The Science of Biology

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Chapter 1

• The Science of Biology

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What is Science?

• Science -an organized way of using evidence to
  learn about the natural world.
• Goals of science
• Investigate understand the natural world.
• Explain events in the natural world.
• Make predictions.

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• Why science works
• Only deals w/ the natural world.
• Scientists collect organize info in a careful,
  orderly way.
• Scientists look for patterns connections b/t
  events.
• Scientists explanations can be tested!

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Thinking Like a Scientist

• To think like a scientist you must do a few
  things
• Observe
• Collect data
• Make an inference

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• Observations use senses to get info.
• Info is called data.
• Data can be quantitative or qualitative.
• Quantitative -counted or measured.
• Example there are 12 inches in a foot.
• Qualitative -cant be counted.
• Example the scar on a manatee looks old

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• Once scientists have data, they make inferences.
• Inference a logical interpretation based on
  prior knowledge or experience.
• Example
• You observe smoke coming from a building.
• You infer that where there is smoke there is
  fire.

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Explaining Interpreting Evidence

• Example
• Many people contract an unknown disease after
  attending a public concert.
• Public health officials will likely use the
  scientific method to try solve why this
  happened.

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• After making observations scientists will propose
  1 or more hypothesis.
• Hypothesis a proposed scientific explanation for
  a set of observations.
• It uses prior knowledge
• Logical inferences
• A creative imagination

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• Possible hypothesis could be that
• The disease spread from person to person via
  contact.
• It spread by insect bites.
• Or, it spread through air, food, or water.

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• A hypothesis must be able to be tested.
• Hypothesis can be tested by
• Controlled experiments
• or
• Gathering more data

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Science as a way of Knowing

• Science is always changing.
• New tools, techniques, discoveries lead to new
  understandings.
• Good scientists are skeptics
• You question everything?
• You must be open minded.
• Be open to new ideas hypothesis.

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Science Human Values

• Science is in many of the questions of today.
• How should chemical wastes be disposed of?
• Who should be responsible for their disposal?
• Should our electricity come from nuclear or
  hydroelectric?
• Should the info in your genes be kept private?

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• All of these question involve science in a way.
• But, science cant answer them.
• Science makes recommendations.
• Society has the final decision.
• We consider our laws moral principles, then we
  make a decision.

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Section 2

• How Scientists Work

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Designing an Experiment

• Some old ideas about living things
• P. 8
• Fig. 1.7

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Required Steps in a Good Experiment

• Ask a question
• How, why?
• Forming a Hypothesis
• Years ago people thought living things came from
  nonliving things.
• This idea was called spontaneous generation.

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• Ex
• mice spontaneously appear in stored grain
• maggots spontaneously appear in meat.
• Spontaneous generation was a hypothesis.
• Remember!
• Hypotheses must be tested.
• The idea that maggots came from meat was tested
  by Francesco Redi.
• To test it, Redi needed an experiment.
• So, he devised a controlled exp.

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• Setting Up a Controlled Experiment
• Factors that can be changed in an exp. are called
  variables.
• Examples
• Equipment used
• Type of materials
• Amount of materials
• Temp.
• Light
• Time

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• Hypotheses are tested in an experiments. where
  only 1 variable is changed at a time.
• This is called a controlled exp.
• Controlled exp. have 2 types of variables
• Manipulated variable
• Variable that is deliberately changed.
• Responding variable
• Variable changes in response to the manipulating
  variable.
• Refer to Redis Exp. Fig. 1-8

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OBSERVATIONS Flies land on meat that is left
uncovered. Later, maggots appear on the meat.
HYPOTHESIS Flies produce maggots.
PROCEDURE
Uncovered jars
Covered jars
Controlled Variables jars, type of
meat, location, temperature, time
Manipulated Variables gauze covering that keeps
flies away from meat
Several days pass
Responding Variable whether maggots appear
Maggots appear
No maggots appear
CONCLUSION Maggots form only when flies come in
contact with meat. Spontaneous generation of
maggots did not occur.
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• Recording Analyzing Results
• Scientists keep records of their observations,
  experements, or data.
• These records are kept in
• Journals
• Notebooks
• Drawings Fig. 1-8
• Computers
• Did Redi keep records?
• Yes

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• Drawing Conclusions
• Evidence from a exp. either supports or disproves
  a hypothesis.
• Did Redis exp. support his hypothesis?
• Yes, it disproved the theory of spontaneous
  generation.

