The Nature of Biology

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The Nature of Biology

• Module 1 How to Define Life

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How do you design an experiment?

• A. Problem/Purpose
• The question the lab will answer
• Identifies the independent and dependent
  variables
• Independent variable the factor the scientist
  changes from group to group
• Dependent variable the factor the scientist
  measures to see the effect of the independent
  variable
• Variables and Controls Videoclip

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How do you design an experiment?

• B. Research/Background Information
• Lets the reader learn about the topic
• Helps the scientist develop an educated
  hypothesis
• C. Hypothesis
• An educated prediction
• Can be tested, proven false, and agrees with
  previous research

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How do you design an experiment?

• D. Procedure/Experiment
• Steps must be precise and detailed
• Has one control group
• Normal conditions or absence of independent
  variable
• Used for comparison
• Experimental group(s) have only one changing
  variable (which is the independent variable)

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How do you design an experiment?

• E. Observations/Data
• Must be objective.
• Good Example The bacterial colony is yellow.
• Bad Example The bacterial colony is nasty.
• Use measurements whenever possible.
• Good Example There are 50 bacterial colonies.
• Bad Example There are a whole bunch of colonies.

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How do you design an experiment?

• E. Observations/Data
• Do not draw conclusions in the data section of
  the report.
• Good Example There are bacteria and fungal
  colonies in the shoe section.
• Bad Example The shoe was really dirty and so it
  was the most contaminated and grew a lot of
  stuff.
• Should be organized.
• May use a graph, table, or drawing(s).
• Always include units of measurement and a title.

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How do you design an experiment?

• F. Analysis/Conclusions
• Answers the purpose question.
• Accepts or rejects the hypothesis.
• Explains what can be inferred from the data.

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How do we know it is good science?

• A. Scientific knowledge must be shared, which
  allows other scientists to repeat and verify the
  work of others (peer review).
• A. Scientific knowledge is tentative.
• Theories are the most logical explanation based
  on current evidence, become stronger as more
  evidence is gathered, and give us a basis for
  prediction.
• Laws are universal generalizations that are
  virtually unchanging.

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How do you know something is alive?

• A. Biology means the study of (-ology) all life
  (bio-) and includes many branches.
• B. Biologists organize living things into
  kingdoms. There are currently six kingdoms

Kingdom Example
Archaebacteria Extremophile bacteria
Eubacteria Typical bacteria
Protista Seaweed, Amoeba, Slime Mold
Fungi Yeast, Mushrooms
Plantae Moss, Fern, Holly, Oak tree
Animalia , Fish, Birds, Frogs, Humans
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How do you know something is alive?

• Characteristics of Life - Alive! Videoclip
• 1. Organization (The level of complexity)
• a.

Organism
Organ System
Organs
Tissues
Cells
Molecules
Atoms / Elements Meet the Elements - They
Might Be Giants
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How do you know something is alive?

1. All living things need six essential elements
   (atoms) Carbon, Hydrogen, Nitrogen, Oxygen,
   Phosphorus, Sulfur (CHNOPS)
2. All living things are made of cells.
3. One-celled organism unicellular
4. Many-celled organism - multicellular

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How do you know something is alive?

• 2. Energy Use
• a. Organisms need energy constantly to build
  molecules (synthesis) and cells and to break down
  (digest) substances (such as breaking down food
  for nutrition)
• b. Organisms must transport nutrients to be used
  in cellular respiration to produce energy.
• c. An organisms chemical reactions are called
  its metabolism

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How do you know something is alive?

• 3. Reproduction
• a. Organisms must replace themselves so the
  entire species will survive.
• b. May be asexual (only one individual
  contributes genetic material) or sexual (two
  individuals contribute genes).

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How do you know something is alive?

• 4. Growth and Development
• a. Growth to increase in size. Increases the
  number of cells of a multicellular organism.
• b. Development change that takes place in
  structure and function of an organism during its
  life cycle.
• Example Embryo becomes a fetus

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How do you know something is alive?

• 5. Respond to Stimuli
• a. A quick, non-permanent change
• b. Stimulus any condition that causes an
  organism to react.
• Example A loud noise (stimulus) causes your dog
  to run under the bed (response).

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How do you know something is alive?

• Adjust to Environment
• a.Homeostasis - the regulation of an
  organisms internal environment to maintain
  conditions suitable for life
• Ex Getting rid of wastes by excretion

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How do you know something is alive?

• b. An adaptation is an inherited structure,
  behavior, or internal process that enables
  organisms to better survive an environment.
• Ex Gills on a fish

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Life Processes STERNGRR

• Synthesis making materials
• Transport moving materials
• Excretion getting rid of wastes
• Respiration gas exchange AND production of
  energy (ATP)
• Nutrition gaining and using energy from food
• Growth and Development getting bigger and/or
  changing
• Regulation controlling internal processes
• Reproduction producing new cells or new
  organisms

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What technology allows biologists to study
microscopic life?

• A. Compound Light Microscope
• Has two lenses ocular (eyepiece) and objective
• In order to be viewed, specimen must be thin (so
  the light may shine through the specimen) and
  placed on a slide.
• Specimen may be stained to better see structures

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What technology allows biologists to study
microscopic life?

• B. Electron Microscope
• Uses electrons to produce an image
• Types
• Scanning Electron Microscope (SEM)
• Sends a beam of electrons across the objects
  surface
• Produces a 3-D image
• Transmission Electron Microscope (TEM)
• Designed to look at structures inside a cell
• Capable of greatest magnification

Eye of an ant
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What technology allows biologists to study
microscopic life?

• C. Limitations of microscopes
• Magnification is limited by the strength of the
  lens.
• Calculating magnification
• Ocular lens x objective lens total
  magnification
• Example
• Ocular (10x) x objective (40x) 400x
• As magnification increases resolution/(sharpness)
  decreases.