Microbiology

Question 1

flagellum function

Answer 1

for motility

Question 2

pili

Answer 2

for attaching to surfaces and transferring plasmids by conjugation

Question 3

plasmid

Answer 3

circular DNA which contains extra bacterial genes including genes for antibiotic resistance

Question 4

where is the circular DNAs of prokaryotes found

Answer 4

in the nucleoid

Question 5

by which process do prokaryotes reproduce

Answer 5

binary fission

Question 6

the main function of the cell wall
other functions of the cell wall

Answer 6

*To prevent osmotic lysis
it supports the structure of the cell and provides rigidity to the cell
provides pressure inside the cell

Question 7

what is a bacterial cell wall made of

Answer 7

peptidoglycan

Question 8

what antibiotic is used instead of penicillin to combat gram-negative bacteria

Answer 8

vancomycin

Question 9

physical requirements in which microbes thrive

Answer 9

optimal ph
optimal temperature
aerobic environments for some microbes

Question 10

the optimal temperature for pathogens to grow(mesophiles)

Answer 10

37 degrees

Question 11

at what temperature should bacteria be incubated, and for how long?

Answer 11

at 25 degrees and between 24-48 hours

Question 12

which do we not completely seal the plate containing

Answer 12

to allow oxygen into the plate

Question 13

why do we incubate bacteria at 25 degrees, and not completely seal the plate containing bacteria?

Answer 13

to ensure that the growth of pathogenic bacteria is low, as bacteria tend to grow rapidly at body temperature (37 degrees) and in anaerobic conditions

Question 14

obligate aerobes

Answer 14

bacteria that require oxygen to replicate

Question 15

obligate anaerobes

Answer 15

bacteria that can only survive and replicate in the absence of oxygen

Question 16

facultative anaerobes

Answer 16

bacteria that are able to survive in the absence of oxygen but grow and divide faster in the presence of oxygen

Question 17

in which two mediums can bacteria be grown

Answer 17

on liquid media like broth
on solid media containing agar

Question 18

bacterium growth media usually contain a carbon source and a nitrogen source. true or false

Answer 18

true

Question 19

in which form is the carbon source in a media usually in

Answer 19

in the form of glucose

Question 20

the purposes of aseptic techniques

Answer 20

to prevent contamination of the environment by the microbes being handled

to prevent contamination of the microbial cultures by unwanted microbes from the environment

Question 21

what are the purposes of the following aseptic techniques
1. Autoclaving all glassware at 121 degrees for 15 minutes
2. flaming loops and wires until red hot.
3. opening the petri dish lids at a small angle
4. roaring blue flame
5. keeping McCartney caps in hand and flaming the neck of the bottle

Answer 21

1. kill bacteria and spores
2. To kill bacteria
3. to prevent bacteria from entering the dish
4. to create a convection current to uplift air away from the cultures
5. to not contaminate the desk and also to create a convection current to lift air from the broth

Question 22

purpose of sterilizing materials during experiments

Answer 22

to grow pure cultures of microorganisms

Question 23

how do we sterilize plastics like Petri dishes

Answer 23

by irradiating them

Question 24

how do we sterilize the growth media

Answer 24

by heating it in an autoclave

Question 25

autoclave

Answer 25

a pressure cooker that allows a pressure of 15 atm and a temperature of 121 degrees to be generated

Question 26

the function of streak plates

Answer 26

can be used to separate mixed cultures into pure ones by separating out individual colonies which can then be used to inoculate fresh plates

Question 27

to inoculate means

Answer 27

to introduce cells or organisms into a culture medium

Question 28

state three problems encountered when trying to count bacteria(what are the solutions to these problems)

Answer 28

they are small (use a microscope or spread them onto agar and allow them to grow into a colony)
they are several of them (Dilute the sample)
it is difficult to determine whether they are alive or dead (allow them to grow into colonies)