BSCI 124 LECTURE NOTES

I. Course introduction: BSCI 124, Plant Biology for Non-science Students

• A. How this course is different from a general botany course? It attempts to be more relevant to non-science majors - stresses:
  • 1. Importance of plants to people
    2. Role of plants in the environment
    3. Environmental problems

  B. Lecture syllabi

  • 1. Lecture schedule
    2. Textbook
    3. World Wide Web Pages
    4. Grading
    5. Information about BSCI 125 (USP/CORE)

II. What is science?

• A. A technique: a way of seeking principles, or order, about the world AND a systematic collection of facts about the natural world
  • 1. Other fields do the same thing in different ways- art, philosophy, religion
    2. Science is different because it tries to VERIFY these principles
    • a. Scientific proposals must be testable

  B. Scientists collect evidence, or data (plural; datum, singular)

  • 1. The facts with which science works are called data
    2. Data must be objective with exclusion of emotion and bias as much as possible
    3. Data are collected in experiments by observation and measurement
    4. Data interpretation (called data analysis) allows us to see new relationships, which leads to the development of new ideas
    5. Scientific conclusions are based on available data.

  C. Scientists use the scientific method:(click here for another explanation too) a method of research in which a problem is identified, relevant data are gathered, a hypothesis is formulated from these data, and the hypothesis is experimentally tested.

  • 1. Hypothesis - an educated statement that is testable
    2. Theory - a hypothesis that has survived many independent tests and any competing hypotheses have been disproved
    3. Principle or law - a theory that has withstood repeated testing; based on a large database in which no datum is in disagreement

  D. Scientists cannot claim a final or permanent truth

  • 1. Science evolves, or changes; science is a process - what our students learned as fact 5 years ago is not necessarily fact today
    2. Newly discovered, verifiable facts ALWAYS take precedence.  e.g. Spontaneous generation disproved

PART 1: WHAT IS LIFE? I. Plants (and living organisms in general) exhibit great variety

• A. Size: microorganisms ---> giant sequoias
  B. Shape: filaments of algae (threads several inches long) ---> barrel cacti
  C. Variable habitats: Antarctic ---> deserts ---> ocean depths

II. All living things share certain characteristics

• A. Highly organized
  • 1. Atoms ---> molecules ---> macromolecules ---> organelles ---> cells ---> tissues ---> organs ---> (organ systems) ---> organisms ---> populations ---> communities ---> biosphere (ecosphere)
    2. Composed of cells
    • a. Basic unit of life
      b. The lowest level of organization that can perform all the activities of life
      c. Life has been on the earth for some 3.5 billion years

    3. Plant organelles differ slightly from those of animals -- see this diagram

  B. Maintain a stable and characteristic chemical composition

  • 1. The same chemicals are associated with all life: proteins, carbohydrates, lipids, nucleic acids (also salts and water)
    2. Same in pines, grasshoppers, and humans

  C. Take in energy from environment, transform it and use it

  • 1. Living things need energy for their activities (growth, movement, repair and maintenance); like a car, living things tend to break down
    2. Metabolism- all the chemical reactions that take place in a cell or organism; require energy
    3. ATP- small, energy-carrying molecule common to all cells

  D. Respond to stimuli

  • 1. Algae swim toward light
    2. Plant roots grow in direction of gravity
    3. Different organisms may respond to same stimulus differently (kick a tree and kick a bear; long day and short day plants)

  E. Grow and develop

  • 1. Food utilized -> chemical building blocks that are reassembled
    2. Nonliving "growth" is the addition of materials to outside without a change in material (example- stalactites and stalagmites)

  F. Reproduce

  • 1. Needed because all living things eventually die; some live a long time (bristlecone pine), but all eventually die
    2. Sexual versus asexual reproduction (sexual gives important biological value beyond producing more offspring; gives genetic variety)

  G. Show variations based on heredity

  • 1. Possess genes composed of DNA
    2. Order of nucleotides (the building blocks of DNA) is a code that determines everything about the organism

  H. Adapted to their environments and ways of life

  • 1. Show adaptation- any variation in structure, life processes, or behavior that promotes the likelihood of an organism surviving and reproducing in a particular environment
    2. Example- cactus stem and leaves (spines) are adaptations
    3. Evolution- progressive adaptations of organisms to their environments

  Links to other sites

  Biographies of people critical in the development of science

  • Aristotle
  • DaVinci
  • Hooke
  • Leeuwenhoek

  History of Science: Medieval Science
  Bioethics
  Scientific investigation
  Origin of Life
  Events over geologic time

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Last revised: August 11, 1998