1. Exploring Life Chapter 1
General Biology – Science Majors I – 1406

2. What is Biology?
Biology is the science of life and of living organisms, including their structure, function, growth, origin, evolution, and distribution.

3. Unifying Themes Three Major Groups: Exploring Life on Its Many Levels
Evolution, Unity, and Diversity
The Process of Science

4. 1. Exploring Life on Its Many Levels
Hierarchy of Biological Organization
Emergent Properties:
As we go up the hierarchy of biological order new properties emerge that were not present in the previous level.
Emergent properties result from the interactions between components.
Reductionism in Biology:
In order for biologists to understand the complex organization of living organisms they are faced with two problems:
1.) Biologists cannot fully explain a higher level of order by breaking it down into its parts.
Ex: If we dissect an animal, it cannot function anymore.
If we break apart a cell into its chemical ingredients the cell is not a cell anymore.
2.) Biologists are faced with the other end of the spectrum. If they are supposed to analyze a complex organism or as simple as a cell, how then are they supposed to do it without taking it apart. Thus, it is important for biologists to reduce systems to simpler components that are more manageable to study.
Ex: Study of DNA molecule

5. 2. Emergent Properties of Life
Reproduction
All organisms are capable of reproducing and passing their genetic material to their offspring.
Organisms reproduce only their own kind.
Life comes only from life.

6. Emergent Properties of Life
Growth and Development
All organisms are capable of growing.
DNA directs the pattern of growth and development of an organism.

7. Emergent Properties of Life
Utilization of Energy
All organisms use energy and transform it in order to do work.
Ex: Plants take in energy from the sun and transform it into chemical energy.
Ex: Bat gets its energy from the nectar from the saguaro cactus, and use it to fly and carry out its nocturnal activities.

8. Emergent Properties of Life
Homeostasis
Organisms maintain relatively constant internal conditions different to their environment through regulatory mechanisms
The blood vessels of the jackrabbit regulate the loss of heat to its environment.

9. Emergent Properties of Life
Evolutionary Adaptation
Organisms adapt to their environment.
This white-tailed ptarmigan has evolved white plumage and it is almost invisible against the snow. This adaptation protects it from predators.

10. Cells the Basic Units of Structure & Function
The Cell Theory
Three Basic Principles:
All organisms are made up of one or more cells
Cells are the smallest unit of life
Cells come from preexisting cells

11. Two Types of Cells Prokaryotic Cells Eukaryotic Cells Bacteria
Archaea bacteria
Eukaryotic Cells
All other organisms are composed of eukaryotic cells:
protists
fungi
plants
animals

12. Continuity of Life – DNA
DNA (Deoxyribunucleic Acid) is the hereditary blueprint in each cell of all living organisms.
Double helix
The two strands are held together by a base pairing.
Biological instructions are encoded in the DNA
DNA carries the units of inheritance that transmit information from parents to offspring.

13. Structure and Function
Structure and function are correlated at all levels of biological organization.
Birds have hollow bones which provide a strong lightweight skeleton.

14. Organisms Interact with their Environment
Organisms are open systems that exchange materials and energy with its surroundings.

15. Regulatory Mechanisms
Many biological processes are self regulating. They operate by a mechanism called feedback.
The product of the process regulates the process.
Two kinds of feedback:
Positive feedback speeds up the process
Negative feedback slows down or stops the process

16. The Kingdoms of Life (Carl Woese, University of Illinois)
Common Ancestor
Bacteria Archaea Eukarya (3 Domains)
Eubacteria Archaebacteria Protista Plantae Fungi Animalia
(Six kingdoms)
Three Domains and Six-Kingdom Classification System
The Kingdom was considered the highest – the most inclusive – taxonomic category in the classification of organisms until just recently. In the late 1990s this classification system was revised and the following classification system was proposed Organisms are grouped into three domains and six kingdoms.
Unicellular Organisms:
Unicellular organisms belong to the Bacteria and Archaea domains. These organisms are prokaryotes. Each of these domains consists of a single kingdom.
Multicelluar Organisms:
Multicellular organisms belong to the Eukarya domain. These organisms are eukaryotes. The Eukarya domain in turn has been divided into four kingdoms as follows:
* Kingdom Protista
* Kingdom Plantae
* Kingdom Fungi
* Kingdom Animalia
(Ref: Life the Science of Biology, 5th Edition, 1998)

