The Science of Biology

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The Science of Biology

• What is Science?
• The Scientific Method
• Tools Used in Science
• What is Biology?

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What is Science?

• An organized way of using evidence to learn about
  the natural world
• Body of knowledge that scientists have built up

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Steps used in science

• Observation using one or more of the senses to
  gather information
• Inference a logical interpretation based on
  prior knowledge and experience

• Data information gathered from observations
• Quantitative involve numbers
• Qualitative involve characteristics that cannot
  be easily measured or counted, such as color or
  texture

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Observation vs. Inference
Statement Observation Inference
X
Object A is round and orange.
X
Object A is a basketball.
X
Object C is round and black and white.
X
Object C is larger than Object B.
X
Object B is smooth.
X
Object B is a table-tennis ball.
X
X
Each object is used in a different sport.
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Scientific Method

• 1. Stating the Problem based on observations,
  identify a problem to be solved

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Scientific Method cont.

• 2. Forming a Hypothesis a possible explanation
  for a set of observations or an answer to a
  scientific question
• Prior knowledge
• Logical inferences
• Imaginative guesses

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Scientific Method cont.

• 3. Setting up a Controlled Experiment an
  experiment in which only one variable is changed
  at a time
• Manipulated variable (independent) the variable
  that is changed by the scientist
• Responding variable (dependent) the variable
  that changes in response to the manipulated
  variable
• If an experiment cannot be done, field studies
  will be done

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Spontaneous Generation Experiment
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
Several days pass
Manipulated Variables gauze covering that keeps
flies away from meat
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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Another Spontaneous Generation Experiment
Gravy is boiled.
Flask is open.
Gravy is teeming with microorganisms.
Flask is sealed.
Gravy is free of microorganisms.
Gravy is boiled.
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Another Spontaneous Generation Experiment
Broth is boiled.
Broth is free of microorganisms for a year.
Curved neck is removed.
Broth is teeming with microorganisms.
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Scientific Method cont.

• 4. Record and Analyze Results keep written
  records of observations or data
• Notebooks, journals, drawings, computer

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Scientific Method cont.

• 5. Drawing a Conclusion determine whether the
  hypothesis is supported or refuted

Yes
No
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Then what?

• Publish study in a scientific journal
• Other scientists review the procedures and may
  perform their own experiments to verify the
  results
• If the hypothesis is continually supported it may
  become a theory
• No theory is considered absolute truth!!!!!

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Tools used in Science

• Microscopes
• Three kinds compound light microscope,
  transmission electron microscope, and scanning
  electron microscope
• Magnification determined by multiplying the
  eyepiece times the objective
• Resolution ability to distinguish between two
  objects

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Compound Light Microscope

• Light passes through the object
• Magnification up to 1000 times
• Resolution up to 500 nanometers

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Compound Light Microscope
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Compound Light Microscope
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Transmission Electron Microscope (TEM)

• Passes a beam of electrons through the object
• Focused by magnets
• Only dead cells can be viewed
• Cells must be embedded in plastic and sliced thin
• Much greater magnification resolution (.2nm)

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Transmission Electron Microscope
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Scanning Electron Microscope (SEM)

• Beam of electrons sweeps over and bounces off of
  object
• Produces a 3-D image
• Less magnification than TEM
• Possible for living cells

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Scanning Electron Microscope
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Metric System or System Internationale (SI)

• Reasons scientists use the metric system
• Based on the number 10
• Easy to convert
• Universally understood

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Metric Units

• Length meter (m)
• Mass gram (g)
• Volume (liquid) liter (L)
• Time second (s)
• Temperature Celsius (C) or Kelvin (K)

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Metric Prefixes
Deca da 10
Hecto h 100
Kilo k 1000
Deci d 1/10
Centi c 1/100
Milli m 1/1000
Nano n 1/billionth
Micro ? 1/millionth
METER GRAM LITER SECOND
King Henry Died By Drinking Chocolate Milk Monday
Night
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What is Biology?

• Bios life or living things
• -ology study of
• Study of life or living things

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Characteristics of Living Things

• Living things are made of cells
• Cells are the smallest units of an organism that
  can be considered alive
• Unicellular one-celled
• Multicellular many-celled

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Characteristics of Living Things

• Living things reproduce
• Production of new organisms

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Characteristics of Living Things

• Living things are based on a universal genetic
  code (DNA)

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Characteristics of Living Things

• Living things grow and develop
• Growth an increase in size
• Development changes that occur as an organism
  grows

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Characteristics of Living Things

• Living things obtain and use materials and energy
• Producers make their own food
• Consumers eat other living things

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Characteristics of Living Things

• Living things respond to their environment
• Temperature
• Ex. Birds fly south for the winter
• Light
• Ex. Plants grow towards the sunlight if placed in
  a window

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Characteristics of Living Things

• Living things maintain a stable internal
  environment
• Homeostasis keep internal conditions relatively
  stable
• What does your body do when you are cold?
• shivers
• What does your body do when you are hot?
• sweats

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Characteristics of Living Things

• As a group, living things change over time
• Evolution change over time
• Ex. The brain cavity of human skulls is larger,
  our jaws are smaller, on average we are taller

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Characteristics of Living Things

• Living things
• Are made of cells
• Reproduce
• Are based on a universal genetic code
• Grow and develop
• Obtain and use materials and energy
• Respond to their environment
• Maintain a stable internal environment
• Change over time

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Levels of Organization

• Molecules-chemical components which are the
  building blocks of organelles
• Organelles-perform certain organ-like tasks
  within cells.
• Cell-smallest unit of life
• Tissue-group of specialized cells
• Organ-all tissues which work together as one
• Organ System-all organs which perform common
  functions

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Levels of Organization

• Organism an individual living thing
• A cow
• Population group of organisms
• A herd of cows
• Community populations that live together
• A herd of cows, the grass, and flies
• Ecosystem community non-living factors
• The cows, grass, flies, rocks, and streams
• Biosphere contains all ecosystems
• The entire Earth