1. Ch 1 – The Science of Life

2. The World of Biology Biology: The study of life
Characteristics of life
Organization and Cells
Response to Stimuli
Homeostasis
Metabolism
Growth and Development
Reproduction
Change Through Time

3. Organization and Cells
All living things are composed of one or more cells
Cells are the smallest units that can perform all life’s processes
In multicellular organisms, many are specialized to perform specific functions
Cells are always very small
The size of multi-celled organisms depends on the number of cells NOT their size 3

4. Organization and Cells, cont.
Organized at both the molecular and cellular levels
Take in substances from the environment and organize them in complex ways
Specific cell structures (organelles) carry out particular functions 4

5. In multicellular organisms, cells and groups of cells are organized by their function (hierarchy of life)
Atom  Biological Molecule  Organelle  Cell  Tissue  Organ  Organ System  Organism 5

6. Response to Stimuli
Organisms can respond to a stimulus, or a physical or chemical change in the internal or external environment 6

7. Homeostasis
The maintenance of a stable level of internal conditions even though environmental conditions are constantly changing, (like: body temperature, water content, glucose levels)

8. Metabolism PHOTOSYNTHESIS
The sum of all the chemical reactions that take in and transform energy and materials from the environment
PHOTOSYNTHESIS

9. Growth and Development
All living things grow and increase in size from the division and enlargement of cells
Development is the process by which an organism becomes a mature adult; involves cell division and cell differentiation, or specialization

10. Reproduction
Production of new organisms is essential for the continuation of a species
Hereditary information is transferred to offspring during two kinds of reproduction
Sexual reproduction – hereditary information recombines from two organisms of the same species
Asexual reproduction – hereditary information from different organisms is not combined ~ original and new organisms are genetically the same

11. Evolution or Change Through Time
Populations of living organisms evolve or change through time to better adapt to changing conditions
Charles Darwin’s SURVIVAL OF THE FITTEST through the process of natural selection

12. THEMES IN BIOLOGY Diversity and Unity Unity in the Diversity of Life
Three Domains of Life
Interdependence of Organisms
Evolution of Life
Natural Selection

13. Unity in the Diversity of Life
Genetic code: rules that govern how cells use the hereditary information in DNA (deoxyribonucleic acid – makes up our genes or instructions for life)
Presence of organelles: carry out all cellular activities
“Tree of Life” – suggests all living things have descended with modification from a single common ancestor; thus, all of life is connected

14. Three Domains of Life Bacteria Kingdom Bacteria (Eubacteria) Archaea
Kingdom Archaea (Archaebacteria)
Eukarya
Kingdom Animalia
Kingdom Plantae
Kingdom Fungi
Kingdom Protists

15. Interdependence of Organisms
Ecology: branch of biology that studies organisms interacting with each other and with the environment
Ecosystems: communities of living species and their physical environments; e.g., minerals, nutrients, water, gases, heat, etc.

16. Evolution of Life
Descent with modification: process in which the inherited characteristics within populations change over generations, such that genetically distinct populations and new species can develop
Natural Selection: organisms that have certain favorable traits are better able to survive and reproduce successfully than organisms that lack these traits
Adaptations: traits that improve an individual’s ability to survive and reproduce

17. Scientific Method

18. Scientific Processes and Methods
1. Observations/Questioning
2. Measuring, Organizing Data, and Classifying
3. Hypothesizing -- a testable explanation based on experience, reading, and/or previous experiments. (NOT A GUESS)
Inductive Reasoning
4. Predicting -- stating in advance the result that will be obtained from testing
Deductive Reasoning (If…then…statement)

19. Scientific Method, cont.
5. Experimenting -- A controlled procedure for testing a hypothesis
Control Group -- all conditions remain constant
Experimental Group -- same as control, except for ONE factor
Variable
Independent Variable - condition that changes
Dependent Variable - response to changed condition
Data
Qualitative ~ descriptive (think quality)
Quantitative ~ numbers (think quantity)

20. Scientific Method, cont.

21. Scientific Method, cont.
6. Organizing and Analyzing Data

22. Scientific Method, cont.
7. Inferring Conclusions (concluding from evidence collected during experimentation using facts and previous knowledge rather than direct observations)
8. Modeling and Communicating
9. Test and Re-test ~ law or theory formed

23. Scientific Method, cont.
LAW -- general statement that describes a wide variety of phenomena
If a hypothesis describes HOW things happen and continues to be supported by evidence, it becomes a law.
THEORY -- most probable explanation for a set of data based on best available evidence
If a hypothesis describes WHY things happen and continues to be supported by evidence, it becomes a theory.

24. Scientific Method -- Example
Observations:
Fish populations in Twin Lakes are declining.
The pH (acidity) of the water in the lakes is dropping to 4.2.
One hundred miles west of Twin Lakes is a power plant that is burning tons of coal every year, releasing sulfur dioxide into the air.

25. Problem Twin Lakes -- Acid Rain Problem East Branch West Branch
100 miles
East Branch
West Branch
Power Plant

26. Questioning/Hypothesizing (Inductive Reasoning)
Question: Is there a link between the power plant, the pH of the lake, and the fish decline?
Hypothesis: If acid rain falling on Twin Lakes is related to fish reproduction, then increasing acid rain amounts will cause the fish to have poor reproduction.

27. Experiment Experiment
Twin Lakes is a lake in the mountains that can be divided by a barrier.
A complete inventory will gather baseline data.
One arm of the lake, on the east side of the barrier, will be treated with sulfuric acid to reduce the pH to 4.0.
The west arm of the lake will be left alone, other than monitoring.

28. Experiment Twin Lakes -- Acid Rain Problem East Branch West Branch
100 miles
East Branch
West Branch
Barrier
Power Plant
Acid Rain Added
No Acid Added

29. Results East Branch: Fish stop reproducing. West Branch:
No change in fish reproduction.

30. Conclusion
The power plant emits sulfur dioxide into the air which combines with rain to produce acid rain. The addition of this acidic rain to the lakes lowers the pH and causes the fish to stop reproducing. This results in declining fish populations and jeopardizes the survival of the fish.