1. Table of Contents What Is Life? Classifying Organisms
Domains and Kingdoms
The Origin of Life

2. Section 1 “What is Life?” Characteristics of Living Things
Organisms – (living things) all contain certain characteristics that scientists use to identify them as living.
These characteristics include:
Made of cells
Chemical makeup
Use energy
Respond to their surroundings
Grow and develop
Reproduce

3. Cellular Organization
Cell – the basic unit of structure and function in an organism
Cells are very small and can only be seen by a microscope
Living things can be unicellular or multicellular
Unicellular organisms – are made of only one cell (single-celled)
Ex: bacteria, some protists
Multicellular organisms – are made of many cells
The cells are specialized (have a specific job)
Ex: animals, plants, insects, etc.

4. Chemical Makeup
All cells are made up of chemicals, the most abundant being water.
Other chemicals include, carbohydrates, proteins, lipids, and nucleic acids

5. Energy Use
The cells of an organism need energy in order to grow, reproduce and to complete their job.
What are some ways your body uses energy?

6. Response to Surroundings
Stimulus – a change in an organism’s surroundings that causes it to react.
Ex. changes in temperature, light, sound, etc.
Response – an action or change in behavior that is a reaction to a stimulus.
Ex: Stimulus – loud bang; Response – jump

7. Growth and Development
Growth – an organism becomes larger in size (growing as a cell or creating new cells)
Development – process of change that occurs in an organisms life to create a more complex organism
Ex: sunflower seed turns into a sunflower

8. Reproduction
Reproduction – the ability to produce offspring similar to the parent(s)
Ex: Apple seeds produce apple trees (which contain mores seeds)

9. Life Comes from Life
We know today that all living things have to come from other living things through reproduction. However, hundreds of years ago scientists believed differently
Spontaneous generation – idea that living things were created from non-living things
Ex: Scientists believed that raindrops could spontaneously generate into earth worms and that rotten meat spontaneously generated into flies.

10. Redi’s Experiment
Francesco Redi - (1600’s) attempted to disprove the theory of spontaneous generation by designing a controlled experiment that would show that flies do not come from rotten meat.

11. Redi’s and Pasteur’s Experiments
- What Is Life?
Redi’s and Pasteur’s Experiments
Click the Active Art button to open a browser window and access Active Art about Redi’s and Pasteur’s experiments.

12. - What Is Life?
Life Comes From Life
Francesco Redi designed one of the first controlled experiments. In his experiment, Redi showed that flies do not spontaneously arise from decaying meat.

13. Redi’s Experiment
Controlled experiment – two tests that are the same in all factors, except one….known as the variable
Redi placed a slice of meat into two jars. However, he only covered one jar (the variable).
Result: Flies formed in the uncovered jar only, showing that the flies did not come from the meat.
Even after Redi’s experiment many people still continued to believe spontaneous generation. They thought that because Redi blocked the air the flies couldn’t develop

14. Pasteur’s Experiment
Louis Pasteur – (1800’s) designed an experiment to finally disprove spontaneous generation.
Pasture filled two flasks with broth. The flasks had curved necks which would remain open but would not allow bacteria to enter.
Pasture boiled one flask to kill any living bacteria already in the broth (this was his variable)

15. - What Is Life?
Life Comes From Life
Louis Pasteur’s carefully controlled experiment demonstrated that bacteria arise only from existing bacteria.

16. The Needs of Living Things
All living things must satisfy their basic needs for food, water, living space, and stable internal conditions.
Food – serves as a source of energy that all living things need.
Autotrophs – organisms make their own food
Ex: Plants, Some bacteria (Cyanobacteria)
Heterotrophs – organisms that cannot make their own food, and must take food in from outside the body.
Ex: Animals, Mushrooms, Slime molds, etc.

17. The Needs of Living Things
Water – is needed for living things to survive
Most organisms can only go a few days without water (humans approx. 3 days)
Organisms need it to break down food, grow, move substances within their bodies, and reproduce.
Makes up 90% of the liquid part of the human body or 70% of total body mass
Water dissolves chemicals and nutrients and carries them throughout the body.

