Key Area 2.6

Question 1

Why are microorganisms ideal for research and industrial use

Answer 1

• Easy to cultivate
• rapid reproduction
• their food is cheap or a waste product
• their metabolism can be altered easily

Question 2

State 3 examples of culturing conditions that can be altered and state how they can be altered

Answer 2

PH - by buffers or addition of acids or alkalis

Oxygen levels - aeration (bubbling O2 through solution)

Temperature - outer jacket filled with water

Question 3

What materials do microbes need to grow

Answer 3

An energy source

Supply of raw materials

Question 4

Why are microorganism useful to humans

Answer 4

They make a wide range of metabolic products

E.g. Insulin

Question 5

Where would the culture of microorganism be used

Answer 5

Research and industry

Question 6

What are microbes grown on and why

Answer 6

Culture media, it supplies all essential nutrients

Question 7

Why must the culture environment be sterile

Answer 7

Avoid contamination from other microorganisms

Question 8

List 2 some aseptic techniques

Answer 8

• wash hands

* clean worktops

Question 9

Name 3 potential sources of energy for microbes being grown in a culture

Answer 9

• carbohydrates
• glucose
• light

Question 10

Name 2 raw materials microbes could use in a culture

Answer 10

• amino acids

* nucleotides

Question 11

Name and describe the different types of cell counts

Answer 11

• viable cell count - counting only living cells

* total cell count - counting the living and dead cells

Question 12

State the 4 phases of growth shown on a bacterial growth curve

Answer 12

Lag
Exponential
Stationary
Death

Question 13

Describe the lag phase

Answer 13

Where microorganisms adjust to the conditions of the culture

They produce enzymes that breakdown substrate

No cell division at the stage

Question 14

Describe the exponential phase

Answer 14

Rate of growth is at its highest at this stage

Question 15

Stationary phase

Answer 15

The culture medium becomes deleted and secondary metabolites are produced

The rate of production of new cells to equal to the death of old cells

Question 16

Describe the death phase

Answer 16

Lack of substrate and the toxic accumulation of metabolites causes death of cells

Death rate of cells is greater than the production rate

Question 17

What is the difference primary and secondary metabolites

Answer 17

Primary: related to the synthesis of cell materials (produced in exponential phase)

Secondary: no direct relationship to cell growth or synthesis of cell materials but may confer a evolutionary advantage (produced in stationary phase)

Question 18

State a secondary metabolites and it’s benefit to humans

Answer 18

Insulin

Helps treat diabetes

Question 19

What is the function of each of the following in a metabolic pathway:

1) precursors
2) inhibitor
3) inducer

Answer 19

1) large quantities of an earlier metabolite is supplied to ensure the continuous supply of another metabolite in a later stage
2) induces the formation of a key enzyme to ensure a continuous supply of a metabolite
3) reduces the inactivity it an enzyme to avoid the breakdown of a metabolite allowing it to accumulate

Question 20

Where do microorganism get their energy source and raw materials from

Answer 20

Growth medium