Chapter 1The Science of Biology
How Scientist WorkScientific Method
1. Asking a question 2. Forming a hypothesis 3. Setting –up a controlled experiment 4. Recording & Analyzing Results 5. Drawing a conclusion
Evaluate hypothesis – support or reject
6. Publishing & Repeating Investigations
Controlled Experiments
_________________________ Whenever possible, a hypothesis should be tested by
an experiment in which only one variable is changed at a time. All other variables should be kept unchanged, or CONTROLLED.
_____________________ The variable that is deliberately changed
______________________ The variable that is observed & that changes in response to
the manipulated variable.
Spontaneous Generation
Ex. People would write recipes for living things.
Francisco Redi tested this hypothesis w/ the meat & fly experiment
OBSERVATIONS: Flies land on meat that is left uncovered. Later, maggots appear on the meat.
HYPOTHESIS: Flies produce maggots.PROCEDURE
Controlled Variables:jars, type of meat,location, temperature,time
Manipulated Variables:gauze covering thatkeeps flies away from meat
Uncovered jars Covered jars
Several days pass
Maggots appear No maggots appearResponding Variable: whether maggots appear
CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur.
Section 1-2
Figure 1-8 Redi’s Experiment on Spontaneous Generation
Gravy is boiled. Flask isopen.
Gravy is teeming with microorganisms.
Gravy is boiled. Flask issealed.
Gravy is free of microorganisms.
Section 1-2
Figure 1-10 Spallanzani’s Experiment
Biogenesis
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Early scientists debated Spontaneous generation & Biogenesis
Until Louis Pasteur Experiment with flasks of straight and curved necks &
bacteria entering these flasks demonstrated that life comes from life
Broth is boiled. Broth is free ofmicroorganismsfor a year.
Curved neckis removed.
Broth is teeming with microorganisms.
Section 1-2
Figure 1-11 Pasteur’s Experiment
Broth is boiled. Broth is free ofmicroorganismsfor a year.
Curved neckis removed.
Broth is teeming with microorganisms.
Section 1-2
Figure 1-11 Pasteur’s Experiment
Broth is boiled. Broth is free ofmicroorganismsfor a year.
Curved neckis removed.
Broth is teeming with microorganisms.
Section 1-2
Figure 1-11 Pasteur’s Experiment
Broth is boiled. Broth is free ofmicroorganismsfor a year.
Curved neckis removed.
Broth is teeming with microorganisms.
Section 1-2
Figure 1-11 Pasteur’s Experiment
When are experiments not possible?
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Theory
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Video 1
Video 1
It’s Alive!, Part 1
Characteristics of Living things
1. Made up of cells 2. Reproduce
________________________ Two cells from different parents unite to produce the 1st cell
of the new organism. ________________________
The new organism has a single parent
3. Universal Genetic code _________
4. Grow & develop 5. Obtain & use energy
________________ The building up or breaking down of materials
6. Respond to their environment __________________
Signal which an organism to. Ex. Light or temperature
___________________ Maintaining a constant internal condition
7. Change over time ________________
Video 2
Video 2
It’s Alive!, Part 2
Organism
Groups ofCells
Cells
Molecules
Individual livingthing
Tissues, organs,and organ systems
Smallest functionalunit of life
Groups of atoms;smallest unit of most chemicalcompounds
Bison
Nervous tissue Nervous systemBrain
Nerve cell
Water DNA
Section 1-3
Figure 1-21 Levels of Organization continued
Biosphere
Ecosystem
Community
Population
The part of Earththat contains allecosystems
Community and its nonliving surroundings
Populations thatlive together in a defined area
Group of organisms of onetype that live in the same area
Biosphere
Hawk, snake, bison, prairie dog, grass, stream, rocks, air
Hawk, snake, bison, prairie dog, grass
Bison herd
Section 1-3
Figure 1-21 Levels of Organization
Microscopes
Light microscopes 1000x _______________________________________
_______________________________________ Electron microscopes
Produce magnified images by focusing beams of electrons. (can’t use living specimens)
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Laboratory Techniques
Cell culture _______________________________________
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Cell fractionation _______________________________________