Classifying and Exploring Life Life Science 7th grade

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

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

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?

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

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

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.

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

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

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

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

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

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?

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

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

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

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

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?

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

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

Kingdoms

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

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

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?

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

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

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.

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

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

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?

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

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

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

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

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

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 (.000000002m)

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

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

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