Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Ch 6
Ch 6 Review Questions
| Question | Answer |
|---|---|
| For microbes, growth is an increase in ___, but not ____. | # of cells; not cell size |
| when bacteria are grown on a plate of agar, what is the name of the group of cells that form a visible clump and are all descendants of one microbe? | colony |
| What are some of the physical requirements to consider before attempting to grow microbes? | temp, pH, osmotic pressure |
| Which tye of microbe grows best between 0 degrees Celsius - 25C, and often causes food spoilage | Psytotrophs |
| In the food service industry, what is the Danger Zone? | 15-55C |
| Why is the above item called the Danger Zone? | rapid bacterial growth and possible toxin production |
| Why is a hypertonc environment helpful in controlling bacterial growth? | The growth of the cell is inhibited as the plasma membrane pulls away froom the cell wall. The addition of salts and increase in osmotic pressure can be used to preserve foods. |
| In a food item, how could one create a hypertonic environment? | adding salt or sugar; dehydrating |
| What is a halophile? Examples? | Can tolerate high salt concentrations; Extreme halophiles: adapted well to high salt concentrations; obligate halophiles; facultative halophiles: do not require high salt concentrations |
| Plasmolysis occurs when a cell is placed in a/an____ | hypertonic environment |
| What do microbes need a carbon source for? | required for final electron acceptor; zero O2 equals death |
| What do microbes need nitrogen for? | A necessary component of amino acids which are the building blocks of proteins |
| What do microbes need sulfur for? | Vital for all living organisms; component of some vitamins, amino acids, and RNA |
| Name 3 different methods microbes use to obtain nitrogen. | Most bacteria decompose proteins; some bacteria use NH4+ or NO3-; few use N2 in nitrogen fixation |
| What do microbes need PO4 for? | Essential component of ATP. DNA, RNA, and membrane phospholipies. |
| For microbes that require oxygen, why do they need it? What do they use it for? | Obligate aerobes require it for final electron acceptor. Die w/o it. Facultative aerobes make ATP by aerobic resp if O2 is present; Microaerophiles require small amts |
| What is the difference between a microaerophile and an obligate aerobe? | Microaerophile requires O2; obligate aerobe would die without O2 |
| Which organisms don't use O2 for growth, but tolerate it well. | aerotreatment |
| What type of organism grows best where oxygen is present, but can growth in lower amts of oxygen if it is depleted? | facultative aerobes |
| Where does agar come from? | seaweed |
| At what temp does agar liquify? | 100C |
| At what temp does agar solidify? | 40C |
| What is nutrient agar? | a complex media |
| A liquid bacterial growth medium is called | broth |
| Bacterial growh media that is designed to grow some organisms and discourage the growth of others is called | selective media |
| What are some examples of the type of media in selective media? | sulfite, dextrose, manitol salts |
| Bacterial growth media that is designed to grow a variety of organisms, but allows the microbiologist to see the difference between them is called | differential media |
| What is the theory behind the candle jar? | Candle consumes sme O2 and releases in CO2 as it burns |
| What is a capnophile? | Microbes that require high CO2 conditions |
| What is an enrichment media and what is it used for? | blood agar, chocolae agar; encourages growh of desired microbe |
| what is a fastidious organism? | organism that's hard to grow |
| What is the purpose of the streak plate? | isolate pure cultures |
| During which growth phase do most antibiotics work the best? | Log |
| If given a beginning and ending number of microbes and the time elapsed, how do you calculate the generation time? | G=t/n |
| What is generation time? | The amt of time it takes for population to double |
| During which phase of bacterial growth when cellular reproduction is at its highest? | Lag |
| What is a CFU? | colony forming units |
| What is the name of the special slide used when doing a direct microscope count of microbes? | Petroff-Hausser cell counter |
| Which indirect method of measuring numbers of bacteria uses a spectrophotometer and measures turbidity? | metabolic activity |
| What is turbidity? | practical way of monitoring bacterial growth |
| What is a biofilm? |
Created by:
resa722
Popular Biology sets