Microbiology Lab Experiments- Exercise 20 Flashcards


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Determination of a bacterial growth curve: The role of temperature
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1

The effect of temperature can be determined by measuring the _________________________.

population growth rate

2

When they speak of "air" as a growth requirement what do they mean?

they are referring to the oxygen in air

3

When they refer to oxygen they mean _______________.

molecular oxygen that acts as an electron acceptor in aerobic respiration.

4
card image

What is the an image of?

bacterial growth rate

5

During log phase the cells are growing at ____________________________.

Fastest rate possible under the conditions provided

6

What is generation or doubling time?

The time it takes for one cell to divide into 2 cells or the time required for the population of cells to double.

7

The shorter the generation time the ___________ the growth.

faster

8

Turbidity can be measured with a ______________.

spectrophotometer to determine growth

9

True or false. Although turbidity is not a direct measure of bacterial numbers, increasing turbidity does indicate growth.

true

10

Changes in the logarithmic absorbance scale on the spectrophotometer correspond to changes in ______________________________.

The number of cells

11

A growth curve can be obtained by graphing absorbance (Y-axis)vs. time (X-axis). The rate of growth is indicated by the ____________ of the lines, faster growth produces a steeper (higher number) slope.

slope

12

What is the minimum growth temperature?

the lowest temperature at which a species will grow

13

A species grows fastest at its ___________________?

optimum growth temperature

14

The highest temperature at which a species will grow is its ____________________________.

maximum growth temperature

15

At temperatures near the maximum growth temperature, growth ceases, presumably because of the ______________________________.

denaturation of enzymes

16

Increasing temperature optimizes or lowers the growth of the bacteria?

lowers

17

At what temperature would you expect E-coli to grow best?

35 degrees Celsius

18

Define the optimal growth temperature for each of the following classes of bacteria...

hyperthermophile 80 and above, Thermophile between 50 and 80. Mesophile between 20 and 50. Psychrophile -5 to 20.

19

What is the optimum growth temperature for most human pathogens?

37* is the optimum temperature for most pathogens because that is human body temperature.