Chapter Six

Question 1

The optimum pH for MOST bacteria is near..

Answer 1

7

Question 2

A psychrophile has an optimal growth temperature of about…

Answer 2

15 degrees C

Question 3

Organisms that require high salt concentrations for growth are called….

Answer 3

obligate halophiles

Question 4

What is/are the energy source utilized by primary producers in the hydrothermal vents on the ocean floor?

Answer 4

hydrogen sulfide

Question 5

Addition of sats preserves foods because they..

Answer 5

increase osmotic pressure

Question 6

Chemoautotrophs and photoautotrophs derive their carbon form…

Answer 6

carbon dioxide

Question 7

Some microorganisms use gaseous nitrogen directly from the atmosphere in a process called..

Answer 7

nitrogen fixation

Question 8

An organism that uses oxygen when present but can grow without oxygen is called a(n)…

Answer 8

facultative anaerobe

Question 9

Which organism is killed by atmospheric oxygen?

Answer 9

obligate anaerobe

Question 10

Toxic hydrogen peroxide in some bacteria can be broken down into water and oxygen by the enzyme

Answer 10

catalase

Question 11

Generation time can best be defined as

Answer 11

the time it takes for a cell to divide

Question 12

Bacterial growth is usually graphed using what kind of scales?

Answer 12

logarithmic (semi-logarithmic)

Question 13

In which growth phase is there intense activity preparing for population growth, but no increase in population?

Answer 13

lag phase

Question 14

Which of the following is NOT a possible reason why exponential growth stops?

Answer 14

bacteria becoming dormant

Question 15

What happens in the stationary phase?

Answer 15

the number of microbial death is equal to the number of new cells formed

Question 16

Which type of medium suppresses the growth of unwanted bacteria and encourages growth of desired microbes?

Answer 16

selective media

Question 17

Microbes that are introduced into a culture medium to initiate growth are called a(n)..

Answer 17

inoculum

Question 18

What is added to a medium when it is desirable to grow bacteria on a solid medium?

Answer 18

agar

Question 19

A culture medium made of extracts from yeasts, meat, or plants is a ____ medium.

Answer 19

complex

Question 20

A spectrophotometer can be used to measure…

Answer 20

turbidity

Question 21

The method in which a measured volume of bacterial suspension is placed within a defined area on a microscope slide is called the..

Answer 21

direct microscope count

Question 22

Which process is used to ensure that plates contain 30 to 300 colonies when counted?

Answer 22

serial dilution

Question 23

Which is the best technique to use to measure the growth of filamentous organisms?

Answer 23

dry weight

Question 24

Starting with one bacterial cell, how many cells would you have after 10 generations?

Answer 24

1024