Harnessing biology Flashcards
How is yoghurt made?
Milk is pasteurised then cooled
Bacteria called lactobacillus bulgaricus is added
The mixture is kept at 46°C
What is lactobacillus used for when making yoghurt?
It respires anaerobically producing lactic acid. This lowers the pH, acting as a preservative.
The acid also coagulates the milk protein, giving yoghurt its texture
Explain the function of the temperature monitor and cooling jacket in a fermenter.
Temp monitor makes sure temp stays at right point, if it gets too high, cooling jacket removes heat energy by surrounding fermenter in cool water so enzymes don’t denature
Why is air needed in the fermenter?
maintains a sterile condition, gives oxygen for respiration
Why is air filtered before going into the fermenter?
no bacteria, prevents contamination
Why are viruses considered not living organisms?
do not respire
Why is the super heated steam used in a fermenter?
kills unwanted micro-organisms. Leaves only water with no other residue.
Makes aseptic conditions
Pros of organic fertilisers
Cheap or no cost (contain faeces and straw)
range of minerals
Pros of inorganic fertilisers
contents, specific concentration known
fast acting
Cons of organic fertilisers
difficult to apply
slow release
may contain pests
cons of inorganic fertilisers
expensive
may cause eutrophication
can damage soil structure
What are pests?
organisms which reduce the yield of an organism
How can you control pests?
Biological control
Pesticides (chemicals which kill pests)
Explain sewage eutrophication
sewage leaches into water
bacteria multiply
increase biological oxygen demand
decrease in oxygen, causing death to aquatic life
disease -> pathogenic bacteria
Greenhouse gases:
Methane
CO2
Nitrous oxide
Water vapour
