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

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

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.

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

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?

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

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

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

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.

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.

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.

- 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.

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

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)

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

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.

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.

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)

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.

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.

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.

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.

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”

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

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

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.

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.

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?”

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.”

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

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

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

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.

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.

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

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

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

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

- 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.

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)

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

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

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)

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

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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.

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.

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.

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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.

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