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Repeating Investigations

• Often, scientists place their procedures
  findings of an experiments in scientific
  journals.
• They do this so other scientists can repeat their
  work.
• Why?
• Scientists can confirm or deny other scientists
  findings.

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Designing an Experiment
State the Problem
Analyze Results
Form a Hypothesis
Draw a Conclusion
Set Up a Controlled Experiment
Publish Results
Record Results
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• Lets look at some scientists who questioned
  Redis findings
• P. 11-13
• Needham fig. 1-10
• Spallanzani fig. 1-10
• Pasteur fig. 1-11

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Needhams ExperimentFig. 1-10Spallanzanis
Experimentfig. 1-10
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Pasteur's Experiment fig. 1-11
Broth is boiled.
Broth is free of microorganisms for a year.
Curved neck is removed.
Broth is teeming with microorganisms.
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When Experiments Are Not Possible

• You cant always do an exp. to test a hypothesis.
• When this happens you can do
• Field studies more observations
• Enables us to study animal behavior
• Fig 1-12
• Medical studies testing
• Usually on volunteers

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How a Theory Develops

• Theory -A very well tested explanation that
  unifies a broad range of observations.
• Examples of theories
• Theory of Biogenesis
• All living things come from other living things.
• Verified by Pasteur
• Theory of Evolution
• The Cell Theory
• Big Bang theory

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• Some explanations in life need more than one
  theory.
• Fig. 1-13
• Examples
• Theory of Evolution
• Cell Theory
• Theory of Plate Tectonics

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Section 3

• Studying Life

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• What is biology?
• study of life
• Biology understanding the living world.

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Characteristics of Living Things

• All living things share these characteristics
• made of cells
• reproduce
• a genetic code (DNA)
• grow develop
• use materials energy
• respond to their environment
• maintain their internal env. (homeostasis)
• evolve
• Fig. 1-14

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• Made up of cells
• Cell a collection of living matter enclosed by a
  barrier that separates it from its surroundings.
• Cell -the smallest unit of life.
• Cells -complex highly organized.

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• Orgs. can be unicellular or multicellular.
• Unicellular single celled
• Ex bacteria
• Multicellular many celled
• Ex humans
• Fig. 1-15

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• Reproduction
• There are 2 types of reproduction
• Asexual
• A before a word means w/out.
• The new org. has a single parent.
• Offspring are exact duplicates of the parent.
  (clones)
• Fig. 1-16 shows budding of a hydra.
• Sexual
• Cells from 2 different parents unite to make the
  1st cell of the org.

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• Based on Genetic Code
• Offspring resemble their parents.
• All living orgs. have DNA.
• DNA Deoxyribonucleic Acid
• Determines the traits of every org. on Earth.

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• Growth Development
• All living things grow to some extent.
• Growth increase in size.
• However, multicellular orgs. go through
  development.
• Development involves cells dividing becoming
  specialized or differentiated.
• Ex Stem cells can become
• nerve cells
• skin cells
• liver cells
• brain cells
• Fig. 1-17

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• Need for Materials Energy
• Metabolism set of chem. reactions through which
  an org. builds up/breaks down materials.
• All orgs. need energy (E).
• Plants, some bacteria, most algae get E from
  the sun.
• Animals get E from food.

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• Response to the Env
• All orgs. sense respond to stimuli in their
  env.
• Stimulus a signal to which an org. responds.
• Ex plant seeds respond to warmth water.

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• Maintaining Internal Balance
• Homeostasis process by which orgs. maintain a
  relatively stable internal env.
• Ex home heating/cooling system.
• Another example, the bird in fig. 1-19.
• When it is cold it hunches down adjusts its
  feathers for maximum insulation.

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• Evolution
• Evolution process by which modern orgs. have
  descended from ancient orgs. over long periods of
  time.

