2.6 Environmental Control of Metabolism

Question 1

3 domains of life

Answer 1

• archaea
• bacteria
• some eukaryotes

Question 2

of the 3 domains of life, microorganisms can belong to..

Answer 2

all 3

Question 3

microorganisms use … for metabolism and produce …

Answer 3

a wide variety of substrates and produce a range of products

Question 4

microorganisms are used in industries because (3)

Answer 4

• ease of cultivation
• speed of growth
• adaptability

Question 5

to be cultured, microorganisms must be provided with what? (2)

Answer 5

• appropriate growth medium
• carefully controlled environmental factors

Question 6

growth media

Answer 6

the substance that microorganisms are grown on

Question 7

what does growth media contain?

Answer 7

• raw materials
• an energy source

Question 8

examples of complex molecules required by microorganisms (3)

Answer 8

• amino acids
• vitamins
• fatty acids

Question 9

energy sources (2)

Answer 9

• chemical substrates
• light (in photosynthetic organisms)

Question 10

conditions that have to be controlled when culturing (4)

Answer 10

• sterility
• temperature
• oxygen levels
• pH

Question 11

why are sterile conditions required when culturing? (2)

Answer 11

• reduces competition for nutrients with the desired microorganism
• reduces risk of spoilage

Question 12

phases of microorganism growth (4)

Answer 12

• Lag
• Log (exponential)
• Stationary
• Death

Question 13

Lag phase

Answer 13

enzymes are induced to metabolise substrates

Question 14

log/exponential phase

Answer 14

most rapid phase of growth due to plentiful nutrients

Question 15

stationary phase

Answer 15

• nutrients in growth media become depleted
• there is s build up of toxic metabolites
• secondary metabolites produced

Question 16

secondary metabolites

Answer 16

in the wild, they provide an ecological advantage as they allow the microorganism which produces them to outcompete others

Question 17

in what stage are secondary metabolites produced?

Answer 17

stationary

Question 18

example of a secondary metabolite

Answer 18

antibodies

Question 19

death phase

Answer 19

occurs because of toxic accumulation of metabolites and a lack of nutrients

Question 20

viable cell count

Answer 20

only count the living microorganisms

Question 21

total cell count

Answer 21

count both living and dead microorganisms

Question 22

which type of cell counts shows the death phase and why?

Answer 22

viable cell count, as viable cell numbers are decreasing