1. CHAPTER 1 Introduction: The Scientific Study of Life
Modules 1.1 – 1.3

2. Life in the Trees
The lives of gray-headed flying foxes are closely entwined with the lives of the eucalyptus trees that form their habitat
Eucalyptus trees provide food and roosting sites for the flying foxes
Flying foxes aid in eucalyptus pollination and help disperse the resulting seeds

3. Flying foxes are becoming an endangered species, partly because of habitat destruction

4. Biology is the scientific study of life
THE SCOPE OF BIOLOGY
Biology is the scientific study of life
Interactions between different kinds of organisms affect the lives of all
Recall the example of flying foxes and eucalyptus trees

5. Big Themes throughout the year
Organization
Hierarchy
Structure and Function
Evolution

6. 1.1 Life’s levels of organization define the scope of biology
A structural hierarchy of life, from molecules to ecosystems, defines the scope of biology
An ecosystem consists of:
all organisms living in a particular area
all nonliving physical components of the environment that affect the organisms (soil, water)

7. At the top of life’s hierarchy is the ecosystem
ECOSYSTEM LEVEL Eucalyptus forest
Ecosystems include:
all the organisms in an area, which make up a community
interbreeding organisms of the same species, a population
COMMUNITY LEVEL All organisms in eucalyptus forest
POPULATION LEVEL Group of flying foxes
ORGANISM LEVEL Flying fox
Brain
Spinal cord
ORGAN SYSTEM LEVEL Nervous system
ORGAN LEVEL Brain
Nerve
TISSUE LEVEL Nervous tissue
CELLULAR LEVEL Nerve cell
MOLECULAR LEVEL Molecule of DNA
Figure 1.1

8. Organisms are made up of:
organ systems
organs
tissues
Cells  organelles
molecules
ECOSYSTEM LEVEL Eucalyptus forest
COMMUNITY LEVEL All organisms in eucalyptus forest
POPULATION LEVEL Group of flying foxes
ORGANISM LEVEL Flying fox
Brain
Spinal cord
ORGAN SYSTEM LEVEL Nervous system
ORGAN LEVEL Brain
Nerve
TISSUE LEVEL Nervous tissue
CELLULAR LEVEL Nerve cell
MOLECULAR LEVEL Molecule of DNA
Figure 1.1

9. 1.2 Scientists use two main approaches to learn about nature
THE PROCESS OF SCIENCE
1.2 Scientists use two main approaches to learn about nature
In discovery science, scientists describe some aspect of the world and use inductive reasoning to draw general conclusions
Example: scientists have described how newborn flying foxes cling to their mother’s chest for the first weeks of life
* Based on observations and measurements
Figure 1.2

10. In hypothesis-driven science, scientists use the “scientific method”
They propose a hypothesis
They make deductions leading to predictions
They then test the hypothesis by seeing if the predictions come true

12. 1.3 With the scientific method, we pose and test hypotheses
Observation
The main steps of the scientific method
Question
Hypothesis
Prediction
Test does not support hypothesis; revise hypothesis or pose new one
Test supports hypothesis; make additional predictions and test them
Test:
Experiment or additional observation
Figure 1.3A

13. Deductive reasoning is used in testing hypotheses
If a hypothesis is correct, and we test it, then we can expect a particular outcome
Case study: flashlight failure
What do we do and what are possible outcomes? Discuss with partner
Figure 1.3B

14. Experiments designed to test hypotheses must be controlled experiments
Control groups must be tested along with experimental groups for the meaning of the results to be clear
Controls provide comparison and must be repeatable
A good hypothesis is testable and falsifiable

15. Variables
Independent variable – factor manipulated in experiment
Dependent variable – factor being measured that is predicted to be affected by independent variable.

