2. 1.1 The Diversity of Life Biology is the study of living things
Living things can be divided into six kingdoms
Protista
Archaea
Bacteria
Fig. 1.1
Animalia
Fungi
Plantae

3. 1.2 Properties of Life Biology is the study of life
But what does it mean to be alive?
Living organisms and many non-living things share three properties
Complexity
Movement
Response to stimulation

4. 1.2 Properties of Life
All living organisms share five basic properties
1. Cellular Organization
All living organisms are composed of at least one cell
2. Metabolism
All living organisms use energy
3. Homeostasis
All living organisms maintain stable internal conditions

5. 1.2 Properties of Life
All living organisms share five basic properties
4. Growth and reproduction
All living organisms grow and reproduce
5. Heredity
All living organisms possess a genetic system that is based on DNA
Deoxyribonucleic acid

6. 1.3 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
Populational Level

7. Fig. 1.4

8. Fig. 1.4

9. Fig. 1.4

10. 1.3 The Organization of Life
Each higher level contains novel properties not present at the simpler level of organization
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

11. 1.4 Biological Themes The living world is organized by major themes
Indeed, five general themes unify and explain biology as a science
Refer to Table 1.1

12. 1.4 Biological Themes 1. Evolution 2. The Flow of Energy
The genetic change in a species over time
It is a result of a process termed natural selection
Variation may also be caused by artificial selection
2. The Flow of Energy
All living organisms require energy
The sun is the source of energy for ecosystems
Plants capture energy via photosynthesis
They then act as an energy source for other organisms

13. 1.4 Biological Themes 3. Cooperation 4. Structure Determines Function
Cooperation between organisms is critical for evolution
Symbiosis occurs when two organisms of different species live in direct contact
4. Structure Determines Function
Biological structures are well suited to their function
This is true at every level of organization

14. 1.4 Biological Themes 5. Homeostasis
All living organisms act to maintain a relatively stable internal environment
Maintaining homeostasis requires a lot of signaling back-and-forth between cells

15. 1.5 How Scientists Think Deductive Reasoning
Using accepted general principles as a “guide” to explain specific observations
It is the reasoning of
Mathematics
Philosophy
Politics
Ethics
It is also how a computer works

16. 1.5 How Scientists Think Inductive Reasoning
Discovering general principles through examination of specific cases
It is used by scientists to develop hypotheses about how the world works

17. Fig. 1.5

18. 1.6 Science in Action: A Case Study
In 1985, a scientist discovered low levels of ozone in the upper Antarctic atmosphere
The culprit was later revealed to be chlorofluorocarbons (CFCs)
Coolants in air conditions; propellants in aerosols
CFCs condense into tiny ice crystals
Warmed by the sun, they attack and destroy ozone

19. Fig. 1.6 How CFCs attack and destroy ozone

20. 1.6 Science in Action: A Case Study
The ozone layer protects us from the sun’s ultraviolet (UV) rays
1% drop in ozone  6% increase in skin cancers
Its depletion is a serious world problem
So governments have rushed to correct the situation
There is now a worldwide reduction in CFC production
The ozone layer will recover by mid-21st century

21. 1.7 Stages of a Scientific Investigation
The scientific process can be divided into six stages
1. Observation
Careful observation of a process or phenomenon
2. Hypothesis
Guess regarding the observation
If more than one guess, alternative hypotheses are formed
3. Prediction
Expected consequences based on the correct hypothesis

22. 1.7 Stages of a Scientific Investigation
The scientific process can be divided into six stages
4. Testing
The hypothesis is tested through an experiment
5. Controls
A factor that influences a process is called a variable
In a control experiment, all variables are held constant
6. Conclusion
Based on the results of the experiment, a hypothesis is either accepted or rejected

23. Fig. 1.7 Observation Question Hypothesis 1 Hypothesis 2 Hypothesis 3
Potential
hypotheses
Reject
hypotheses
1 and 4
Experiment
Hypothesis 5
Hypothesis 3
Hypothesis 2
Remaining
possible
hypotheses
Reject
hypotheses
2 and 3
Experiment
Last remaining
possible hypothesis
Hypothesis 5
Predictions
Experiment 1
Experiment 2
Experiment 3
Experiment 4
confirmed

24. 1.8 Theory and Certainty
A theory is a set of hypotheses that have been tested many times and not rejected
It indicates a higher degree of certainty
However, there is no absolute truth in science
So the acceptance of a theory is provisional

25. 1.8 Theory and Certainty Note:
To scientists, a theory represents that of which they are most certain
To the general public, a theory represents lack of knowledge or a guess

26. 1.8 Theory and Certainty The scientific “method”
A series of logical “either/or” predictions tested by experiments to reject alternative hypotheses
This trial-and-error testing was once viewed as the way scientific progress is made
However, science is not done this way!
Insight and imagination are necessary to good scientific examination

27. 1.8 Theory and Certainty The limitations of science
It is limited to organisms and processes that can be observed and measured
Supernatural and religious phenomena are beyond the scope of science
There are also practical limits
Science cannot be relied upon to solve all problems

28. 1.9 Four Theories Unify Biology
1. The Cell Theory
2. The Gene Theory
3. The Theory of Heredity
4. The Theory of Evolution

29. The Cell Theory: Organization of Life
Robert Hooke, 1665
Discovered cells
Anton van Leeuwenhoek, 1670s
Discovered single-celled life
Matthias Schleiden & Theodor Schwann, 1839
All living organisms are composed of cells
Cells are the basic units of life
Rudolf Virchow, 1866
All cells come from other cells

30. The Gene Theory: Molecular Basis of Inheritance
The information that determines what an organism is like is encoded in its genes
Genes are located along DNA molecules
Refer to Fig. 1.11
The entire set of DNA instructions that specifies a cell is termed its genome

31. Fig The gene theory

32. The Theory of Heredity: Unity of Life
This theory was first advanced by Gregor Mendel in 1865
It basically states that genes of an organism are inherited as discrete units
Later, other biologists proposed the chromosomal theory of inheritance
Genes are physically located on chromosomes

33. The Theory of Evolution: Diversity of Life
This theory was first advanced by Charles Darwin in 1859
It attributes the diversity of the living world to natural selection
An essential component of this theory is that evolution involves “descent by modification”
All living organisms are related to one another in a common tree of life

34. Crocodiles are more closely-related to birds than to other reptiles
Fig. 1.15
The tree of life
Crocodiles are more closely-related to birds than to other reptiles

35. The Theory of Evolution: Diversity of Life
Biologists divide all living organisms into three great groups, termed domains
Bacteria
Archaea
Eukarya

36. Fig. 1.16
Simplest and most diverse;
Gave rise to the other three eukaryotic kingdoms
Prokaryotes