harnessing biology Flashcards
1
Q
equation for anaerobic respiration in yeast
A
glucose -> carbon dioxide + ethanol
2
Q
what does yellow show in hydrogen carbonate indicator
A
increasing CO2 in indicator (high rate of respiration)
3
Q
what does red show in hydrogen carbonate indicator
A
atmospheric level of CO2
4
Q
what does purple show in hydrogen carbonate indicator
A
decreasing CO2 in indicator (high rate of photosynthesis)
5
Q
products of yeast respiring aerobically
A
carbon dioxide + water
6
Q
when bread gets baked in the oven, what 3 things happen?
A
- gas bubbles expand, giving bread its light texture
- baking kills yeast cells
- ethanol from fermenters evaporates
7
Q
method to investigate the effect of temp on respiration with yeast
A
- changing temp from 20 degrees - 90 degrees
- organism used is the same species of yeast
- repeat 3x for each temp and find mean
- measure volume of CO2 produced
- measure after 5 mins
- same volume of glucose
- same volume of yeast
8
Q
making yoghurt method:
A
- sterilise any equipment to kill off unwanted bacteria
prevents contamination -> prevents competition between bacteria - milk is pasteurised at 85 degrees for 10-30 mins -> can kill any natural bacteria the milk contains
- milk is homogenised -> disperses fat into globules (makes smaller) so they don’t sink to bottom
- milk is cooled to 30-40 degrees -> stops the bacteria being killed
is inoculated with lactobacillus bacteria -> digest milk proteins and ferment the lactose producing lactic acid
mixture is incubated at this temp for 3-12 hours - during fermentation the proteins in milk denature - this is due to a drop in the pH, resulting in the mixture coagulating (thickening)
thickened yoghurt is stirred and cooled to 5 degrees -> halts action of lactobacillus - flavourings colourants and fruits are added before packaging
9
Q
give benefits of adding fruit to the yoghurt:
A
- adding fruit is a natural sweetener
-> no excess sugar - fruit has vit C -> prevents scurvy
- fibre in fruit skin
