Laboratory Techniques module quiz: micropipetting, dilutions, plating and bioreactors (SEAB O-Level Applied Subject) quiz

To avoid carry-over that would contaminate the sample or ruin a dilution

To make the pipette lighter

Because tips wear out after one use mechanically

To change the volume setting

Press only to the first stop

Not press the plunger at all

Press past the first stop to the second stop

Shake the pipette vigorously

concentration = amount of solute x volume

concentration = volume ÷ amount of solute

concentration = amount of solute + volume

concentration = amount of solute ÷ volume of solution

Two-fold

Ten-fold

Nine-fold

One hundred-fold

1000

30

100

3

1000 times higher

Exactly the same

1000 times lower

10 times lower

4 cells per mL

40 cells per mL

4000 cells per mL

400 cells per mL

400 000

400

4000

40 000

To spread the cells evenly for counting

To kill the bacteria

To progressively thin the cells so single, separated colonies grow

To dissolve the agar

It kills exactly half the cells

It always gives a single colony

It removes the need for agar

It distributes a measured volume evenly so the colonies can be counted

Reading the sequence of DNA

Growing microorganisms or cells under controlled conditions for large-scale production

Separating DNA fragments by size

Storing samples at minus 80 degrees Celsius

Temperature, pH, oxygen supply and nutrient levels, while staying sterile

Only the colour of the medium

Only the height of the vessel

Only the brand of the steel

To make the product taste better

To slow the wanted microorganism down

To stop contaminating microorganisms from outgrowing the culture and spoiling the product

Because sterile vessels are cheaper to buy

It increases the number of cells so they are easier to see

It reduces a dense culture to a countable number of colonies on the plate

It changes the cells into a different species

It removes the need to use agar