Classifying and Exploring Life

Life Science7th 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.o 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 organismo 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?o Structures within the cell have different

functions.

● Growth= increase in sizeo Unicellular organism: cell increases in

sizeo Multicellular organism: grow as the

number of cells increases

● Development= changes that occur in an organism in its lifetimeo Cells become specialized (skin cells vs

muscle cells)o Dramatic changes= tadpole to frog or

caterpillar to butterfly

Growth and Development

Reproduction● The process by which one organism

makes one or more new organismso Necessary in order for living organisms to continue to

exist

● NOT ALL ORGANISMS REPRODUCE THE SAME WAYo Some just divide to become two where there was

oneo Some can reproduce without a mate (asexual

reproduction)o 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

o Stimulus: hunger; Reaction: look for food

o Stimulus: thirst; Reaction: look for water

● External stimulio 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?

o Temperature: Body temperature is 37C or 98F Shift= sweat or shiver to get

back to normalo Water

Too much: go to the bathroom a lot

Too little: retain watero 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 timeso 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:

o What were your responses when you were warned?o What were your responses when you were not warned?o Were your reactions reflex or responses?

Use Energy

● Everything you do requires energy

● Where does it come from?o Suno 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

groupso Document what you used to organize the items

● Start over and use a different characteristic to re-organize your items into two groupso Document what you used to organize the items

● Let’s discuss: o What did you use to separate the items?o Why do you think it’s important for scientists to have rules for

organizing items?

Classifying Living Things

● How are things organized?o How is your house organized?o 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 structureso Two main groups: Animale vs

Vegetabile kingdom

● This has since been improved into five kingdoms by Robert H Whittakero Monera, Protista, Plantae, Fungi and

Animalia

Kingdoms

Determining Domains● Classification method is

called systematicso Uses information about the

organism to classify them Cell type, habitat, food

and energy sources, features and ancestors

● Three domains to classify BEFORE kingdomso Bacteria, Archaea or Eukarya

Scientific Names● Use binomial

nomenclature to name organismso Two-word scientific nameo Genus + Species

Genus: group of similar species

Species: group of organisms with similar traits that can produce fertile offspring 1. What do you notice about the taxonomic groups as you go

down the table?2. 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 organismo 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 worldwideo Why is it important to have scientific

names?

Classification tools● Dichotomous keys:

series of descriptions arranged in pairs that allows identification of an organismo 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

6.3.

1. 2. 5.4.

Classification tools cont’d● Cladograms:

branched diagram that shows relationships among organisms, including ancestors.o Each branch follows a

new characteristico Each characteristic is

present in all organisms to the right of it

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)o 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 objecto Simple: only one lenso Compound: two or more lenses

● Compound microscopeo First magnification by ocular lenso Second magnification by

objective lenso Total magnification= ocular X

objective lens magnification

● Can enlarge images by 1,500x original size

● Resolution: 0.2 micrometerso 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

Light Microscope Cont’d

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 o Resolution: 0.2

nanometers (.000000002m)

Electron Microscopes Cont’d● Two kinds of electron

microscopeso SEM (scanning electron

microscope) Studies an object’s surface

o 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

o Use in surgeries- can see area in greater detail

o Analyze bodily fluids (blood and urine)

● Other useso Forensic scientists-

crime sceneso 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