Unit 4.1.1.6 Triple Culturing Microorganisms

Question 1

What are bacteria grown in?

Answer 1

culture medium

Question 2

What does the culture medium contain?

Answer 2

carbohydrates, minerals, proteins, vitamins

Question 3

What are bacteria grown on?

Answer 3

agar plates

Question 4

Bacteria grow on the agar plate and form visible…

Answer 4

colonies

Question 5

Agar plates are incubated at what temperature?

Answer 5

25 degrees

Question 6

In industrial conditions agar plates are incubated at higher temperatures because

Answer 6

they can grow faster

Question 7

Why are schools not allowed to incubate plates at high temperatures?

Answer 7

encourages growth of harmful microorganisms

Question 8

Name substances that can kill bacteria

Answer 8

antiseptics, antibiotics

Question 9

When growing bacteria on agar plates, discs of antibiotic can be added. What is the area around the disc called where no bacteria is growing?

Answer 9

zone of inhibition

Question 10

Discs soaked in antibiotic and placed on the agar plate, enter the plate by what process?

Answer 10

diffusion

Question 11

Which bacteria are NOT killed by the antibiotic?

Answer 11

antibiotic resistant bacteria

Question 12

When investigating bacterial growth with different antibiotics what should the control disc contain?

Answer 12

disc soaked in water

Question 13

When investigating bacterial growth why is a control important?

Answer 13

to be sure that any difference in growth is due to the antibiotic only

Question 14

bacteria reproduce by what process

Answer 14

binary fission

Question 15

How can you prevent unwanted microorganisms from growing on your agar plate?

Answer 15

use sterile petri dishes sterilise the inoculating loop sterilise the culture medium before adding your bacteria tape the lid on

Question 16

What is the purpose of taping the agar lid on?

Answer 16

to prevent unwanted microorganisms from entering

Question 17

How do you sterilise an inoculating loop?

Answer 17

pass it through a hot flame

Question 18

what does sterilise mean?

Answer 18

to kill unwanted microorganisms

Question 19

An example of a prokaryotic cell is

Answer 19

bacteria

Question 20

What happens to the bacterial cell when it divides by binary fission

Answer 20

it splits into 2

Question 21

A bacterial cell has a mean division time of 30 minutes. How many cells will there be after 2.5h?

Answer 21

5 divisions 2 to the power 5 = 32 cells

Question 22

What is the mean division time of a bacterial cell?

Answer 22

the time it takes to divide into 2

Question 23

What conditions are required for bacterial growth?

Answer 23

warmth, oxygen, moisture and an energy source (carbohydrates)

Question 24

How is bacterial DNA different to animal cell DNA?

Answer 24

bacterial cells have.. No nucleus free floating in cytoplasm circular portions called plasmids

Question 25

Why do you store agar plates in an incubator upside down?

Answer 25

to prevent condensation landing on the bacterial lawn and disturbing it

Question 26

How can you tell which antibiotic disc is the most effective?

Answer 26

It has a bigger zone of inhibition

Question 27

How do you calculate the area of the zone of inhibition?

Answer 27

use the formula for area of a circle (pie r squared)

Question 28

What process is this diagram representing?

Answer 28

Binary fission