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

3. THE SCOPE OF BIOLOGY
Biology is the scientific study of life
Interactions between different kinds of organisms affect the lives of all

4. 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)

5. 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

6. Organisms are made up of:
organ systems
organs
tissues
cells
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

7. 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
Figure 1.2

8. In hypothesis-driven science, scientists use the “scientific method”

9. 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

10. Observation Skills
Observe the following scene quietly for 30 seconds.

12. Are there cars parked on the sides of the road?
What color is the pickup truck driving in the road?
Any minivans around?
What does the blue sign say?
What's the speed limit?
Are there any pedestrians on the road?

14. Eye Witness
1 witness, 1 investigator

16. 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
Figure 1.3B

17. Experiments designed to test hypotheses must be controlled experiments
Control groups must be tested along with experimental groups for comparison

18. Case study: spider mimicry
Figure 1.3C
Pounce rate (% of trials in which spider jumped on fly)
Control group (untreated flies)
Experimental group (wing markings masked)
Figure 1.3D

19. 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

20. 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

21. order of taxa in biology
(Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species)
Dear King Philip Come Over For Good Soup

22. Most classification schemes group organisms into three domains:
Domain Bacteria
No nucleus
1 chromosome
Domain Archaea
Figure 1.4A, B

23. Domain Eukarya - cells have a membrane bound nucleus and organelles
Figure 1.4C-F

24. 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
Figure 1.5A

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

26. 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

27. 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

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. 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

30. 1.7 Living organisms and their environments form interconnecting webs
The theory of natural selection applies to all levels in life’s hierarchy
Video: #75 (natural selection CCR)
In an ecosystem, these interactions make up a complex web of relationships

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

32. 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

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

34. 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

38. Process of Science (1.3)

39. Observation
A farmer notices that his neighbors wheat yields are consistently higher than his own.

40. Testable Question
What causes the other farmers fields to produce more grain?

41. Possibilities Farming Practices Variety of Seed Time of planting
Summer fallow
Fertilizing
Pesticides

42. Outside Factors Less moisture due to varying weather patterns
Poor Soil
Other Neighbors fields holding pests

43. Hypothesis
The farmer thinks that it is most likely the result of the seed variety.

44. Prediction
If the farmer plants the same seed variety as his more successful neighbor, then his yields will be higher than with the old variety.

45. Controlled Experiment
Independent Variable – The variable that will be changed by the conductor of the experiment.
The variety of wheat seed

46. Controlled Experiment
Dependent Variable – The variable that will be measured to determine the effect of the Independent Variable.
The wheat yield

47. Controlled Experiment
Controlled Variables – The variables that may have an effect on the dependent variable, but are not being tested, so must remain the same.
Fertilizer, time of planting, seeding rate, moisture, weather damage, etc.

48. Controlled Experiment
Controlled Variables – The variables that will not be allowed to change. Any measured difference will be due to the effect of the Independent Variable.
Fertilizer, Pesticide, Time of Planting, Weather

49. Controlled Experiment
Experimental Group- the group in which the Independent variable is changed.
Control Group- group in which the independent variable is left unchanged. Controls other possible variables, used for comparison.

50. Controlled Experiment
The farmer 10 separate strips and alternately plants 5 strips to his old variety and 5 to the new variety.
The field is treated exactly the same for each variety.

51. Field

52. Results The farmer carefully harvests one variety and then the other.
The new variety yields a total of 2,017 bushels, while his old variety yields 2,156 bushels.

53. Conclusions
The farmer decides that the seed variety is not the factor that causes his neighbors yields to be higher.

54. Start Over
The farmer thinks the next most likely variable is fertilizer.
He repeats his experiment, this time using only one seed variety, while fertilizing one set of strips and not fertilizing the other.

55. Results The fertilized strips yield 2,562 bushels.
The unfertilized strips yield 1,985 bushels.

56. Conclusions
The farmer decides that the fertilizer made a drastic difference in yield and then compared the cost of the fertilizer with the yield increase.
He then fertilized all of his cropland before planting.

57. (1.6)
Evolution explains the Unity and Diversity of Life

58. Sexual Selection Gene Indicators Preferential Mating
Individuals with “Good Gene” indicators are selected more for mating and pass on more genes to the next generation.

62. Common Characteristics of Living Things
Order – complex organization (cells)
Regulation – maintain internal environment (Homeostasis)
Growth and Development
Utilize Energy
Respond to the environment
Reproduction
Evolution