Scientific Methods Quiz

Study Notes

An independent variable is a factor that is changed or manipulated by the experimenter.
It is the presumed cause in the experiment.

A dependent variable is the factor that is measured or observed in an experiment.
It is the presumed effect in the experiment.

A control group is a group that does not receive the treatment or manipulation being studied.
An experimental group receives the treatment or manipulation.
This allows researchers to compare the results of the control group to the experimental group to see if the treatment had an effect.

Constants are factors that are kept the same or controlled for in an experiment.
This helps ensure that any observed changes in the dependent variable are due to the independent variable, not other factors.

Eyepiece: The lens you look through to view the specimen.
Objective Lenses: Lenses that magnify the specimen, usually have different magnifications.
Stage: The platform where the slide with the specimen is placed.
Condenser: Focuses light onto the specimen.
Diaphragm: Controls the amount of light that passes through the condenser.
Light Source: Provides illumination for viewing the specimen.
Fine Adjustment Knob: Used for precise focusing.
Coarse Adjustment Knob: Used for initial focusing.
Base: The bottom of the microscope, provides stability.
Arm: Connects the base to the body tube.

Magnification of a microscope is determined by multiplying the magnification of the eyepiece by the magnification of the objective lens being used.
Example: If the eyepiece has a magnification of 10x and the objective lens has a magnification of 40x, the total magnification is 10x * 40x = 400x.

Always carry the microscope with two hands (one hand under the base and the other holding the arm).
Clean the lenses with lens paper after each use.
Use only proper cleaning solutions for lenses.
Avoid touching the lenses with your fingers.
Do not force the knobs or adjust the microscope in a way that might break it.
Properly store the microscope in a dust-free environment.

The factor that is measured or observed in an experiment. It is affected by the independent variable.

The group that does not receive the treatment or manipulation of the independent variable. It serves as a baseline for comparison.

The group that receives the treatment or manipulation of the independent variable. It is compared to the control group to determine the effect of the independent variable.

Factors that are kept the same or unchanged throughout an experiment.
They help ensure that any observed differences in the dependent variable are due to the independent variable and not other factors.

Eyepiece: The lens you look through, typically 10x magnification.
Objective Lenses: Multiple lenses with varying magnifications, mounted on a revolving nosepiece.
Stage: Platform where the slide is placed.
Stage Clips: Devices used to hold the slide securely in place.
Diaphragm: Controls the amount of light passing through the specimen.
Light Source: Provides illumination for viewing the specimen.
Coarse Adjustment Knob: Moves the stage up and down for initial focusing.
Fine Adjustment Knob: Used for precise focusing.
Base: The stable bottom of the microscope.
Arm: Supports the eyepiece and objective lenses.

Magnification = Eyepiece Magnification x Objective Lens Magnification
Example: If the eyepiece is 10x and the objective is 40x, then the total magnification is 400x.

Start with the lowest power objective lens (usually 4x).
Use the coarse adjustment knob to move the stage up or down until the specimen is roughly in focus.
Use the fine adjustment knob to make the image sharper.
If necessary, switch to higher power objectives and refocus using only the fine adjustment knob.

Always carry the microscope with one hand on the arm and the other hand supporting the base.
Do not touch the objective lenses with your fingers, as this can damage them.
Use lens paper to clean the lenses.
Never force the stage or knobs.
Turn off the light source when finished.