Harnessing Biology Flashcards
What is lactobacillus?
bacterial species used to make yoghurt
What is yeast?
unicellular fungi used to produce bread
What is the role of yeast in the production of bread?
respire anaerobically
- produce carbon dioxide which helps bread rise
What is the role of yeast in the production of beer?
respires anaerobically
- produces ethanol which is the alcohol in beer
What is the equation for anaerobic respiration in yeast?
glucose -> ethanol + carbon dioxide
What is the cell wall of yeast made of?
chitin
Describe an investigation for the role of anaerobic respiration in yeast in different conditions
- using hydrogen carbonate indicator
- add yeast to sugar solution to form a suspension
- add layer of oil
- connect this boiling tube to a second tube containing indicator using a delivery tube
- orange to yellow (incr. in CO2)
Describe the CORMMS plan for an investigation for the role of anaerobic respiration in yeast in different conditions
C - temp ; 30, 40, 50, 60, 70
O - yeast ; species, age, size
R - repeat each temp x3
M - volume of CO2
M - 5 mins
S - concentration/volume of sugar solution, pH
Why is the layer of oil necessary when investigating the role of anaerobic respiration in yeast in different conditions?
prevents oxygen from entering
means the yeast respires anaerobically
Why does the carbon dioxide level increase when investigating the role of anaerobic respiration in different conditions?
yeast are respiring anaerobically
producing carbon dioxide
What is another test for carbon dioxide?
limewater
clear to cloudy
What conditions can be changed when investigating the role of anaerobic respiration in different conditions?
temperature
conc of sugar
type of sugar
What is the role of lactobacillus in making yoghurt?
Describe the process of yoghurt production
- equipment sterilisation
- milk pasteurisation
- milk is homgenised
- cool the milk
- add live yog and mix
- pour into jars + cover
- incubate in warm
- yog is cooled
Why is the equipment used in yoghurt production sterilised?
kills unwanted bacteria and pathogens
What temperature is the equipment heated to in sterilisation?
95
Why is the milk pasteurised in yoghurt production?
kills unwanted bacteria and pathogens
What temperature is the milk heated to in pasteurisation?
85-95
Why is the milk homogenised in yoghurt production?
disperse any fat gobules
Why is the milk cooled in yoghurt production directly after the lactobacillus has been added?
so the bacteria lactobacillus does not denature due to high temperatures
What temperature is the milk cooled to in yoghurt production directly after the lactobacillus has been added?
40-45
How does the yoghurt thicken in yoghurt production?
lactobacillus digests milk proteins
respire anaerobically - produce lactic acid
lactic acid has a low pH
causes milk proteins to break down
COAGULATION - thickens
What is the thickening of the yoghurt caused by?
break down of milk proteins by lactobacillus which produces lactic acid with low pH
What is the thickening of yoghurt called?
coagulation
Why is the yoghurt cooled to 5?
serving
slows enzyme activity
What does the lactobacillus ferment lactose into?
lactic acid
What must farmers make on their farms?
profit
How do farmers maximise profit on farms?
control environment to increase yield
Why are greenhouses preferable over fields?
easy to control factors
List factors of greenhouse
- artificial heating
- artificial lighting
- co2
- watering
What do greenhouses and polythene tunnels provide?
enhanced conditions
What are greenhouses and polythene tunnels made of?
transparent material
How does the transparent material enhance conditions?
allows sufficient natural light
How does additional lighting enhance conditions?
provides ‘longer day’ in winter
How does greenhouse effect enhance conditions?
raises temperature
How does burning of fossil fuels or wood enhance conditions?
raises temperature and produces co2 and water vapour
How does added water vapour enhance conditions?
maintains moist atmosphere and reduces water loss by transpiration
How do fertilisers increase growth?
provide elements for plants
What is magnesium used for?
chlorophyll
What are nitrates used for?
proteins