use of biological resources (only in mock) Flashcards
where does anaerobic respiration happin
in plant cells, animals and some microorganisms - such as yeast!
when is anaerobic respiration in yeast used
during beer brewing and bread- making
what is the anaerobic respiration word equation
glucose –> ethanol + carbon dioxide
what is ethanol
the alcohol found in alcoholic drinks like beer and wine
what happens in bread making
bubbles of carbon dioxide gas expand though the dough and help the bread rise
the high temperature used in bread making mean that the ethanol does not remain in the bread after cooking had finished - it has evaporated
what is a way to investigate anaerobic respiration in yeast
study the production of carbon dioxide under different conditions
what colour does limewater turn in the presence of carbon dioxide
cloudy white / milky
what colour does hydrogen carbonate indicator turn in the presence of carbon dioxide
changes from orange to yellow
what is the method of investigating anaerobic respiration in yeast
1- dissolve sugar in previously boiled water
2- add yeast and mix to form a suspension and pour into a boiling tube
3- add a layer of vegetable oil
4- connect a delivery tube to a second boiling tueb, this time containing limewater or hydrogen carbonate indicator
what bacteria is used for yoghurt production
Lactobacillus (bulgaricus)
explain the process of yoghurt making
- milk is pasteurised (heated) to kill bacteria
- after it has cooled, Lactobacillus is added and the mixture is maintained at 46 degrees - ensures the bacteria’s enzymes are not denatured
- lactobacillus respires anaerobically producing lactic acid which lowers the pH acting as a preservative.
- the acid also coagulates the milk protein, as the acidic conditions change the shape of the proteins giving yoghurt its texture and flavour
- the yoghurt is further cooled to 5 degrees to help preserve the yoghurt
