1. Lecture 1 Introduction to Biology

2. The Diversity of Life Biology is the study of living things
Living things can be divided into six kingdoms
Protista
Archaea
Bacteria
Animalia
Fungi
Plantae

3. What is Life?
Biology is the study of life - but what does it mean to be alive?
Ludwig von Bertalanffy – life is a system where the whole is greater than the sum of the parts
Modern physiology – life is an electron in search of a resting place
Living organisms and many non-living things share three properties
Complexity
Movement
Response to stimulation

4. Properties of Life All living organisms share five basic properties
Cellular Organization
All living organisms are composed of at least one cell
Metabolism
All living organisms use energy
Homeostasis
All living organisms maintain stable internal conditions
Growth and reproduction
All living organisms grow and reproduce
Heredity
All living organisms possess a genetic system that is based on DNA (Deoxyribonucleic acid)

5. The Organization of Life
Living organisms function and interact with each other at many levels
These levels are organized in a hierarchy of increasing complexity:
Cellular Level
Organismal Level
Population Level 1. 3. 2.

6. Life is an Emergent Property
Each higher level of organization contains novel properties not present at the simpler level of organization
Birth rate & death rate – populations NOT individuals
Evolution – populations evolve biologically NOT individuals
These properties are termed emergent properties
They are a consequence of the structural organization that is the hallmark of life
They characterize many aspects of the living world

7. Five Themes That Unify Biology
Evolution
The gene frequencies change in a species over time
Causes include:
Genetic drift
Natural & artificial selection
Founder effects
The Flow of Energy
All living organisms require energy
The sun is the source of energy for most ecosystems
Plants capture energy via photosynthesis
They then act as an energy source for other organisms
Interaction
Interaction between organisms is critical for evolution
Social behavior occurs when organisms of the same species live in direct contact
Community dynamics occur when organisms of different species live in direct contact (Competition, Predation, Symbiosis)
Structure Determines Function
Biological structures are well suited to their function
This is true at every level of organization
Homeostasis
All living organisms act to maintain a relatively stable internal environment
Maintaining homeostasis requires energy and a lot of signaling back-and-forth between cells

8. How Scientists Think Inductive Reasoning Deductive Reasoning
Is used by scientists to develop hypotheses about how the world works
Deductive Reasoning
Uses accepted general principles as a “guide” to explain specific observations

9. Inference vs. Observation
An observation is limited to a description of actions or events without interpretation
An inference is a conclusion we draw based on what we observe
Inference or observation?
Example 1 (The cat is happy)
Example 2 (The cat is chewing on the plant leaves)
Example 3 (The cat is sleeping)
Example 4 (The cat is a female)

10. Theory and Certainty in Science
A theory is a set of hypotheses that have been tested many times and not rejected
It indicates a high degree of certainty
However, there is no absolute truth in science
So the acceptance of a theory is always provisional
Note:
To the general public, the word theory is often used to mean what a scientist would call a hypothesis, a lack of knowledge or a guess
To scientists, a theory represents that of which they are most certain, explanations supported by a wealth of evidence and experimental data

11. The Limitations of Science
Science is limited to organisms and processes that can be observed and measured
Spiritual and religious phenomena are beyond the scope of science
Most religious explanations do not allow formation of a realistic null hypothesis
There are also practical limits
Science can provide options and understanding
Science cannot be relied upon to solve all problems
For example, what constitutes “acceptable risk” cannot be answered by science!

12. Four Theories Unify Biology & This Class
The Gene Theory
The information that determines what an organism is like is encoded in its genes
Genes are located along DNA molecules
The entire set of DNA instructions that specifies a cell is termed its genome
The Cell Theory
All living organisms are composed of cells
Cells are the basic units of life
All cells come from other cells
The Theory of Heredity
Genes represent traits of an organism and are inherited as discrete units
Chromosomal theory of inheritance: Genes are physically located on chromosomes
The Theory of Evolution
All living organisms are related to one another in a common tree of life
Diversity of the living world is the result of natural selection