Chapter 1 - The Science of Biology

1-1 What is Science?

• Goal= investigate and understand the natural world, to explain events, and to use those explanations to make useful predictions.

• Scientfiic Method

• Steps: observe to gather data

- observation= gathering data

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- hypothesis= proposed explanation for a set of observations

a. can be tested by experiment or data

b. disproved or supported by data

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• Review:

1. Why is it important for you to know about biology?

2. Why is skepticism considered a valuable quality in a scientist?

3. What is the difference between qualitative and quantitative data?

1-2 How Scientists Work• Spontaneous generation- old theory that

life could come from nonliving matterex: meat left on counter will grow maggots

• Francesco Redi (1668)- created new hypothesis that flies laid eggs on the meat which hatched maggots

– Used scientific method to create an experiment

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State the Problem

Form a Hypothesis

Set Up a Controlled Experiment

Record Results

Analyze Results

Draw a Conclusion

Publish Results

Designing an experiment

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• A Controlled Experiment is an experiment in which only one variable is changed at a time.

- Controlled variables – kept the same

- Manipulated variable – variable that is changed

- Responding variable – what is observed to changed in response to manipulated variable

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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 appear

Responding Variable: whether maggots appear

CONCLUSION: Maggots form only when flies come in contact with meat. Spontaneous generation of maggots did not occur.

Figure 1-8 Redi’s Experiment on

Spontaneous Generation (1668)

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• Repeating Investigations- controlled experiments should be reproducible

- three scientists supported Redi’s conclusions with additional experiments: Needham, Spallanzani, and Pasteur

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Gravy is boiled. Flask isopen.

Gravy is teeming with microorganisms.

Gravy is boiled. Flask issealed.

Gravy is free of microorganisms.

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.

Figure 1-11 Pasteur’s Experiment

• 1864- Convinced scientists that spontaneous generation was invalid

• Impacted industry and medical research1-2

• Alternative experiments

- Field studies view animals in environment

- Theory – well-tested hypothesis that explains a broad range of observations

-ex: theory of plate tectonics

- Biogenesis – “generating from life”; theory resulting from multiple experiments previously discussed 1-2

• Major Discoveries in History of Biology1543 Andreas

VesaliusDetailed study of human anatomy

1628 William Harvey

Circulation of blood

1673 Anton van Leeuwenhoek

Perfects simple microscope to observe cells

1859 Charles Darwin

Publishes theory of natural selection

1881 Louis Pasteur Develops vaccine against anthrax

1953 Watson & Crick

Determined structure of DNA1-3

• Review:

1. What was the manipulated variable in Redi’s experiment?

2. What was special about Pasteur’s apparatus?

3. How does a hypothesis become a theory?

If you were to make a list of characteristics of a living thing, what would be on it?

1-3 Studying Life

• Biology- the science that seeks to understand the living world.

• Characteristics of living thingsCharacteristic Examples

Living things are made up of units called cells.

Many microorganisms consist of only a single cell. Animals and trees are multicellular.

Living things reproduce. Maple trees reproduce sexually. A hydra can reproduce asexually by budding.

Living things are based on a universal genetic code.

Flies produce flies. Dogs produce dogs. 1-3

Characteristic Examples

Living things grow and develop.

Flies begin life as eggs, then become maggots, and then become adult flies.

Living things obtain and use materials and energy.

Plants obtain their energy from sunlight. Animals obtain their energy from the food they eat.

Living things respond to their environment.

Leaves and stems of plants grow toward light.

Living things maintain a stable internal environment.

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

Taken as a group, living things change over time.

Plants that live in the desert survive because they have become adapted to the conditions of the desert. 1-3

• Important terms

-Cell- collection of living matter enclosed in a barrier

-Sexual reproduction- two parents

-Asexual reproduction- one parent

-Metabolism- all chemical reactions in an organism

-Stimulus- signal to which an organism responds

-Homeostasis- process by which organisms maintain internal conditions 1-3

• Branches of Biology

-Zoologists- study animals

-Botanists- study plants

-Paleontologists- study ancient life

-Molecular biologists – study the chemistry of living organisms

-Population biologists – study the interactions of animals

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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

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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• Review:

1. Which characteristics of life does an automobile have? Why isn’t it considered a living thing?

2. In what context have you heard about metabolism before today?

3. What is another type of biologist not mentioned in the notes, and what do they study?

Click to play “It’s Alive Part 1”

Click to play “It’s Alive part 2”

1-4 Tools and Procedures

• The METRIC system- decimal system of measurement whose units are based on multiples of ten

Kilo Hecto Deka base deci centi milli

Km Hm Dm m

meter

dm cm mm

0.001 0.01 0.1 1 10 100 1000

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Water Released and Absorbed by Tree

TimeAbsorbedby Roots

(g/h)

Releasedby Leaves

(g/h)

8 AM

10 AM

12 PM

2 PM

4 PM

6 PM

8 PM

5

2

10

14

9

6

4

1

1

12

17

16

10

3

Water released by leaves

Water absorbed by roots

Rel

ati

ve

Rat

es

(g/h

)

20

Time

0

15

10

5

8 AM 10 AM 12 PM 2 PM 4 PM 6 PM 8 PM

Analyzing Biological Data

• tables and graphs are used to view trends and patterns in the data

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Microscopes• Light microscopes- produce magnified images

by focusing visible light rays– Mag 1000 times

• Electron microscopes- produce magnified images by focusing beams of electrons– Mag 1,000,000 times but require vacuum– Transmission electron microscopes (TEMs)-

shine beam of electrons through thin specimen

– Scanning electron microscopes (SEMs)- scan the surface of specimen with electrons to make 3D image

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• Review:

1. How many meters are in a kilometer?

2. How many centigrams are in a gram?

3. What must always be included on a graph?

4. TEMs and SEMs require a vacuumed environment. How does this affect the specimen?