1. Classifying and Exploring Life
Life Science
7th grade

2. Ch1 L.1 Characteristics of life
What characteristics to all living things have?

3. Ch1 L.1 Bellwork
Organism: things that have all the characteristics of life
Cell: smallest unit of life
Unicellular: things that are only made up of one cell
Multicellular: living things that are made up of two or more cells
Homeostasis: an organism’s ability to maintain steady internal conditions when outside conditions change

4. What makes something alive?
Together with your partner, come up with a list of things that make something alive.
Think of differences between a nonliving thing and a living thing.
What is an example of a living thing?
What is an example of a nonliving thing?
How do they differ?

5. Characteristics of life
Grow and develop
Reproduce
Are organized
Respond
Maintain internal conditions
Use energy

6. Organism
Must have ALL of the characteristics of life to be considered an organism
Use the characteristics of life as a checklist to see if something is an organism

7. Organization
Is an organism made of one cell (unicellular) or multiple cells (multicellular)?
Are the cells organized in a specific way?
In a multicellular organism, groups of cells usually have specific functions (your eye cells work differently than your heart cells)
Within the cell is there any organization?
Structures within the cell have different functions.

8. Growth and Development
Growth= increase in size
Unicellular organism: cell increases in size
Multicellular organism: grow as the number of cells increases
Development= changes that occur in an organism in its lifetime
Cells become specialized (skin cells vs muscle cells)
Dramatic changes= tadpole to frog or caterpillar to butterfly

9. Reproduction
The process by which one organism makes one or more new organisms
Necessary in order for living organisms to continue to exist
NOT ALL ORGANISMS REPRODUCE THE SAME WAY
Some just divide to become two where there was one
Some can reproduce without a mate (asexual reproduction)
Some require a mate (sexual reproduction)
Not all organisms have the same number of offspring

10. Let’s think about it
Why do reptiles/amphibians lay many eggs but humans generally only have one or two offspring?

11. Responses to Stimuli Organisms respond to changes in the environment
Internal stimuli
Stimulus: hunger; Reaction: look for food
Stimulus: thirst; Reaction: look for water
External stimuli
Examples: light, temperature, chemicals
Plants grow towards light
Animals respond to temperature changes by changing blood flow near skin

12. Homeostasis Cells need certain conditions to function properly
What is regulated?
Temperature: Body temperature is 37C or 98F
Shift= sweat or shiver to get back to normal
Water
Too much: go to the bathroom a lot
Too little: retain water
Your body can only regulate a certain amount

13. Ch1 L.1 Mini Lab p.12 Each person wears goggles
With your partner, sit facing each other
GENTLY toss foam ball at your partner’s face five times
You will warn your partner before each toss
Repeat but this time without warning your partner.
Switch seats now and repeat the process
Answer the following questions:
What were your responses when you were warned?
What were your responses when you were not warned?
Were your reactions reflex or responses?

14. Use Energy Everything you do requires energy Where does it come from?
Sun
Food

15. Ch1 L.1 Homework
p.16 #1-11
Outline Ch1 L.1
Study for quiz Ch1 L.1

16. Ch1 L.2 Classifying Organisms
What methods are used to classify living things into groups?
Why does every species have a scientific name?

17. Ch1 L.2 Bellwork
Binomial nomenclature: gives each organism a two-word scientific name (Homo sapien= human)
Species: is a group of organisms that have similar traits and are able to produce fertile offspring
Genus: a group of similar species
Dichotomous key: a series of descriptions arranged in pairs that lead the user to the identification of an unknown organism
Cladogram: a branched diagram that shows the relationships among organisms, including common ancestors

18. Ch1 L.2 Launch Lab p.18 Look at the groups of items in front of you
Together with your partner, organize the items into two groups
Document what you used to organize the items
Start over and use a different characteristic to re-organize your items into two groups
Let’s discuss:
What did you use to separate the items?
Why do you think it’s important for scientists to have rules for organizing items?