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Characteristics of Living Things
Characteristic
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. Seeds
from maple trees produce maple trees.
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.
Leaves and stems of plants grow toward light.
Living things respond to their environment.
Despite changes in the temperature of the
environment, a robin maintains a constant body
temperature.
Living things maintain a stable internal
environment.
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.
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Branches of Biology

• Some branches of biology
• Zoology study animals
• Botany-study plants
• Paleontology-study of ancient life
• Molecular/Cell biologists- study of the smallest
  life forms.
• Population biologists ecologists study of the
  largest systems on Earth.

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Organism
Individual living thing
Bison
Tissues, organs, and organ systems
Groups of Cells
Nervous system
Brain
Nervous tissue
Smallest functional unit of life
Cells
Nerve cell
Groups of atoms smallest unit of most
chemical compounds
Molecules
DNA
Water
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Biosphere
The part of Earth that contains all ecosystems
Biosphere
Ecosystem
Community and its nonliving surroundings
Hawk, snake, bison, prairie dog, grass, stream,
rocks, air
Community
Populations that live together in a defined area
Hawk, snake, bison, prairie dog, grass
Population
Group of organisms of one type that live in the
same area
Bison herd
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Section 4

• Tools Procedures

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A Common Measurement System

• Scientists use the metric system for data
  performing experiments.
• Metric system
• -a decimal system of measurements w/ units that
  are based on multiples of 10.
• International System of Unitsrevised version of
  the metric system.
• Abbreviated as SI
• Les Systeme International dunites (French)

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Common Metric Units Common Metric Units
Length Mass
1 meter (m) 100 centimeters (cm) 1 meter 1000 millimeters (mm) 1000 meters 1 kilometer (km) 1 kilogram (kg) 1000 grams (g) 1 gram 1000 milligrams (mg) 1000 kilograms 1 metric ton (t)
Volume Temperature
1 liter (L) 1000 milliliters (mL) 1 liter 1000 centimeters (cm3) 0 ºC freezing point of water 100 ºC boiling point of water
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Analyzing Biological Data

• Once scientists collect data, they put it in
  tables graphs.
• Graphs make it easier to analyze data.

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Fig. 1-24, p. 25

• Water Released Absorbed by Tree

Water Released and Absorbed by Tree
Absorbed by Roots (g/h)
Released by Leaves (g/h)
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Water released by leaves
Time
15
8 AM
2
1
10
Relative Rates (g/h)
10 AM
5
1
12
12 PM
4
5
2 PM
6
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Water absorbed by roots
4 PM
9
16
0
6 PM
14
10
8 AM
10 AM
12 PM
2 PM
4 PM
6 PM
8 PM
8 PM
10
3
Time
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• Today, computers help analyze data.
• Examples
• They help determine structure of molecules.
• They enable us to look through a DNA molecule.
• Computers gather satellite data.
• Global climate changes

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Microscopes

• Microscope -device that magnifies images of
  structures.
• There are 2 main types of microscopes
• Light microscope
• Electron microscope

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• Light Microscopes
• Most common
• Can magnify up to 1000x.
• Compound light microscopes uses light to pass
  through the specimen uses 2 lenses to form an
  image.
• We use the light microscope to
• Study dead orgs. their parts.
• Observe tiny orgs. cells while alive.

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• Electron Microscopes
• When scientists look at even smaller objects they
  rely on Electron Microscopes (EM).
• Electron microscopes use a beam of electrons,
  rather than light, to produce images.
• The best EM can make images 1000x more detailed
  than a light microscope.

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• There are 2 types of EM
• Transmission EM (TEM)
• Scanning EM (SEM)
• The TEM produces images that are a cross section
  of an object.
• The SEM produces 3D images of an object.
• There is a negative to the use of EMs.
• You cannot view living things.

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TEM
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SEM
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Lab Techniques

• Biologists use many ways to study cells.
• 2 common ways are
• Cell cultures
• Cell fractionation

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• Cell cultures
• A group of cells grown in a nutrient solution
  from a single original cell.
• Cell cultures are used for
• Testing cell responses under controlled
  conditions.
• Studying the interactions b/t cells.
• Selecting specific cells for further study.

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• Cell fractionation
• The technique in which cells are broken into
  pieces the different cell parts are separated.

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Working Safely in Biology

• Always follow safety rules.
• Wash hands after every scientific activity.
• Always wear protective gear when called for.