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CHARACTERISTICS OF LIFE
1) LIVING THINGS ARE MADE FROM THE SAME BUILDING BLOCKS, ORGANIZED INTO CELLS
LEVELS OF ORGANIZATION
atoms
molecules nonliving = abiotic
cells living = biotic
tissues
organs
organism = living thing
Human Brain Nerve Cell
ORGANISM = living thing
Species = similar organisms, interbreed
in the wild, only with each other
Species = reproductively isolated group
of organisms
Species = one kind of organism
population = all members of the same species,
that live together in same area, at same time
community = all populations (plants & animals)
that live together in same area, at same time
physical environment = non living (abiotic)
air, rocks, soil, water, light, climate
ecosystem = community + physical environment
biosphere = all organisms on Earth
= all communities on Earth
= all life on Earth
CHARACTERISTICS OF LIFE
2) ORGANISMS GROW & MAINTAIN THEIR ORGANIZATION BY GETTING MOLECULES & ENERGY FROM THE ENVIRONMENT
Autotrophs = self feeding= self feeding
Energy Flow: Sunlight Sunlight Food Molecules Food Molecules Work Work
HeatHeat
= plants, algae, some bacteria= plants, algae, some bacteria
Heterotrophs = other feeding (eaters)= animals, fungi, bacteria
Energy Flow: Food Molecules Work (stay organized)
Heat (to atmosphere)(to atmosphere)
CHARACTERISTICS OF LIFE
3) ORGANISMS MOVE OR OTHERWISE RESPOND TO CHANGES (STIMULI) IN THE EXTERNAL ENVIRONMENT
Response = Behavior
CHARACTERISTICS OF LIFE
4) ORGANISMS REPRODUCE &
PASS ON THEIR DNA TO THEIR OFFSPRING
DNA = Instructions
CHARACTERISTICS OF LIFE
5) GROUPS OF ORGANISMS SHOW VARIATIONS & EVOLVE, OR CHANGE, TO ADAPT TO THEIR ENVIRONMENT
Source of variations = mutations,which are changes in DNA
and new combinationscreated by sexual reproduction
LIFE MODEL
Survival= First Priority for Resources Is Stay Alive
Growth = Extra Resources must be available
Reproduction = Extra Resources must be available
Science
SCIENCE = derived from a Latin verb meaning “to know”
= seeks natural causes for natural phenomena
Includes two forms of inquiry;
1) Discovery (descriptive) science
2) Hypothesis-driven science
Discovery Science
Observations of nature
Human genome project
Inductive conclusion is a generalization based on many specific observations
Ex. “All organisms made of one or more cells”
Hypothesis-driven Science
Scientific Method = series of steps that form a formal process of inquiry
Deductive conclusion is using the general premise to predict a specific result
Follows “if…then” logic, i.e. if all organisms are made of cells, & humans are organisms, then humans are made of cells.
HYPOTHESIS
Can be shown to be false
Can NOT be proved true, only supported by results
Example:
I am the fastest runner in the world
Fly Mimicry Experiment
OBSERVATIONS
Jumping Spiders
1) stalk and pounce on flies
2) wave their legs to scare off other jumping spiders
Jumping Spider
Fly Mimicry Experiment
OBSERVATIONS
Spider-mimicking flies
1) have markings on their wings that look like
spider’s legs
2) wave their wings (false legs) at spiders
Fly Mimicry Experiment
QUESTION #1
Does mimicry (looking like jumping spiders) actually turn real jumping spiders away?
Fly Mimicry Experiment
HYPOTHESIS
Mimicry (looking like jumping spiders) does turn real jumping spiders away.
Fly Mimicry Experiment
Control Group (of organisms) =
Normal Spider-mimicking flies
Experimental or Treatment Group (of organisms) =
Flies with wing markings or “legs” masked
Fly Mimicry Experiment
Manipulated or Independent Variable = difference between two groups
that is being tested
= looking like jumping spiders
Fly Mimicry Experiment
Responding (Dependent) Variable = results that may be different between the two groups being compared
Responding (Dependent) Variable = Pounce rate (% of trials in which spiders jumped on the fly)
Fly Mimicry Experiment
Controlled Variables or Constants =
all factors that are the same between the two groups
Fly Mimicry Experiment
Results = spiders pounced on treatment group more than controls, as shown on graph
Conclusion = the results support the hypothesis that mimicry (looking like jumping spiders) did turn jumping spiders away
Fly Mimicry Experiment
OBSERVATIONS
Jumping Spiders
1) stalk and pounce on flies
2) wave their legs to scare off other jumping spiders
Jumping Spider
Fly Mimicry Experiment
OBSERVATIONS
Spider-mimicking flies
1) have markings on their wings that look like
spider’s legs
2) wave their wings (false legs) at spiders
Fly Mimicry 2nd Experiment
QUESTION #2
Are both types of mimicry;
(acting & looking like jumping spiders)
required to turn real jumping spiders
away?
Fly Mimicry 2nd Experiment
HYPOTHESIS
Both types of mimicry (acting & looking) like jumping spiders) are required to turn real jumping spiders away.
Fly Mimicry 2nd Experiment
Manipulated Variables = difference between two groups that are being tested
Mimicry = looking like jumping spiders
= wing markings
Mimicry = acting like jumping spiders
= wing waving
Fly Mimicry 2nd ExperimentFive Test Groups of Flies
1) Normal spider mimics
2) Mimics w/ mimic wing transplants
3) Mimics w/ housefly wing transplants
4) Houseflies w/ mimic wing transplants
5) Normal houseflies
Fly Mimicry 2nd Experiment
Dependent Variable = results that may be different between the two groups being compared
Dependent Variable = actual number of stalk and attack responses by spiders
Fly Mimicry 2nd Experiment
Results = spiders stalked and attacked groups without both types of mimicry more often than groups with both types
Conclusion = the results support the hypothesis that both types of mimicry (acting & looking like jumping spiders) are required to turn jumping spiders away
According to the National Academy of Sciences,Some scientific explanations are so well established that no new evidence is likely to alter them. The explanation becomes a scientific theory. In everyday language a theory means a hunch or speculation. Not so in science. In science, the word theory refers to a comprehensive explanation of an important feature of nature that is supported by many facts gathered over time. Theories also allow scientists to make predictions about as yet unobserved phenomena.
Scientific Theory
According to Stephen Hawking, "a theory is a good theory if it satisfies two requirements: It must accurately describe a large class of observations on the basis of a model which contains only a few arbitrary elements, and it must make definite predictions about the results of future observations".
Isaac Newton's theory of universal gravitation is a physical law describing the gravitational attraction between bodies with mass.
It states the following:
Every object attracts every other object by a force pointing along the line intersecting both objects. The force is proportional to the product of the two masses and inversely proportional to the square of the distance between the objects.
Is it supported by many facts gathered over time?
Does it allow scientists to make predictions about as yet unobserved phenomena?