THE SCOPE OF BIOLOGY Chapter 1 Life’s levels of...
Transcript of THE SCOPE OF BIOLOGY Chapter 1 Life’s levels of...
Birgit Woelker, PhD
Chapter 1
Biology: Exploring Life
THE SCOPE OF BIOLOGY Life’s levels of organization define the scope of biology
1. Biosphere
2. Ecosystem
3. Community
4. Population
5. Organism
6. Organ system
7. Organ
8. Tissue
9. Cell
10. Organelle
11. Molecule Atom
Nucleus
Brain
Spinal cord
Nerve
1 2
3 4
6 5
7 8
9 10
11
Living organisms and their environments form interconnecting webs
• Ecosystems are characterized by the cycling of chemical nutrients from the atmosphere and soil
– To producers to consumers to decomposers and back to the environment
• Energy flows one-way through an ecosystem
– From the sun to producers to consumers and exits as heat
Sun
Air
CO2
O2 CO2
H2O
Chemical energy
Inflow of
light energy
Loss of
heat energy
Producers
Cycling of
Chemical nutrients Consumers
Decomposers
Soil
Ecosystem
Figure 1.2
Cells are the structural and functional units of life
• A cell
– Is the basic unit of life
• New proper ties emerge
– From the complex organization of a system, such as a cell
• All cells contain:
– DNA
– Cell membrane
– ribosomes
• Eukaryotic cells
– Contain membrane-enclosed organelles, including a DNA-containing nucleus
• Prokaryotic cells
– Lack such organelles
Eukaryotic cell
Prokaryotic cell DNA
(no nucleus) Membrane
Organelles
Nucleus (membrane-
enclosed) DNA
(throughout nucleus)
EVOLUTION, UNITY, AND DIVERSITY
The unity of life: All forms of life have common features
• DNA is the genetic information
– For constructing the molecules that make up cells and organisms
• Each species’ genetic instructions
– Are coded in the sequences of the four building blocks making up DNA’s two helically coiled chains
A
C
T
A
T
A
C
C
G
T
A
G
T
A
CG
C G
C G
C G
C
G
A T
AT
A TA T
AT
A
T
• All organisms share a common set of features
– Ordered structures
– Regulation of internal conditions
Figure 1.4B Figure 1.4C
– Growth and development
– Energy use
– Response to environmental stimuli
– The ability to reproduce and evolve
Figure 1.4D Figure 1.4E
The diversity of life can be arranged into three domains
• Organisms are grouped (classified)
– Into the prokaryotic domains Bacteria and Archaea and the eukaryotic domain Eukarya
Diversity of Life:
Living Things are categorized into
3 Domains: Bacteria
Archaea
Eukarya
Within the Domain of the Eukarya,
we distinguish :
4 Kingdoms: Plantae
Fungi
Animalia
Protista
SE
M 2
5,00
0!
Figure 1.5B
• Domains Bacteria and Archaea
SE
M 3
,250!
Figure 1.5A
• Domain Eukarya includes
– Protists (protozoans and algae, falling into multiple kingdoms)
– The kingdoms Fungi, Plantae, and Animalia
275!
Protists (multiple kingdoms)
Kingdom Fungi
Kingdom Animalia
Kingdom Plantae Figure 1.5C
Evolution explains the unity and diversity of life • Charles Dar win
– Synthesized the theory of evolution by natural selection
1
2
3
Populations with varied inherited traits
Elimination of individuals with certain traits
Reproduction of survivors
• Natural selection is an editing mechanism
– That occurs when populations or organisms, having inherited variations, are exposed to environmental factors that favor the reproductive success of some individuals over others
THE PROCESS OF SCIENCE
Scientists use two main approaches to learn about nature
• Science
– Is a way of knowing
– Seeks natural causes for natural phenomena
Discovery Science
• In discovery science
– Scientists describe some aspect of the world and use inductive reasoning to draw general conclusions
Jane Goodall
Hypothesis-Based Science
• In hypothesis-based science
– Scientists attempt to explain obser vations by testing hypotheses
In studying nature, scientists make observations and form and test hypotheses
All scientists use the Scientific Method to test a hypothesis.
7 Steps: 1. Observation 2. Question 3. Hypothesis 4. Prediction 5. Experiment 6. Results 7. Conclusion
Observations
Question
Hypothesis # 1: Dead batteries
Hypothesis # 2: Burnt-out bulb
Prediction: Replacing batteries will fix problem
Prediction: Replacing bulb will fix problem
Test prediction Test prediction
Results: Flashlight does not work. Hypothesis is falsified
Test does not falsify hypothesis
Scientific Method Observations
Question
Hypothesis
Test supports hypothesis; make additional predictions and test
them
Test does not support hypothesis; revise hypothesis
or pose new one Prediction
Test: experiment or
additional observation
Results / Data
Conclusion
• Biology is connected to many impor tant issues in our lives
– Environmental problems and solutions
– Genetic engineering
– Medicine