Bio Lab

Independent variable

The variable you manipulate in an experiment.

Dependent variable

Changes as a result of the independent variable.

Control variables

Everything held constant in an experiment.

Control group

Contains all control variables but no independent variable, used for comparison.

Positive control

A control that contains a known substance to produce a positive result.

Negative control

A control that contains no substance to produce the expected reaction.

Benedict’s test

A test for detecting reducing sugars; positive results indicate the presence of sugar.

Iodine test

A test to detect starch; a blue-black color indicates starch is present.

Biuret test

A test for proteins; purple color indicates the presence of protein.

Sudan IV test

A test for lipids; positive result shows cloudy white droplets.

Cellulose

A carbohydrate and insoluble fiber that humans cannot digest.

Hypothesis

A proposed explanation for an observation that can be tested.

Conclusion in experiments

Results indicate whether the hypothesis is supported or not.

Glassware examples

Volumetric flask, Erlenmeyer flask, graduated cylinder, beaker, pipette.

Mercury thermometer

A thermometer containing toxic mercury; requires special cleanup if broken.

Alcohol thermometer

A safer thermometer that can break without special protocol.

Microscope parts

Includes ocular lens, nosepiece, arm, stage, and objective lenses.

Reducing sugars

Simple sugars like glucose, detected using Benedict’s test.

Positive result for Iodine test

A blue-black color indicates the presence of starch.

Protein presence color change

The Biuret test turns purple in the presence of protein.

Lipid detection indication

Cloudy white droplets in the Ettanol test indicate lipids are present.

Scientific law

A statement based on repeated experimental observations that describes an aspect of the world.