lab midterm

What does PPE stand for in lab safety?

Personal Protective Equipment.

What temperature does water freeze in Fahrenheit?

32 ℉.

What is the pH scale range?

1-14.

What defines an acid?

An acid is a substance that donates H+.

What does the biuret test for?

Protein.

How do you carry a microscope?

By the arm with one hand and supporting the base with the other hand.

What is diffusion?

The process by which molecules move from an area of higher concentration to an area of lower concentration.

What should you do during a fire drill in the lab?

Turn off and unplug hot plates and other heated equipment.

What are the functions of the fine adjustment knobs on a microscope?

For precise focusing at higher magnifications.

What are the functions of the coarse adjustment knobs on a microscope?

For general focusing at low magnification.

What is the total magnification for low power on a microscope?

40X (10x ocular lens × 4x objective)

What is the total magnification for medium power on a microscope?

100X (10x ocular lens × 10x objective)

What is the total magnification for high power on a microscope?

400X (10x ocular lens × 40x objective)

What does methylene blue stain do?

Stains the nucleus and other cellular components to make them visible.

What is the tare function used for on a scale?

To zero out the mass of the container (weigh boat) so only the mass of the substance is measured.

Where should the meniscus be read in a graduated cylinder?

At eye level.

Why is a graduated cylinder more accurate than a beaker for volume measurements?

A graduated cylinder is designed for more precise measurements, while beakers are used for approximations.

What is the universal solvent?

water

What are the boiling points of water in Fahrenheit?

212°F

What is a hypothesis?

An educated guess or proposed explanation for an observation.

What is a control in an experiment?

The part of the experiment that does not change and is used for comparison.

What is a variable in an experiment?

The factor that is changed or tested in the experiment.

What is a base?

A substance that accepts H+ ions.

What is a buffer system?

A solution that resists changes in pH when acids or bases are added.

What is bromocresol purple?

A pH indicator that changes color based on the solution's acidity: yellow below pH 5.2, violet above pH 6.8.

What does Benedict’s reagent test for, and what is a positive result?

It tests for simple sugars. A positive result is a green to red-orange color change.

What does the iodine test detect, and what is a positive result?

It detects complex sugars (starch). A positive result is a blue-black color.

What does the Biuret test detect, and what is a positive result?

It detects proteins. A positive result is a purple color.

What does the Sudan test detect, and what is a positive result?

It detects lipids. A positive result is a red stain on filter paper.

What is dialysis tubing used for in experiments?

To simulate the selective permeability of biological membranes and demonstrate diffusion.

What happens to water in a hypertonic solution?

Water leaves the cell (or dialysis bag), causing it to shrink.

What happens to water in a hypotonic solution?

Water enters the cell (or dialysis bag), causing it to swell.

What happens to water in an isotonic solution?

Water enters and leaves the cell (or dialysis bag) at the same rate, maintaining equilibrium.

What is osmosis?

The movement of water across a semipermeable membrane from an area of lower solute concentration to higher solute concentration.

What is the function of the mortar and pestle?

To grind and crush substances into a fine powder.

What is the function of the choice chamber?

To test the preferences of small organisms in different environmental conditions.

What color does phenolphthalein turn in the presence of NaOH (a base)?

Pink.

What color does iodine turn in the presence of starch?

Blue-black

What did you observe when preparing a wet mount of onion cells?

The cell wall and nucleus.

What did you observe when preparing a wet mount of an elodea leaf?

Chloroplasts.

What is the significance of the letter "e" when viewed under the microscope?

It appears inverted under the microscope.

How do you use fine focus when viewing colored threads under the microscope?

To sharpen the image and bring different layers into focus.

What did you observe in a wet mount of yogurt?

Live bacteria.