unit 2 KA6 - environmental control of metabolism

Question 1

what are classed as microorganisms

Answer 1

archae, bacteria, and some species of eukaryotes

Question 2

true or false: microorganisms use a wide variety of substrates for metabolism and produce a range of products from their metabolic pathways

Answer 2

true

Question 3

why are microorganisms used

Answer 3

because of their adaptability, ease of cultivation and speed of growth

Question 4

what are examples of the complex molecules required for biosynthesis that many micro-organisms produce

Answer 4

amino acids, vitamins and fatty acids.

Question 5

not all micro-organisms can produce all of the complex molecules required for biosynethesis. how do the other micro-organisms that cannot get these complex molecules?

Answer 5

they require these to be supplied through the growth media

Question 6

when culturing micro-organisms, what does their growth media require?

Answer 6

• the raw materials for biosynthesis

- an energy source

Question 7

how is the energy source that growth media requires derived?

Answer 7

either from chemical substrates or from light in photosynthetic micro-organisms

Question 8

what are the culture conditions

Answer 8

• control of temperature
• sterility
• oxygen levels
• pH

Question 9

why are sterile conditions important when culturing micro-organisms

Answer 9

they reduce competition with desired micro-organisms for nutrients and reduce the risk of spoilage of the product

Question 10

what are the phases of growth

Answer 10

• lag
• exponential
• stationary
• death

Question 11

what happens in the lag phase of growth

Answer 11

this is where the enzymes are induced to metabolise substrates

Question 12

what happens in the exponential growth phase

Answer 12

this is the phase that contains the most rapid growth of micro-organisms due to plentiful nutrients

Question 13

what happens in the stationary growth phase

Answer 13

this occurs due to the nutrients in the culture media becoming depleted as well as the production of toxic metabolites. secondary metabolites are also produced, such as antibiotics. in the wild, these metabolites confer an ecological advantage by allowing the microorganisms which produce them to outcompete other microorganisms

Question 14

what happens in the death phase of growth

Answer 14

this occurs due to the toxic accumulation of metabolites or the lack of nutrients in the culture

Question 15

what does the course specification say about growth curves of microorganisms because for the life of me idk how to make it a question

Answer 15

use of semi-logarithmic scales in producing or interpreting growth curves of micro-organisms

Question 16

what do viable cell counts involve

Answer 16

they involve counting only the living micro-organisms

Question 17

what do total cell counts involve

Answer 17

they involve counting only viable and dead cells

Question 18

which cell counts show the death phase

Answer 18

only the viable cell counts show the death phase where cell numbers are decreasing.