key of Animals
Animals with 4 legs:
Horse, gorilla, cow
Ostrich, worm,
shark, man, rooster
Animals with a tail:
Horse, cow
gorilla
Animals with utters:
cow
horse

36. Tips for Classifying
Carefully observe objects to “notice” similarities and differences
Place objects into either one group or another – not both groups
Examine each group you create – to see if it can be further subdivided

37. Class Activity
Fish Classification

38. Levels of Classification
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
Mnemonic Device?

39. Domains
Major Groups
Three domains
Bacteria
Archaea
Eukarya

40. Review Naming: Binomial Nomenclature Levels of Classification
3 domains
Types of Cells
Kingdoms of Life