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The Study of Biology
CHAPTER 1 Biology: Exploring Life
• What Does It Mean to be Alive?
• Levels of Biological Complexity
• The Cellular Nature of Life
• Categorizing Living Things
• Evolution as a Unifying Theme
• Process of Science: The Scientific Method
Eight Properties of Living Things
1) Life is highly ordered and complex in structure.
2) Living things regulate their internal environments (homeostasis).
3) Living things grow by adding on new parts to pre-existing structures
using energy.
4) Living things use energy to maintain order and structure.
5) Living things respond actively to the environment using energy.
6) Living things reproduce by passing on hereditary information to their
offspring.
7) Groups of living things (populations) evolve over several generations.
8) Individual living things are made of one or more cells.
The Study of Biology
CHAPTER 1 Biology: Exploring Life
• What Does It Mean to be Alive?
• Levels of Biological Complexity
• The Cellular Nature of Life
• Categorizing Living Things
• Evolution as a Unifying Theme
• Process of Science: The Scientific Method
African savanna
Increasing complexity
Levels of Biological Organization
Ecosystem (Biome)
Organelle
Mitochondrion
The Study of Biology
CHAPTER 1 Biology: Exploring Life
• What Does It Mean to be Alive?
• Levels of Biological Complexity
• The Cellular Nature of Life
• Categorizing Living Things
• Evolution as a Unifying Theme
• Process of Science: The Scientific Method
Cellular Basis of Life
• Living things are composed
of one of two types of cells
– Prokaryotic
• Simple and tiny
• Example: bacterial cell
– Eukaryotic
• Complex and 10-100
times larger
• Example: cells of a
western hemlock tree
The Study of Biology
CHAPTER 1 Biology: Exploring Life
• What Does It Mean to be Alive?
• Levels of Biological Complexity
• The Cellular Nature of Life
• Categorizing Living Things
• Evolution as a Unifying Theme
•Process of Science: The Scientific Method
How Do Biologists Classify and Catalog Life?
Three Domain System of Classifying Living Things
Domain Eukarya
Bacteria
Eucarya
Soil bacteria
Water bacteria
Disease bacteria
Photosynthetic bacteria
“Extreme” bacteria
that live in high
salt, hot water,
acid, or alkali
(unusual “bacteria”)
All living things
Plants Animals
Fungi Protists
Classification Is Based on a Hierarchy of Groupings or Taxons
Domain
etc.
etc.
etc. etc.etc. etc.etc. etc. etc. etc.etc.etc.
etc. etc. etc.etc. etc. etc. etc.etc.etc.etc. etc.etc.etc.
etc.etc.etc.etc.
The Taxonomic Hierarchy
The Study of Biology
CHAPTER 1 Biology: Exploring Life
• What Does It Mean to be Alive?
• Levels of Biological Complexity
• The Cellular Nature of Life
• Categorizing Living Things
• Evolution as a Unifying Theme
• Process of Science: The Scientific Method
Evolution: Biology’s Unifying Theme
1. In a group of organisms of
the same kind there is:
–
–
Individual variation
Overproduction & competition
2. Different individuals have
different levels of
reproductive success
3. Those individuals with
successful traits pass on their
traits to subsequent generations
4. Groups (populations) of
organisms exhibit descent
with modification
Population with varied inherited traits
Elimination of individuals with certain traits
Reproduction of survivors
Modification: Increased frequency of traits that
enhance survival and reproductive success
The Study of Biology
CHAPTER 1 Biology: Exploring Life
• What Does It Mean to be Alive?
• Levels of Biological Complexity
• The Cellular Nature of Life
• Categorizing Living Things
• Evolution as a Unifying Theme
• Process of Science: The Scientific Method
Four Steps of the Scientific Method
1) Observation
•
Measure the natural world using own
senses or extensions of the senses
(microscopes, detectors, etc.)
Observations
Questions
2) Hypotheses Formation
•
Form tentative, predictive, and testable
statements about two variables that
explain the observations
3) Experimentation
•
Test how one hypothesis variable effects the
other using multiple trials and baseline
experiments (controls)
4) Conclusion
•
Accept or reject the hypotheses based
on experimental data
Hypotheses
Prediction
Test:
experiment or
additional
observations
Form conclusions
The Process of Science: Can Colors Protect a Snake?
Observations and Questions
Questions: Are some snakes colored because it confers a
survival advantage?
Do predators avoid colored snakes because they
learn that they have poisonous bites?
The Process of Science: Hypothesis Formation with Two Variables
• Making tentative, predictive, and testable
statements about snake coloration
Independent variable: set before the experiment begins
– The more brightly colored and distinctive the
pattern on a snake, the less often the snake will be
attacked by predators.
Dependent variable: measured during the course of experimentation
– The less brightly colored and distinctive the
pattern on a snake, the less often it will be attacked
by predators.
Null hypothesis: There is no correlation between variables
– The coloration pattern of a snake has no effect on
the attack frequency of predators.
The Process of Science: Experimentation
Birds allowed to attack different colored artificial snakes
The Process of Science: Experimentation
Controlled variables to
guarantee that only snake
color effected bird attacks
Artificial snakes were all:
• on the same background
• exposed to attack for the
same amount of time
• exposed to attack during
the same time each day
Multiple trials: Experiment repeated
10 times for each snake type to
reduce the chance of collecting
“freak” or unrepresentative data
• made of identical
materials
Process of Science: Theories
• What is a scientific theory, and how is it different
from a hypothesis?
– Theories are widely accepted hypotheses that have
undergone rigorous and repetitive testing by a
large number of scientist
The Study of Biology
CHAPTER 1 Biology: Exploring Life
• What Does It Mean to be Alive?
• Levels of Biological Complexity
• The Cellular Nature of Life
• Categorizing Living Things
• Evolution as a Unifying Theme
• Process of Science: The Scientific Method