16. Case study: spider mimicry
Figure 1.3C
So what do you notice between the spider and the fly?
Explain the graph to the right.
Pounce rate (% of trials in which spider jumped on fly)
Control group (untreated flies)
Experimental group (wing markings masked)
Figure 1.3D

17. Another test of the spider mimic hypothesis: wing transplants
Number of stalk and attack responses by spiders
Wing markings
Wing waving
Normal spider mimic
Mimic with mimic wing transplant
Mimic with housefly wing transplant
Housefly with mimic wing transplant
Normal housefly
Figure 1.3E
Controls
Experimentals

18. 1.4 The diversity of life can be arranged into three domains
EVOLUTION, UNITY, AND DIVERSITY
1.4 The diversity of life can be arranged into three domains
Grouping organisms by fundamental features helps make the vast diversity of life manageable for study
Scientists classify organisms into a hierarchy of broader and broader groups

19. Most classification schemes group organisms into three domains:
Domain Bacteria
common E.coli/Staph
Domain Archaea
Extreme hot/salt
Figure 1.4A, B

20. Domain Eukarya
Figure 1.4C-F

21. Know basic characteristics of each Domain as well as the eukaryotic Kingdoms.
Plants
Fungi
Animalia
Protists

22. 1.5 Unity in diversity: All forms of life have common features
All organisms share a set of common features, signs of unity in life’s vast diversity
All are made of cells
All have DNA as their genetic blueprint
These orchids show the variety possible within one species
Figure 1.5A

23. DNA is made of chemical units called nucleotides
Each species has its own nucleotide sequence
Figure 1.5B

24. DNA is universal – all life uses 4 bases.
A particular sequence of nucleotides means the same thing even if in different organisms.
Protein hemoglobin binds oxygen but can track evolutionary changes in DNA for hemoglobin
Differences between organisms is due to differences in sequence (order) vs. code
Similarities potentially show evolutionary trends.

25. The genetic information in DNA underlies all of the features that distinguish life from nonlife
Order and regulation
Growth and development
Use of energy from the environment
Response to environmental stimuli
Ability to reproduce
Evolutionary change

26. 1.6 Evolution explains the unity and diversity of life
Charles Darwin is a central figure in biology
He synthesized the theory of evolution by natural selection
A theory in science is a comprehensive idea with broad explanatory power
Evolution is the core theme of biology
Figure 1.6A

27. Species change over time as they accumulate changes due to different environments – descent with modification.
Natural selection is due to descent with modification

28. The theory of natural selection explains the main mechanism whereby all species of organisms change, or evolve
(1) Population with varied inherited traits
(2) Elimination of individuals with certain traits
Figure 1.6B
(3) Reproduction of survivors

29. With your group
Pick an organism and then decide which adaptations make it uniquely suitable for where it is found. Why these adaptations for this environment? Is there a better way, or what might happen in the future?

30. Evolution happens when populations of organisms with inherited variations are exposed to environmental factors that favor the success of some individuals over others
Natural selection is the editing mechanism
Evolution is based on adaptations
Figure 1.6C

31. Darwin observations
  Individuals vary in their traits (many passed from parent to offspring).
  Organisms seem to produce more offspring than the environment can support.
  Species suited to environment
Organisms are not created but constantly edited to fit

32. Evolutionary tree

33. Think about it - question
Explain why editing is an appropriate metaphor for how natural selection acts on a population’s heritable variation.

34. Think about it – possible answer
Those with traits better suited to environment are more likely to reproduce. Those offspring better suited then other offspring and have advantage (until environment changes)

35. 1.7 Living organisms and their environments form interconnecting webs
The theory of natural selection applies to all levels in life’s hierarchy
In an ecosystem, these interactions make up a complex web of relationships
The functional aspects of an ecosystem come from the structure of the ecosystem’s web
This is an interaction of living and non-living components.

36. A web of interactions in a rain forest ecosystem
Figure 1.7A

37. Plants, or plant products, are the ultimate sources of food in an ecosystem
This African sunbird is consuming nectar, a plant product
Figure 1.7B

38. Cycling of chemical nutrients
Chemical nutrients cycle within an ecosystem’s web
Energy flows in and out constantly
Matter gets recycled
Sun
Inflow of light energy
Loss of heat energy
Air
Chemical energy
Cycling of chemical nutrients
Organisms
Soil
Figure 1.7C
ECOSYSTEM

39. 1.8 Connection: Biology is connected to our lives in many ways
BIOLOGY AND EVERYDAY LIFE
1.8 Connection: Biology is connected to our lives in many ways
Biology is connected to a great number of important issues
Environmental problems and solutions
Genetic engineering
Medicine
Figure 1.8A

40. Many technological advances stem from the scientific study of life
Evaluating everyday reports in the press about a large range of subjects requires critical thinking and some familiarity with many areas of biology
In order to understand how rain forest destruction impacts global climate, it is important to understand biology from the molecular to the ecosystem level
Figure 1.8B