2.6

Question 1

Why use microorganisms?

Answer 1

Microorganisms area highly adaptable given the variety of niches they can inhabit - can make use of a wide variety of substrates for metabolism and produce a range of products from their metabolic pathways

Question 2

Are microorganisms easy to cultivate?

Answer 2

Yes

Question 3

What type of growth speed do microorganisms have?

Answer 3

Rapid

Question 4

What energy source do microorganisms require?

Answer 4

Chemical or Light + Raw materials from simple chemical compounds for biosynthesis

Question 5

What are the types of growth media?

Answer 5

Small scale - agar jelly, broth

Large scale - industrial fermenters

Question 6

Do microorganisms require complex molecules such as amino acids, vitamins and fatty acids.

Answer 6

Many can produce these themselves but others require them to be supplied in the growth media

Question 7

What does the use of aseptic techniques do?

Answer 7

Maintains sterile conditions - avoided contamination therefore reduces competition from other microbes

Question 8

What does the use of computer-monitoring and control do?

Answer 8

Maintains temperature, pH and oxygen levels at optimum

Question 9

What is the viable cell count?

Answer 9

Counts only living microorganisms

Question 10

What is the total cell count?

Answer 10

Counts viable and dead cells

Question 11

What happens during the lag phase?

Answer 11

Little or no increase in cell number.
Microorganisms adjust to the conditions of the culture and begin to metabolise substrate (may need to endure enzymes) - cells prepare for division

Question 12

What happens during the exponential (logarithmic) phase?

Answer 12

Contains the mos rapid growth of microorganisms due to plentiful nutrients.

Question 13

What happens during the stationary phase?

Answer 13

Cell production and death are equal and so population remains steady.
The nutrients in the culture medium become depleted and toxic metabolites are produced.
Secondary metabolites (e.g. antibiotics) are also produced.
In the wild these metabolites confer an ecological advantage by allowing the microorganisms which produce them to outcompete other microorganisms

Question 14

What happens during the death phase?

Answer 14

There is a lack of nutrients and/or oxygen and the toxic accumulation of metabolites increase - the death rate and population falls.