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 _______________________________________