Biology Chapter 1: Exploring Life

Chapter 1: Biology - Exploring Life

• Biology is the scientific study of life.
• Properties of life include:
  • Order - highly organized structures
  • Reproduction - ability to reproduce their kind
  • Growth and development - consistent growth and development directed by DNA
  • Energy processing - using chemical energy for activities and chemical reactions
  • Response to the environment - ability to respond to environmental stimuli
  • Regulation - maintaining internal environment within limits
  • Evolutionary adaptation - adaptations that evolve leading to greater reproductive success

Themes in the Study of Biology

• Biological organization, from smallest to largest:
  • Biosphere - all environments on Earth
  • Ecosystem - organisms and their physical environment
  • Community - all organisms in an area
  • Population - all individuals of a particular species
  • Organism - individual living thing
  • Organ system - several organs working together
  • Organ - structure made of tissues performing a function
  • Tissue - group of similar cells
  • Cell - fundamental unit of life
  • Organelle - membrane-bound structure performing specific functions
  • Molecule - cluster of atoms
  • Atom - smallest unit of a chemical element

Emergent Properties

• New properties arise in each step of the hierarchy of life, arising from the arrangement and interactions within the components.

Cells

• Cells are the structural and functional unit of life. All cells:
  • Are enclosed by a membrane that regulates passage of materials.
  • Use DNA as genetic information.
• Two basic types:
  • Prokaryotic cells - simpler, smaller, were the first to evolve
  • Eukaryotic cells - contain membrane-enclosed organelles and DNA; found in plants, animals, fungi, and many protists.

Living Organisms and Environments

• Living organisms interact with their environment exchanging matter and energy.
• In most ecosystems:
  • Plants are producers, providing food.
  • Consumers eat plants and other animals.
  • Decomposers recycle elements, changing complex matter into simpler mineral nutrients (e.g., in soil).
• Dynamics of ecosystems include two processes:
  • Recycling chemical nutrients (atmosphere and soil) through producers, consumers, and decomposers
  • One-way flow of energy (enters as sunlight, converted to chemical energy by producers, passed to consumers, and exits as heat).

Evolution

• Evolution explains the unity and diversity of life encompassing billions of years and evolving life forms.
• In 1859, Charles Darwin published "On the Origin of Species by Means of Natural Selection":
  • A large amount of evidence supports the idea of evolution; descendants of ancestral species changing over time.
  • Natural selection is a mechanism of evolution. Individuals better suited to their environment have a higher chance to survive and reproduce passing beneficial traits to the next several generations. This drives evolutionary adaptation.

The Scientific Method

• Observation - noticing specific features.
• Hypothesis - proposed explanation for an observation. A good hypothesis is both testable and falsifiable.
• Prediction - specific results expected if the hypothesis is true.
• Experiment - designed to test the prediction.
• Test outcome and conclusion - decide if hypothesis is supported, revised or discarded.
• Variables:
  • Independent variable - the factor deliberately changed by the scientist.
  • Dependent variable - the factor being measured as a result of the change.
  • Controlled variables - factors that remain constant.
• Control - subject not exposed to the treatment.

Research Project Example

• Observing/generalizing about species mimicry.
• Testing the hypothesis using a controlled experiment (experimental group vs. control) with data that supports or refutes the hypothesis.