Exploring Life and Science

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Chapter 1

• Exploring Life and Science

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What characteristics are shared by living
organisms?

1. Organized from the atom to the biosphere
2. Maintain a relatively constant internal
   environment (homeostasis)
3. Respond to internal and external stimuli
4. Use materials and energy from the environment
5. Reproduce offspring
6. Growth and development
7. Evolutionary history through which organisms
   change over time

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How are living things organized? From Simple to
Complex

• Atoms
• are the smallest chemical units
• Molecules
• are a group of atoms working together
• Organelles
• are a group of molecules working together
• Cells
• are a group of organelles working together
• Tissues
• are a group of similar cells working together

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How are living things organized? From Simple to
Complex

• Organs
• are a group of different tissues working together
• Organ systems
• are a group of organs working together
• Organism
• is an individual

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How are living things organized? From Simple to
Complex

• Population
• Organisms of the same species in a particular
  area
• Community
• Interaction populations in a particular area
• Ecosystem
• A community plus the physical environment
• Biosphere
• Regions of the Earths crust, waters, and
  atmosphere inhabited by living things

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Reproducing and Growth Development

• DNA
• Hereditary information directs
• Structure of the Cell
• Cell Metabolism
• Genes
• Allow cells and organisms to make more of
  themselves
• Direct development so that the organism resembles
  the parents
• Growth and Development
• Growth increase in size and number of cells
• Development
• All changes that occur from birth to death
• Repair after an injury

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Homeostasis

• Homeostasis
• All body systems working together to maintain a
  stable internal environment
• Systems respond to external and internal changes
  to function within a normal range
• e.g. body temperature, fluid balance
• Failure to function within a normal range results
  in disease

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Maintaining Normal Limits

• Receptor
• receives the stimulus
• Control center
• processes the signal and sends instructions
• Effector
• carries out instructions

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Maintaining Normal Limits
Figure 13
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Negative Feedback

• The response of the effector negates the stimulus

Figure 14
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Positive Feedback

• The response of the effector reinforces the
  stimulus

Figure 15
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Homeostasis

• Requires coordinated efforts of multiple organ
  systems. Any adjustment made by one
  physiological system has direct and indirect
  effects on a variety of other systems.
  Therefore, the use of homeostasis integrates the
  human body to allow for the support of life.

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Evolution and Adaptation

• Evolution
• Process by which a species changes through time
• New variations arise allowing species to capture
  more resources ? them to survive
• Each successive generation include this variation
  representing an adaptation to the environment

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How are living organisms classified?

• Three Domains
• Eukarya, Archaea, and Bacteria
• Eukarya Kingdoms
• Vertebrate
• Animalia
• Invertebrate
• Plantae, Fungi, and Protista
• Archaea Kingdom
• Archaea
• Bacteria Kingdom
• Eubacteria

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How do we classify humans?
Human House Cat
Domain Eukarya Eukarya
Kingdom Animalia Animalia
Phylum Chordata Chordata
Class Mammalia Mammalia
Order Primates Carnivora
Family Hominidae Felidae
Genus Homo Felis
Species sapiens domesticus
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What distinguishes humans?

1. Cultural heritage or patterns of our behavior
   passed from one generation to the next
2. Well-developed brains
3. Upright stance
4. Language Skills
5. Varied Tool Use
6. Modification of our environment for our own
   purpose which may threaten the biosphere

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What do we know about Science?

1. Science is a way of knowing about the natural
   world
2. Science and scientists should be objective
3. Scientific conclusions may change or be modified
   as our understanding and technology increases
4. Science is studied using the scientific method

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Science as a Process

• Scientific Theory
• Tells us about the order and the patterns in the
  world
• Examples
• Cell, Homeostasis, Genes, Evolution
• Principle
• Theories that are accepted as valid by an
  overwhelming number of scientists

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The Steps of the Scientific Method
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The Scientific Method in Action

• Observations
• - Many patients had a particular bacterium near
  their ulcers
• Hypothesis
• - Heliobacter pylori is the cause of gastritis
  and ulcers
• Experimental/observations
• 1st H. pylori was isolated and grown from ulcer
  patients
• 2nd Humans swallowing a H. pylori solution
  resulted in inflammation in their stomachs
• Conclusion
• - H. pylori was the cause of most ulcers and can
  be cured by antibiotics

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A Controlled Study

• Variables
• Experimental variable is the variable that is
  purposely changed or manipulated
• All other variables need to remain constant
• Groups
• Test group is a group of subjects that are
  exposed to the experimental variable
• Control group is a group for comparison that is
  not exposed to the experimental variable

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Reading about scientific information

• Scientific journals are considered the best
  source of information but can be difficult for
  the lay person to understand
• Often the lay person reads secondary sources and
  must be wary of information taken out of context
• Be careful of information on the Internet by
  using reliable sources such as URLs with .edu,
  .gov and .org

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What should you look for when you read about
science?

• Beware of anecdotal data
• Understand methodology and results
• Does the data justify the conclusions inferred by
  the scientists?
• Be able to read a graph
• Have some understanding of statistics
• Standard Error (example 5 1)
• Statistical Significance (Plt 0.5)
• Possibility that the results are due to some
  other factor other than the experimental variable

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Does science have social responsibilities?

• Science is a way of acquiring knowledge about the
  natural world through a systematic process
  separating it from ethics, religion and
  aesthetics
• Technology is the application of scientific
  knowledge to human interests
• Biotechnology (genetically modified crops)
• Gene technology (cloning of humans or gene
  therapy to modify inheritance)
• Use of stem cells from embryos