1. Chapter 1: The Science of Biology

2.   Science is:
The Goal of Science is to investigate and understand nature, to explain events in nature and to use those explanations to make predictions.
Scientists collect and organize information carefully and look for patterns or connections between events.
Scientists propose explanations for events that can be tested through experimentation.
Science: an organized way of using evidence to learn about the natural world.
The word science also refers to the body of knowledge that has been built up over the years

3. Evidence is based on observation
Observation: using one or more of the senses to gather information.
Any information gathered through observation is known as Data.
There are two types of Observations: Qualitative and Quantitative.
Qualitative: involve characteristics that can not be counted or numbered such as color and texture
Quantitative: involve numbers or calculations

4. Interpreting the Evidence
Observations alone have little meaning in science, because they do not tell us how anything actually works.
Scientists often follow up their observations by making inferences
Inference: a logical interpretation based on prior knowledge and experience.

5. Explaining the Evidence
Inferences can be taken a step further and become a hypothesis
Hypothesis: a possible explanation for a set of observations that can be tested through experimentation
A hypothesis can arise in several ways. It can come from prior knowledge, logical inferences or even educated guesses
The key to any hypothesis is that it is testable
The best way to test a hypothesis is through a Controlled Experiment

6. Designing an Experiment
When a scientist designs an experiment to test his/her hypothesis, they should follow the scientific method
The scientific method has 5 main parts
1.  State the Problem
2.  Form a hypothesis
3.  Set up a controlled experiment
4.  Record and Analyze your data
5. Draw a Conclusion

7. An example of following the scientific method: Francesco Redi’s Experiment
For centuries, people noticed that maggots would appear on meat after a certain amount of time had passed
People believed that Spontaneous Generation, which essentially means that life could arise from non-living things, was causing the maggots presence
In 1668 an Italian physician named Francesco Redi proposed a different hypothesis about where these maggots were coming from

8. Redi 2
He noticed that the maggots were appearing a few days after flies had been observed on the meat and proposed that the flies were laying eggs that were too small to be seen on the meat
Redi designed a controlled experiment in which he could test his theory
Controlled Experiment: type of experiment I which only one variable is changed at a time, while all other variables are unchanged and used as a control

9. Redi 3
Manipulated Variable: variable that is deliberately changed in an experiment to see how it effects the outcome of the experiment.
Responding Variable: variable that changes in response to the change in the manipulated variable

10. Redi 4
Redi set up two sets of jars. In both sets of jars he placed identical pieces of meat (at the same time and temperature). He covered one set of jars and left the other set uncovered
After several days passed, Redi observed flies around both jars. When he checked the contents of the jars, the uncovered jars contained maggots, but the covered jars did not
With this experiment, Redi was able to disprove the theory of Spontaneous Generation

11. Repeating Investigations
In order for experimental results to be considered valid, the experiment must be repeatable
If the results of the experiment are generally the same every time it is performed, once can conclude that the findings are sound

12. Several scientists tried to confirm or refute Redi’s work
After Redi performed his experiment, Anton van Leeuwenhoek invented the microscope, which allowed scientists to see objects that are not readily visible to the naked eye
After the invention of the microscope, scientists discovered several miniscule moving objects on the surface of larger objects
They were not sure if these “things” were alive or not, so they decided to call them animalcule. (Animal + Molecule)

13. Needham
In the mid 1700s, John Needham tried to prove that these animalcules were the product of spontaneous generation
He boiled a flask filled with gravy, killing any living things inside of the gravy
He then let the flask sit for several days and discovered that it was filled with animalcules
He inferred that these animalcules could only have come from the gravy

14. Spallanzani
Later, another scientist, Lazzaro Spallanzani decided to test Needham’s work to see if it held up
He set up two separate flasks of gravy and boiled them both
He then sealed one of the flasks and let the other remain open

15. Spallanzani 2
When Spallanzani checked the flasks he found that the sealed flask had no new organisms in it, while the open flask was filled with organisms
He believed that the organisms had to come from the air
Despite these findings, several people still refused to accept that spontaneous generation could not exist

16. Pasteur Louis Pasteur finally put this issue to rest in 1864
He set up a flask with a long curved neck. This allowed for the air to reach the broth, but the curvature prevented any microorganisms from reaching the broth
He found that as long as the neck was attached, no new organisms grew in the broth, but as soon as the neck was removed, the organisms began to grow

17. Pasteur 2
He proved that the microorganisms were in the air, but did not come from the air
Pasteur proved once and for all that spontaneous generation did not exist

18. How a Theory Develops
When a hypothesis has be well supported by repeated experimentation, it may be considered a Theory
Theory: a well tested explanation that unifies a broad range of observations
A theory will allow scientists to make accurate predictions about future events
No theory can be considered the absolute truth, because as new evidence is discovered, theories can be altered or updated

19. Section 1-3
Studying Life

20. Characteristics of Living Things
Biology: the science, which seeks to understand the living world
There are 8 Characteristics of living things
1.  Living things are made up of cells
2.  Living things reproduce
3.  Living things are based on a genetic code
4.  Living things grow and develop

