2.6 environmental control of metabolism

Question 1

State the different microorganisms

Answer 1

• bacteria
• archaea
• eukaryotes

Question 2

Why are microorganisms used

Answer 2

• high ability to adapt
• easy to cultivate
• fast growth speed

Question 3

State the 2 type of growth media

Answer 3

• solid

- liquid

Question 4

What do microorganisms have the ability to produce

Answer 4

• molecules required to generate products for systems

- (amino acids, vitamins, fatty acids)

Question 5

Give 2 examples of growth media (one of each state)

Answer 5

• broth (liquid)

- agar jelly (solid)

Question 6

State the 4 culture conditions

Answer 6

• sterility
• temperature
• pH
• oxygen levels

Question 7

Describe sterility

Answer 7

-reduces competition with other microorganisms for nutrients and reduces spoiling the product

Question 8

Describe temperature control

Answer 8

Optimum growth rate

Question 9

Describe oxygen levels

Answer 9

For respiration

Question 10

Describe pH

Answer 10

-use buffers to control how acid / alkaline the medium is

Question 11

State the 4 stages involved in the bacterial growth curve

Answer 11

• lag phase
• log phase
• stationary phase
• death phase

Question 12

Describe what happens to the trend of the graph during the lag phase

Answer 12

-there is little / no increase in cell number

Question 13

Describe what happens during the lag phase

Answer 13

Enzymes are induced to metabolise substrates

Question 14

Describe what happens to the trend of the graph during the log phase

Answer 14

-rapid growth due to plentiful nutrients

Question 15

Describe what happens during the log phase

Answer 15

-cells grow and multiply at the maximum rate providing that none of the factors are limited

Question 16

Describe what happens to the trend of the graph during the stationary phase

Answer 16

-the rate of production of new cells equals the rate of death

Question 17

Describe what happens during the stationary phase

Answer 17

• nutrients in the culture media begin to run out

- potential production of toxic metabolites

Question 18

Describe what happens to the trend of the graph in the death phase

Answer 18

-rate of cells dying exceeds the number of cells produced

Question 19

Describe what happens during the death phase

Answer 19

• cells die due to lack of nutrients in the culture

- toxic metabolites accumulate

Question 20

What type of graph is used to interpret the growth curves of micro organisms

Answer 20

Semi-logarithmic

Question 21

What is included in a viable cell count

Answer 21

-only the living microorganisms

Question 22

What is included in a total cell count

Answer 22

-the viable and dead cells

Question 23

What count shows the death phase

Answer 23

-viable