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Chapter 1

The Science of Biology

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1–1What Is Science?A. Science is an organized way of using evidence to learn about the world.

B. The goal of science is to investigate and understand the natural world, explain events in the natural world, and make useful predictions.

C.Science is a body of knowledge that has been built up by scientists after centuries of using the scientific method.(We stand upon the shoulders of giants-Isaac Newton)

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Section Outline

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1-2 How Scientists WorkScientific Method1. Observation- Gather information (data; Quantitative & Qualitative)

about something in an orderly way and ask a question2. Form a hypothesis- a proposed scientific explanation for a set of

observations; a testable educated guess3. Controlled Experiment- includes variables (factors that change)

a. Manipulated Variable (Independent)- variable that is deliberately changedb. Responding Variable (Dependent)- variable that is observed and changes in response to the manipulated variablec. Controlled Variable (Control)- variable that is kept the same for use as a comparisond. In a good experiment, only one variable is manipulated at a time.

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1-2 How Scientists WorkScientific Method continued

4. Recording and Analyzing Results- collecting data (information obtained from experiments)

a. In science, we must be able to replicate our experiments. Recording our process and data accurately is a must.

b. By recording our data we are able to build upon past knowledge

5. Drawing a Conclusion- using the evidence to validate or refute the hypothesis.

Sometimes it is a good thing to be wrong! Every experience is a learning experience!

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Flow Chart “Designing an Experiment”

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Flowchart

State the Problem

Form a Hypothesis

Set Up a Controlled Experiment

Record Results

Analyze Results

Draw a Conclusion

Publish Results

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1-2 How Scientists Work

Theory- a well tested explanation that unifies a broad range of observations. Sometimes a particular hypothesis becomes so supported from numerous investigations scientists consider it a theory.

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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.

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Figure 1-8 Redi’s Experiment on Spontaneous Generation

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Gravy is boiled. Flask isopen.

Gravy is teeming with microorganisms.

Gravy is boiled. Flask issealed.

Gravy is free of microorganisms.

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Figure 1-10 Spallanzani’s Experiment

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Broth is boiled. Broth is free ofmicroorganismsfor a year.

Curved neckis removed.

Broth is teeming with microorganisms.

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Figure 1-11 Pasteur’s Experiment

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1-3 Studying LifeCharacteristics of Living Things

1. Made Up of Cells- smallest unit of an organism considered alive2. Reproduction- producing new organisms

a. Sexual- cells from two different parents uniteb. Asexual- new organism comes from only one parent

3. Based on a Genetic Code- directions for life processes come from DNA

4. Growth and Development5. Need for Materials and Energy- metabolism is the combination of

chemical reactions happening in your body6. Response to the Environment- A stimulus is a signal to which an

organism responds. A reaction to a stimulus is called a response.7. Maintaining Internal Balance (homeostasis)8. Evolution- change over time

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Characteristic ExamplesLiving things are made up of units called cells.Living things reproduce.

Living things are based on a universal genetic code.

Living things grow and develop.

Living things obtain and use materials and energy.

Living things respond to their environment.Living things maintain a stable internal environment.

Taken as a group, living things change over time.

Many microorganisms consist of only a single cell. Animals and trees are multicellular.Maple trees reproduce sexually. A hydra can reproduce asexually by budding.Flies produce flies. Dogs produce dogs. Seeds from maple trees produce maple trees.Flies begin life as eggs, then become maggots, and then become adult flies.Plants obtain their energy from sunlight. Animals obtain their energy from the food they eat.

Leaves and stems of plants grow toward light.

Despite changes in the temperature of the environment, a robin maintains a constant body temperature.

Plants that live in the desert survive because they have become adapted to the conditions of the desert.

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Characteristics of Living Things

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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

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Figure 1-21 Levels of Organization

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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

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Figure 1-21 Levels of Organization continued

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1–4Tools and Procedures1. A Common Measurement System-

Metric System- decimal system of measurement whose units are based on multiples of 10

2. Microscopes (we will learn more in Chapter 7)

1. Compound Light Microscopes- allow light to pass through the specimen and use two lenses

2. Electron Microscopes- use electrons to produce images of specimens (images are1000 times more detailed than light microscope)

D. Laboratory Techniques

1. Cell Cultures- cells are reproduced so they can be studied

2. Cell Fractionation- cells are broken up and the parts are separated for studying individual cell parts.

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Section Outline

Videos

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It’s Alive!, Part 1

It’s Alive!, Part 2

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