17. Scientific Methodology
3. How do we do Science?
Scientific Methodology
observations and make generalizations
generate a question (s)
generate a hypothesis (tentative statement about the natural world)
formulate a testable prediction
design an experiment to test the prediction
if statistical analysis shows significant difference between the control group and the experimental group, your hypothesis is accepted, otherwise it is rejected
if rejected, then modify the hypothesis and repeat steps 3 and 4

18. What is a Hypothesis? Commonly
A hypothesis is an idea of “how things work”.
Formally
A hypothesis is a tentative answer to some question.

19. How do we test a hypothesis?
Hypothesis testing is based on deductive reasoning.
Deductive reasoning involves making a specific prediction about the outcome of an action and is based on observable facts.
Thus, deductive reasoning takes the “if/then” statements.

20. How Do We Test a Hypothesis?
We test the hypothesis by performing the experiment to see whether or not the results are as predicted.

21. Experimental Method Experiments are designed to test hypotheses.
Controlled Experiments
Control Group – data from a control group are used as baseline values for comparison to the measurements of the experimental group.
Experimental Group – data from the experimental group are compared against the control group and determine whether the hypothesis being tested is accepted or rejected.
Example of an unbiased experimental design:
Double-blind experiments

22. Double-Blind Experiments
Results from double-blind experiments produce more objective data.

23. Analysis of the Data
The data that is collected from an experiment must be statistically analyzed.
Statistically significant results indicate that there is a 5% probability or less that the results may be due to chance alone.
Types of statistical analysis include:
Correlation between two variables
Analysis of Variance
t-test
Multivariate tests
If the results of the statistical analysis do not support the hypothesis, then the hypothesis is rejected.

24. Evaluating Scientific Information
Primary Sources
New findings are published in scientific journals for peer review.
A group of scientists (peers) scrutinize the article before they approve it for publication
Scientific journals contain the most recent and accurate scientific information.
After a hypothesis has been tested extensively and the results support the hypothesis then the hypothesis becomes a theory.
A theory is the highest degree that a hypothesis can ever achieve.
Ex. Theory of Evolution by Charles Darwin provides a good example of how scientific theory grows and wins acceptance.

25. Critical Thinking Skepticism – questionable attitude
what are the credentials of the individual making the statement?
is there verifiable evidence to support the statement?
is there a political or monetary incentive behind the statement?
Most scientists are skeptical about radical findings
Ex. Stomach ulcers
The scientist who discovered that most stomach ulcers are caused by Heliobacter pylori bacteria encountered much ridicule from the scientific world because stomach ulcers were believed to be caused by stress.

26. Critical Thinking
The validity of a statement is supported by sound statistical analysis.
Beware of the claims made by nonscientists and even by some scientists.
If the claim states something like “scientific research proved that …” be very careful because
Scientific studies NEVER EVER prove anything.
Scientists conduct research to test a hypothesis, to disprove a hypothesis.

27. Are there any limitations to science?
Is science limited? YES !!!
Science is based on testable facts.
Science cannot be applied to:
religious beliefs because they are based on faith
faith cannot be tested
morals, value judgments, social issues, attitudes, love, or supernatural forces

28. Science is Self-Correcting
Science is limited by the ability of the scientists to collect data and interpret data.
New advances in technology have made it possible for science to correct misinterpreted data. New interpretation replaces the old incorrect information.
Example:
belief that the earth was merely 6000 years old.
belief that the sun revolved around the earth.