19. Classifying Living Things
How are things organized?
How is your house organized?
How is a grocery store organized?
Aristotle was a Greek philosopher who first classified things: into plants and animals

20. Determining Kingdoms
Carolus Linnaeus (1700s): classified organisms based on similar structures
Two main groups: Animale vs Vegetabile kingdom
This has since been improved into five kingdoms by Robert H Whittaker
Monera, Protista, Plantae, Fungi and Animalia

21. Kingdoms

22. Determining Domains Classification method is called systematics
Uses information about the organism to classify them
Cell type, habitat, food and energy sources, features and ancestors
Three domains to classify BEFORE kingdoms
Bacteria, Archaea or Eukarya

24. Scientific Names Use binomial nomenclature to name organisms
Two-word scientific name
Genus + Species
Genus: group of similar species
Species: group of organisms with similar traits that can produce fertile offspring
What do you notice about the taxonomic groups as you go down the table?
How do species and genus relate to kingdoms and domains

25. Scientific names cont’d
A common name can refer to many different organisms but there is only one scientific name for each type of organism
You may call two trees pine trees but they could be different types of pine trees
Each one has its own scientific name
Scientific names are accepted worldwide
Why is it important to have scientific names?

26. Classification tools
Dichotomous keys: series of descriptions arranged in pairs that allows identification of an organism
Answering one description brings you to another pair of description or to the identity of the organism
Kind of like a game of guess who

27. Dichotomous key 1. 2. 4. 5. 3. 6.

28. Classification tools cont’d
Cladograms: branched diagram that shows relationships among organisms, including ancestors.
Each branch follows a new characteristic
Each characteristic is present in all organisms to the right of it
amniotic egg The type of egg produced by reptiles, birds, and prototherian (egg-laying) mammals (amniotes), in which the embryo develops inside an amnion. The shell of the egg is either calcium-based or leathery.

29. Ch1 L.2 Mini Lab p.23
*Remember: a genus name describes a common characteristic that all members of a group share

30. Ch1 L.2 Homework
p.24 #1-9
Outline Ch1 L.2
Study for quiz Ch1 L.2

31. Ch1 L.3 Exploring Life
How did microscopes change our ideas about living things?
WHat are the types of microscopes, and how do they compare?

32. Ch1 L.3 Bellwork
Light microscope: use light and lenses to enlarge an image of an object
Compound microscope: a light microscope that has more than one lens to magnify an object
Electron microscope: use a magnetic field to focus a beam of electrons through an object or onto an object’s surface

33. The Development of Microscopes
Robert Hooke: (mid 1600’s) discovered and named cells
Anton Van Leeuwenhoek: (late 1600’s) improved on microscope and magnified image 270x

34. Types of Microscopes
All microscopes magnify objects (make them appear larger than they are)
Resolution- how clearly the magnified objects can be seen. **This changes depending on the type of microscope

35. Light Microscopes
Uses light and lenses to enlarge an image of an object
Simple: only one lens
Compound: two or more lenses
Compound microscope
First magnification by ocular lens
Second magnification by objective lens
Total magnification= ocular X objective lens magnification

36. Light Microscope Cont’d
Can enlarge images by 1,500x original size
Resolution: 0.2 micrometers
You can see points on an object that are at least 0.2 micrometers apart
Some cells must be stained with a dye in order to see detail

37. Electron Microscopes
Use a magnetic field to focus a beam of electrons through an object or onto an object’s surface
Magnifies up to 100,000x
Resolution: 0.2 nanometers ( m)

38. Electron Microscopes Cont’d
Two kinds of electron microscopes
SEM (scanning electron microscope)
Studies an object’s surface
TEM (transmission electron microscope)
Studies extremely small things
Objects are embedded in plastic and sliced very thin
ONLY dead things can be viewed

39. Using Microscopes Health care Other uses
Use in surgeries- can see area in greater detail
Analyze bodily fluids (blood and urine)
Other uses
Forensic scientists- crime scenes
Paleontologists- use to help with fossils

40. Ch1 L.3 Homework p. 31 1-7 Study for quiz Ch1 L.3 Outline Ch1 L.3
Study for test Ch1