Scientific Method and Hypothesis Quiz

Chapter 1 Lecture: Learning About Life

• This lecture series is designed for Campbell Essential Biology and Campbell Essential Biology with Physiology, 6th and 7th editions, respectively.
• The materials were created by Edward J. Zalisko, Eric J. Simon, Jean L. Dickey, and Jane B. Reece.
• The content focuses on the scientific study of life, the scientific method, and key biological themes like the relationship of structure to function, information flow, energy/matter transformations, interactions within biological systems, and evolution.

The Scientific Study of Life

• Biology is the scientific study of life.
• Scientific study involves inquiry (searching for information, evidence, explanations, and answers).
• Science differs from other ways of understanding the world by relying on natural causes and verifiable observations/measurements.

An Overview of the Process of Science

• Science seeks natural causes for natural phenomena, using structured inquiry.
• A hypothesis is a proposed explanation for a set of observations; it must be testable and falsifiable.
• Hypotheses can be tested through experiments for easily controlled conditions, or by making observations in uncontrolled situations (like ecological contexts).
• Experiment results either support or reject a hypothesis.

Testing a Common Problem Using the Process of Science

• This section uses the example of a dead remote to illustrate the scientific method.
• Scientific method (in general):
  • Exploration (identifying the problem)
  • Testing (forming hypotheses, predictions, experiments, and conclusions)

Hypotheses, Theories, and Facts

• A scientific theory is a well-substantiated explanation broader than a hypothesis and supported by a large body of evidence.
• Theories are refined or abandoned based on new evidence.

Controlled Experiments

• Researchers often test hypotheses by changing one factor while holding others constant.
• Variables are factors that change during an experiment.
• A controlled experiment compares two or more groups that differ only in the variable the experiment tests.
• The control group doesn't receive the specific factor being tested; the experimental group does.
• Well-designed experiments usually test only one independent variable at a time.
• Independent variable is manipulated, dependent variable responds to change.

Evaluating Scientific Claims

• Assessing the reliability of scientific claims includes scrutinizing the source of the information.
• Peer review is a vital method of evaluating scientific work, where impartial and often anonymous experts assess the work.
• Peer-reviewed journals are the best way to ensure reliability of a publication.
• Evaluating source reliability requires a checklist (is info current? primary/secondary? author well qualified? conflicts of interest? refs? replicable experiments? peer-reviewed? unbiased? known intent?

Major Themes in Biology

• Five unifying themes in biology:
  • structure-function relationship
  • information flow
  • energy/matter transformations
  • interactions in biological systems
  • evolution

The Relationship of Structure to Function

• The structure of a biological component often dictates its function.
• Example: The branched structure of lungs provides a vast surface area for gas exchange.
• Indentations in red blood cells increase their surface area for oxygen diffusion.
• The structure-function relationship is seen at all levels of biological organization.

Information Flow

• For life's functions to proceed in an orderly manner, information must be received, transmitted, and used.
• Information flow is apparent at all levels of biological organization.
• Example: Pancreas releases hormones (like insulin) in response to blood glucose levels.
• Every cell contains genes (hereditary units) of information in DNA sequences passed down from previous generations.

Information Stored in DNA

• (Diagram of DNA structure)

Transformations of Energy and Matter in an Ecosystem

• (Diagram depicting the flow of matter and energy in an ecosystem )

Interactions within Biological Systems

• The study of life spans from molecules to the biosphere (entire living planet).
• Interactions within and between biological systems become more complex at higher levels.
• Emerging properties arise from interactions at these new levels that were not present at previous ones.

Zooming In On Life

• (Diagram of zooming in from biosphere to molecules)

Evolution

• Life is characterized by unity and diversity.
• Multiple lines of evidence (fossil records, common cellular processes, DNA) point to life's unity.
• Evolution, the process of change over time, explains the relationship between life's unity and diversity.
• This change from ancestral species to living species is explained by natural selection.

Evolution (Cont.)

• Evolution is the fundamental principle unifying all of biology.
• Natural selection is the process that explains how organisms adapt to their environments, where individuals with advantageous traits are more likely to survive and reproduce.
• Evolution doesn’t create traits; instead, it selects for pre-existing randomly occurring mutations.

Evolution (Cont.)

• Natural selection acts on pre-existing traits, enhancing survival and reproduction of organisms with beneficial adaptations.

Natural Selection in Action

• (Diagram illustrating natural selection with bacteria and antibiotic resistance)

Evolution Connection: Turtles in the Tree of Life

• Species are connected through a branching tree of life extending back in time.
• Comparing DNA sequences reveals evolutionary relationships.
• Closely related species share a common ancestor more recently than distantly related ones.

A Partial Family Tree of Animals

• (Diagram showing animal relationships)