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7th Grade Science
Charpter 1 Classifying and Exploring Life
Term | Definition |
---|---|
organisms | things that have all the characteristics of life |
6 characteristic to all living things | 1. organization 2. growth and development 3. reproduction 4. responds to stimuli 5. homeostasis 6. energy |
cell | the smallest unit of life |
unicellular | living things that are made of only one cell (gets bigger by cell getting bigger) |
multicellular | living things that are made of two or more cells (gets bigger by making more cells) |
sexual reproduction | requires 2 parents...offspring is a mix of parents genetics |
asexual reproduction | requires 1 parent...offspring is a clone of parent |
response | reaction to a stimulus |
stimulus | anything that causes a change in an organism |
internal stimuli | stimuli that organisms react to from inside their body ex: hunger, thirst, body temperature, stress |
external stimuli | stimuli that organisms react to from outside their body or surrounding environment ex: light, heat, noise, danger |
homeostasis | an organism's ability to maintain steady internal conditions when outside conditions change |
producer | make their own energy |
consumer | eat to get energy |
organization levels throughout the organism | cells -> tissue -> organ -> organ systems -> organism |
Characteristic #1 - organization | living things have specialized structures with specialized functions |
Characteristic #2 - growth and development | living things grow by increasing cell size and/or increasing cell number |
Characteristic #3 - reproduction | living things make more living things through the process of reproduction |
Characteristic #4 - respond to stimuli | living things adjust and respond to changes in their internamland external environments |
Characteristic #5 - homeostasis | living things maintain stable internal conditions |
Characteristic #6 - use of energy | living things use energy for all the processes they perform |
binomial nomenclature | gives each organism a two-word scientific name |
species | is a group of organisms that have similar traits and are able to produce fertile offspring |
genus | is a group of similar species |
dichotomous key | is a series of descriptions arranged in pairs that leads the user to the identification of an unknown organism |
cladogram | is a branched diagram that shows the relationships among organisms, including common ancestors |
light microscope | use light and lenses to enlarge an image of an object |
compound microscope | a light microscope that uses more than one lens to magnify an object (eyepiece and objective lens) |
electron microscope | use a magnetic field to focus a beam of electrons through an object or onto an object's surface |
transmission electron microscope (TEM) | used to study extremely small items; thin slice of a dead organism |
scanning electron microscope (SEM) | used to study an objects surface...produces a 3-dimensional image |
Anton van Leeuwenhoek | In 1600's made one of the first microscopes |
Robert Hooke | in 1700's he observed and named cells using a microscope |
total magnification | eye lens x objective lens ex: low power = 40x ex: middle power = 100x ex: high power = 400x |