Microbiology-LAB EXAM

Ubiquity of Microorganisms

100

What is ubiquity?

the existence of something(microorganisms) everywhere at the same time.

200

Name the two different temperatures.

Room Temperature: about 25 degrees celsius

Body Temperature: about 37 degrees celsius

300

Name the types of organisms.

Fungi (molds)- large & fluffy

Ex: found on spoiled bread

Bacterial- soft & glistening, usually cream or yellow

400

What's the name of the instrument for placing the tubes?

Incubator

500

What is agar?

Carbohydrate derived from seaweed used to solidify a liquid medium

Microscope

100

Why is oil immersion used?

Oil immersion prevents the light from scattering and prevents damage from the lens/ breaking slides.

200

Name two types of paper used.

Lens: lens cleansing paper

Stage: paper towel

300

What are the magnifications and when is each used?

4X

10X (ocular)

40X (high dry)

100X (oil immersion)

400

How is the microscope cleansed?

use lens paper and lens cleaner. Any other paper will scratch the optical glass.

500

Name the parts of the microscope & their functions.

Microscope: used to magnify & see smaller things

Ocular(eyepiece): (10X) used to see the image

Course adjustment: moves stage up/down & used to focus the image 

Fine adjustment: makes image sharp

Aseptic Techniques

100

Explain aseptic technique.

method of handling microbes & materials in a way to minimize contamination.

200

Define inoculation.

the process of transferring a microbe from one medium to the next.

300

Define inoculum. 

sample being transferred. 

400

Name the inoculating instruments.

Inoculating loop:

Inoculating needle:

Microincinerator

500

Explain the importance the Petri dish lid.

Lift the Petri dish lid at about a 45 degree angle. DO NOT completely remove the lid. Used to shield the plate from airborne contaminants.

Isolation Streak Plate

100

What is the purpose of the streak?

Isolates single colonies because mixed populations can form.

200

What is the isolation streak plate?

method used to separate individual bacteria from mixtures

300

How does a successful streak plate look?

Able to see individual bacteria 

1st streak area: heavy growth

2nd streak area: growth starting to thin out and individual colonies are slowing appearing

3rd streak area: thinner growth & isolated colonies 

400

How does an unsuccessful streak plate look and what could've went wrong?

Plates without individual isolated colonies and no growth seen.

No or poor flaming & improper pattern

500

What are the steps in streaking a plate?

1. Flame your loop & dip into the unknown mixture. Parallel/ close together & 1st streak area should cover about half of the plate

2. Flame loop & dip into unknown mixture again. Drag loop across one side of streak area. 2nd streak area should cover about a quarter and try not to cross back into 1st streak area.

3. DO NOT flame loop before streaking 3rd area. Do not cross back into previous areas & cover quarter of the plate

Simple Straining

100

Explain the purpose of simple staining.

observe the morphology/shape & the arrangement of cells

200

Name the 2 types of stains used. 

Methylene Blue & Safranin 

300

Why are charges negative?

because of the presence of peptidoglycan- the structural backbone of the bacterial cell wall

400

What are the most three common shapes of bacteria?

Bacillus (oblong, rod)

Coccus (sphere)

Spirillum (comma-shaped spiral)

500

What are the two types of organisms used?

Bacillus cereus

Staphylococcus aureus