18. The Needs of Living Things
Living Space – is another necessity of living organisms
An area that provides shelter from the elements, food, and water
Many organisms have to compete for space (within a species and with other species)

19. The Needs of Living Things
Stable Internal Conditions – an organism must keep the conditions within their body stable even though the environment they live in may change
Homeostasis – is the maintenance of a stable internal condition
Ex: Body temperature, pressure, amount of chemicals, amount of water, etc.

20. The Characteristics of Living Things
- What Is Life?
The Characteristics of Living Things
Click the Video button to watch a movie about the characteristics of living things.

21. Section 2 Classifying Organisms
Why do scientists classify?
Because there are a tremendous number of different organisms, scientists needed to find an organized way of studying all of them.
Classification – is the process of grouping things based on similarities
Biologists use classification to organize living things into groups so that the organisms are easier to study.

22. Taxonomy – the scientific study of how living things are classified
Scientists learn more about an organism once it is classified.
Ex: If an organism is classified as a bird, scientists know it has feathers, wings, and a beak.

23. The naming system of Linnaeus
Carolus Linnaeus – (1750’s) Swedish scientist that devised a system of naming organisms that is still in use today
Binomial nomenclature – or scientific name is the naming system used by Linnaeus, means “two names”

24. The naming system of Linnaeus
Genus – the first word in an organism’ s scientific name
Contains similar closely related organisms
Ex: pumas, marbled cats, house cats all belong to the genus Felis
Species – a group of similar organisms that can mate with one another and produce fertile offspring.
Second word of an organism’s scientific name
Ex: humans belong to the genus and species: Homo sapiens

25. Using Binomial Nomenclature
A complete scientific name is usually written in italics. Sometimes the names will be underlined.
The first word of the scientific name (the genus name) is always capitalized. While the second name (the species name) is always lower case
Canis lupus

26. All scientific names come from the Latin language
All scientific names come from the Latin language. Three reasons for this:
Latin is a dead language; therefore meanings of words will not change.
By using Latin scientists do not favor one country over another.
Latin is a descriptive language.
Organisms also have “common names.” However, in different areas they may be called different names, which is confusing.
Ex: The ground hog; also known as the woodchuck and whistlepig has only one scientific name, Marmota monax.

27. Levels of Classification
- Classifying Organisms
Levels of Classification
As you move down the levels of classification, the number of organisms decreases. The organisms at lower levels share more characteristics with each other.

28. Levels of Classification
The groupings include (from largest to smallest)
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
“Did King Phil Come Over From Great Spain?”

29. Aristotle and Classification
- Classifying Organisms
Aristotle and Classification
Many hundreds of years before Linnaeus, a Greek scholar named Aristotle developed a classification system for animals. Aristotle first divided animals into those he considered to have blood and those he did not. This graph shows Aristotle’s classification system for “animals with blood.”

30. Aristotle and Classification
- Classifying Organisms
Aristotle and Classification
Reading Graphs:
Into how many groups were these animals classified? 3

31. Aristotle and Classification
- Classifying Organisms
Aristotle and Classification
Interpreting Data:
Which group made up the largest percentage of animals?
Animals that fly

32. Aristotle and Classification
- Classifying Organisms
Aristotle and Classification
Calculating:
What percentage of these animals either fly or swim?
78%

33. Aristotle and Classification
- Classifying Organisms
Aristotle and Classification
Inferring:
In Aristotle’s classification, where would a cow be classified? A whale?
Cow- animals that walk, run, or crawl; whale- animals that swim.

34. Aristotle and Classification
- Classifying Organisms
Aristotle and Classification
Predicting:
Would Aristotle’s classification system be used today? Explain.
Possible answer: This system includes only three categories, so it may not be very useful today. It also does not match that of modern scientists, who use characteristics other than movement to classify animals. For example, frogs and lions belong to very different groups.

35. Taxonomic Keys
Scientists have helped the average person learn more about organisms by creating field guides and taxonomic keys.
Field guild - gives drawings of various organisms along with a written description of their characteristics and habitat.
Taxonomic Key – consists of a series of paired statements that describe the physical characteristics of different organisms
Are useful tools for determining the identity of organisms

36. - Classifying Organisms
Taxonomic Keys
Taxonomic keys are useful tools for determining the identity of organisms.