21. More Characteristics 5. Living things obtain and use Energy
6.  Living things respond to their environment
7.  Living things maintain a stable internal environment
8. Living things change over time

22. Made up of Cells
All living things, or organisms, are made up of small self contained units called cells
a Cell is a collection of living matter enclosed by a barrier that separates the cell from its environment
Cells are the smallest unit of an organism that can be considered alive
Cells can grow, respond to their environment and reproduce

23. Cells 2 Cells are complex and highly organized
Organisms can be unicellular (having only one cell) or multi-cellular (having more than one cell)
In multi-cellular organisms, each type of cell is specialized to perform a different function

24. Reproduction
All organisms produce new organisms through a process called reproduction
There are two types of Reproduction
Sexual Reproduction is a type of reproduction in which two cells from different organisms are combined to produce the first cell of a new organism
Asexual Reproduction is a type of reproduction in which there is only one parent
Either a single celled organism divides to produce a new single celled organism or a portion of an organisms breaks off the parent organism and produces an offspring (Budding)

25. Genetic Code Offspring tend to look somewhat similar to their parents
This is due to the passing on of genetic information through DNA
DNA determines the inherited traits of all organisms

26. Growth and Development
Each type of organism has a distinct life cycle
A life cycle is a particular pattern of growth and changes that occur over the lifespan of an organism
Development is a process through which organisms change to meet sexual maturity

27. Need for Energy Organisms need Energy to maintain their Metabolism
Metabolism: set of chemical reactions through which an organism builds up or breaks down materials as it carries out life processes
Most organisms acquire Energy from either Photosynthesis or Cellular Respiratration

28. Response to Environment
All organisms respond to external stimuli from their environment

29. Maintain Homeostasis
Homeostasis: process by which organisms keep their internal conditions relatively stable
Organisms are constantly regulating their internal environment

30. Organisms Evolve Organisms as a group will change over time
Over a generation or two theses changes may seem small, but over thousands of years, species can change dramatically

31. Branches of Biology
The diversity of life is so great that no biologist can study everything
Biology is organized into branches or divisions
Some branches are based on the type of organism being studies such as botany and zoology, while other branches like Paleontology are based on specific perspectives
No matter what the branch of biology is, the same approach is taken

32. Branches 2
Things must be understood at different levels of organization
Each level is a system made up of smaller parts, and often each level is part of the level above it
The levels of organization are as follows: Biosphere, Ecosystem, Community, Population, Organism, Groups of Cells, Cells and Molecules

33. Section 1-4
Tools and Procedures

34. A Common Measuring System
Most scientists use the metric system when collecting data and performing experiments.
The Metric System is a decimal system based on certain physical standards who’s units are scaled in multiples of 10
Scientists uses a revised version of the metric system known as the SI System of measure.

35. Common SI Units Length is measured in Meters
Volume is measured in Liters
Mass is measured in Kilograms
Temperature is measured in Kelvin

36. Length Some common conversions involving length
1m = 100 cm 1m = 1000mm
1km = 1000m 1inch = 2.54cm
1ft = 12 in 3ft = 1 yard
1 mile = 1760 yards = 5280 ft

37. Volume Some common conversions involving volume 1L = 1000 ml
1 kL = 1000 L
1ml = 1 cm3

38. Mass Some common conversions involving mass 1kg = 1000g 1g = 1000mg
1g = 100 cg
1kg = 2.2 lbs (pounds)

39. Temperature Some common temperature conversions K = oC + 273o
oC = K – 273o
oF = 9/5 oC + 32
oC = 5/9 (oF – 32)

40. Analyzing Biological Data
Biologists often use graphs and tables to organize the data they have collected.
This is done so that they can visualize changes over time.
Good examples of biological graphs and tables appear on page 25 in your text book

41. Microscopes
Microscope: a device which produces magnified images of structures that are too small to see with the unaided eye.
The most commonly used type of microscope is the Light Microscope.
Light Microscopes produce magnified images by focusing visible light rays.

42. Light Microscopes
Light microscopes can have a magnification up to 1000x.
Compound Light Microscopes: allow light to pass through the specimen and uses two lenses to form a magnified image.

43. Electron Microscopes
Electron Microscopes produce magnified images by focusing beams of electrons.
These microscopes are capable of 1000x the magnification of a light microscope.
All specimen placed under an electron microscope must be completely dried out.
There are two sub-types of electron microscopes
The transmission electrom microscope (TEM) shines a beam of electrons through the specimen while the scanning electron microscope (SEM) runs a beam of electrons repeatedly over the surface of the specimen. (The SEM produces 3-D images)

44. Laboratory Techniques
To obtain enough material to study, biologists often create a cell culture.
Cell Culture: group of cells grown in a nutrient solution from a single cell.
Once the culture is grown, the cells can be subjected to tests to see how they respond to various stimuli.

45. Laboratory Techniques 2
Cells can be broken down into their component parts through the process of Cell Fractionation.
The cells are places in a special blender to break the cell into bits.
Then the bits are submerged in a liquid inside of a test tube.
The tube is then placed into a centrifuge that spins the tube causing the parts to separate.
The parts separate based on their density and the biologist can then go pick out what they want.