Chapter 1

What is Biology?

The Science of Biology

• Science – the process to understand the world around us.

• Biology – the study of life

• Bios means life in Greek

• Logos means study of

• Living things depend on other living and nonliving things.

Biologists Study the Diversity of Life

• Why Study Biology?

• Lead to advances in medical treatment and disease prevention.

• Help preserve species in danger of disappearing

• Teach you how humans function

Characteristics of Living Things

• Sometimes nonliving things have one or more of life’s characteristics, but only when something has all of them can it be considered living.

• Organism – anything that possesses all of the characteristics of life.

• 6 Characteristics of Living Things:

1. Made of cells

• Each cell contains DNA.

2. Reproduction – production of offspring

• Reproduction is not essential for the survival of an individual organism, but it is essential for the continuation of the organism’s species.

• Species – a group of organisms that can interbreed and produce fertile offspring.

3. Grow and develop

• Growth – an increase in the amount of living material and the formation of new structures.

• Development – all of the changes that take place during the life of an organism.

4. Adapt to the environment

• Homeostasis – regulation of an organisms internal environment to maintain conditions suitable for its survival.

5. Adapt and evolve

• Adaptation – any structure, behavior, or internal process that enables an organism to respond to stimuli and better survive in an environment.

• Evolution – the gradual accumulation of adaptations over time.

6. Have a definite life span

The Methods of Biology and Science 

• Scientific Method – common steps that scientists use to gather information and answer questions.

• Scientific Method has 5 steps:

• 1. Collect observations and state the problem.

• Scientists first observe something with one or more of their five senses

• What do you want to find out

2. Form a hypothesis – an explanation for a question or a problem that can be tested.

3. Plan and Perform MULTIPLE Experiments.

• Perform the experiment as many times as possible to reduce the chance of error.

• There are 3 important parts to an experiment.

• Control - the group in which all conditions are kept the same and you can compare your results against

• Variable – condition that changes

• Constant(s) – conditions(s) that stay the same

4. Observe and Record Results.

• Make tables, charts, graphs

• Do you see any patterns or trends?

5. Draw Conclusions

• Does the data support your hypothesis?

• What errors occurred in your experiment?

• What would you do different next time?

• Form a Theory

• Theory – a hypothesis that is supported by a large body of scientific evidence.

• No theory is considered absolute truth.

• As new evidence is uncovered a theory may be revised or replaced.

• It becomes a Law after many years of holding true.

Two Things Involved in Testing

• Independent Variable – the condition in an experiment that is changed by the scientist

• It is the variable you mess with or what you can change

• Goes on the X axis

• Dependent Variable – the condition in an experiment that changes

• The variable you measure or what you can’t directly control.

• Goes on the Y axis

Graphing

• The X axis is horizontal

• The Y axis is vertical

• What Makes a Good Graph?

• Title

• Axis is labeled with units of measurement

• Use all of graph paper

• Key

LINE

GRAPH

Effect of Enzyme Concentration on Enzyme ActivityEnzyme

ConcentrationH2O2

DepthYour Data

TimeYour Data

RateClass Data Avg. Rate

0 units/ml (0%) 100mm 0.0sec 0 mm/sec 0.0mm/sec

20 units/ml (20%) 98mm 31 sec 3.2 mm/sec 2.98mm/sec

50 units/ml (50%) 103mm 18 sec 5.7 mm/sec 5.48mm/sec

80 units/ml (80%) 100mm 14 sec 7.1 mm/sec 7.39mm/sec

100 units/ml (100%) 110mm 12 sec 9.2 mm/sec 8.42mm/sec

Effect of Enzyme Concentration on Enzyme Activity

0

1

2

3

4

5

6

7

8

9

10

0 20 50 80 100

Enyzme Concentration (units/ml)

Enzyme Reaction Rate (mm/sec)

My Results

Class Avg.

BAR

GRAPH

Effect of Enzyme Concentration on Enzyme ActivityEnzyme

ConcentrationH2O2

DepthYour Data

TimeYour Data

RateClass Data Avg. Rate

0 units/ml (0%) 100mm 0.0sec 0 mm/sec 0.0mm/sec

20 units/ml (20%) 98mm 31 sec 3.2 mm/sec 2.98mm/sec

50 units/ml (50%) 103mm 18 sec 5.7 mm/sec 5.48mm/sec

80 units/ml (80%) 100mm 14 sec 7.1 mm/sec 7.39mm/sec

100 units/ml (100%) 110mm 12 sec 9.2 mm/sec 8.42mm/sec

00.5

11.5

22.5

33.5

44.5

55.5

66.5

77.5

88.5

99.5

Enzyme Reaction Rate

(mm/sec)

0 20 50 80 100

Enyzme Concentration (units/ml)

My Results

Class Avg.

Effect of Enzyme Activity on Enzyme Concentration

Energy Sources and UsesNatural

Gas24%

Coal22%

Oil43%

Uranium4%

Other Sources

7%

Natural Gas

Coal

Oil

Other Sources

Uranium

PIE

GRAPH

Kinds of Data

• Quantitative Data

• Experiments that result in counts, measurements, or numerical data

• Data may be used to make a graph or table.

• Qualitative Data

• Observational data that is written descriptions or pictures of what scientists observe.

• It is useful because some phenomena aren’t appropriate for quantitative research.

Microscopes

• Microscopes enable biologists to observe cellular processes and to see details of cell structure.

• 2 important concepts of microscopes:

1. Magnification – to make an image appear larger

2. Resolution - shows details clearly

• Light Microscopes

• Use a beam of light passing through one or more lenses

• Compound light microscopes use two sets of lenses

• Use compound microscopes to study living or nonliving cells

• As magnification increases the resolution decreases.

• Electron Microscope

• Use electrons instead of light

• Can magnify more than light microscopes

• Living cells cannot be viewed

• 2 Types of Electron Microscopes

1. Transmission Electron Microscope

• Reveals its internal structures.

2. Scanning Electron Microscope

• See 3-D images of cell surfaces

• Reveals surface structures.

Image ComparisonCompound Scanning Electron Microscope

Cyclotella 1000X Cyclotella 1000X Transmission EM

VirusesBacteria 10,000XBacteria 1000X

Eyepiece or Ocular Lens

Rotating Nose Piece

Objectives

Stage Clips

Stage

Diaphragm

Light

Base

Fine Adjustment Knob

Coarse Adjustment Knob

Arm

How to Get an Image in Focus

1. Position slide on the stage so the image is centered

2. Turn nosepiece to the lowest objective

3. Turn the coarse adjustment knob to move stage all the way up

4. Turn the knob away until the image is in focus

5. Turn the fine adjustment knob to get a clearer and sharper image

6. Change to the medium objective

7. Only use the fine adjustment knob to bring the image into focus. Do not use the coarse knob.

8. Change to the high objective.

9. Use the fine adjustment knob to bring the image into focus.

• Parfocal – once the image has been brought into focus on low power, the image will remain in focus no matter which objective you use.

• Total Magnification

• The eyepiece has a lens in it that magnifies 10X

• The low power objective magnifies at 4X

• The medium objective magnifies at 10X

• The high objective magnifies at 40X

• To find the total magnification you must multiply the eyepiece and the objective you are on:

• Example: 10 X 4 = 40

10 X 10 = 100

10 X 40 = 400