37. More on Classifying Living Things
- Classifying Organisms
More on Classifying Living Things
Click the PHSchool.com button for an activity about classifying living things.

38. Section 3 Domains and Kingdoms
There are currently 3 domains in the classification system.
Organisms are placed into domains and kingdoms based on their:
Cell type
Ability to make food
Number of cells in their body

39. - Domains and Kingdoms
Three Domains of Life
In the three-domain system of classifications, all known organisms belong to one of three domains–Bacteria, Archaea, or Eukarya.

40. Domain Bacteria Members of this domain are all prokaryotes.
Prokaryotes – organisms whose cells do not contain a nucleus
Nucleus – a dense area in a cell that contains nucleic acids (chemical instructions for the cell)

41. Domain Archaea Unicellular prokaryotes that live in extreme climates
Found in hot springs, molten rock, and freezing arctic climates
Similar to bacteria, but have a slightly different chemical makeup

42. Domain Eukarya Members of this domain are all Eukaryotes.
Eukaryotes – organisms whose cells contain a nucleus
Members of this domain are classified into one of four categories:
Protists – a eukaryotic organism that can not be classified a plant, animal, or fungus.
Some are autotrophs and some are heterotrophs
Most are unicellular, but a few are multicellular
“Odds and ends” group

43. Domain Eukarya
Fungi – multicellular eukaryotes that can not move and can not make their own food (heterotrophs).
Ex: Molds, mushrooms, mildew, yeast (unicellular)
Plants – multicellular eukaryotes that can not move, but can make their own food (autotrophs)
Provide most of the food for heterotrophs on land.
Animals – multicellular eukaryotes that can move, but can not make their own food (heterotrophs)

44. Comparing and Contrasting
- Domains and Kingdoms
Comparing and Contrasting
As you read, compare and contrast the characteristics of organisms in domains Bacteria, Archaea, and Eukarya by completing a table like the one below.
Characteristics of Organisms
Domain or Kingdom
Cell Type and Number
Able to Make Food?
Prokaryotes; unicellular
Some are able to make food
Bacteria
Prokaryotes; unicellular
Some are able to make food
Archaea
Eukarya:
Protists
Eukaryotes; unicellular or multicellular
Some are able to make food
Fungi
Eukaryotes; unicellular or multicellular No
Plants
Eukaryotes; multicellular
Yes
Animals
Eukaryotes; multicellular No

45. Click the SciLinks button for links on kingdoms.
- Domains and Kingdoms
Links on Kingdoms
Click the SciLinks button for links on kingdoms.

46. Section 4 The Origin of Life
The Atmosphere of Early Earth
The Earth is believed to be about 4 billion years old
On ancient Earth, water vapor, carbon dioxide, and methane were probably the most abundant gases in the atmosphere. There were frequent volcanic eruptions, earthquakes, and violent storms
Scientists believe that life began about 3.5 billion years ago.

47. Modeling Conditions on Early Earth
The biggest question in science today is how did life arise?
Stanley Miller – (1953) performed an experiment where he mixed water, gases (found on early earth), and sent electricity through the mixture (to represent lightening)
After a few days the mixture began forming the building blocks of proteins, which are a part of the cell
However, they were never able to form life. No human has ever been able to form living thing from a non-living thing.

48. The First Cells
Many scientists think that these chemicals proteins, lipids, nucleic acids, and carbohydrates formed together to form the first cells.
Support from fossil evidence
Fossil – is a trace of an ancient organism that has been preserved in rock or other substances for hundreds, thousands, or millions of years.
Scientists have found fossil evidence to help support many of their theories about the origin of life.

49. Links on the Origin of Life
Click the SciLinks button for links on the origin of life.

50. Modeling Conditions on Early Earth
- The Origin of Life
Modeling Conditions on Early Earth
Click the Video button to watch a movie about modeling conditions on early Earth.

51. Graphic Organizer Living Things Food Homeostasis Water Living space
need
Food
Homeostasis
Water
Living space
made by
to provide
Autotrophs
Shelter
Food & water
eaten by
Heterotrophs