THE SCIENTIFIC METHOD

Scientific Method
- a logical and orderly procedure of investigation

STEPS:

Making observations
- process of using our senses to describe things and phenomena

Formulating a hypothesis
- data gathered from a set of observations
- hypothesis is a possible and reasonable explanation for the question or problem

Testing a hypothesis
- experiment is a designed procedure used to test the validity of a hypothesis

SETS OF VARIABLES

• Independent Variable - factor tested in the environment
• Dependent Variable - factor measured to determine the outcome
• Controlled Variable - one that can influence the outcome of an experiment

GROUPS

• Control Group - all except the independent variable applied
• Experimental Group - all of the variable are applied

Observing and recording experimental data

• any result should be recorded
• may include notes, tabulations, and graphs
• everything should be recorded accurately

Drawing Conclusions

- must be entirely based on the results gathered from the experiment

Theory - a hypothesis that has been repeatedly and rigorouly tested

Law or Principle - when theory has been proven to be consistently true and has passed the test of time

IMPORTANT TOOLS IN BIOLOGY

Microscopes

- instrument that uses lenses to produce an enlarged and focused image of a specimen

2 Important Properties

Magnification- ratio between the image size and the object size

Resolution - refers to the smallest degree of separation

KINDS OF MICROSCOPE

Compound Light Microscope - focuses and bends light through a speimen to produce a magnified image

Stereomicroscope - also known as the dissecting microscope

- it has also lower magnification than that of the compound microscope. This is used for dissecting small specimens

Electron Microscope - uses a beam of electrons instead of light to create an image

• Transmission Electron Microscope (TEM) - uses a magnetic field beam to focus a beam of electrons through a thin section of the specimen. Can magnify the image of an object about 100 000 times
• Scanning Electron Microscope (SEM) - gives a surface view of a three-dimensional specimen. Can magnify the image of an object about 10 000 times
• Scanning Tunneling Microscope (STM) -allows viewing of atoms on the surface of a solid. It can magnify a specimen over 100 million times. It has a needle probe with a joint so sharp that only one atom is at its point,

OTHER SCIENTIFIC TOOLS

Ultracentrifuge - a machine used to separate suspended particles in a mixture

Chromatography - used in separating substances in a mixture

Electrophoresis - used to separate substances in a mixture according to how fast they move when subjected to an electric current

X-Ray Diffraction - very useful for the analysis of protein crystals using x-rays of a single wavelength.

Spectrophotometer - a device used to determine the amount of proteins or nucleic acid present in a solution

Computer - very useful in storing vast amounts of information. It is also used to organize data, make long and complex calculations, and make graphs