use of biological resources

Question 1

what kingdom is yeast found in?

Answer 1

fungi- specific unicellular fungi

Question 2

what fungus produces the antibiotic penicillin?

Answer 2

penicillium

Question 3

what else do fungi/bacteria make that is useful for humans?

Answer 3

human insulin

Question 4

what are the five components of an industrial fermentor?

Answer 4

cooling jacket, air filter, stirrers, growth medium, super-heated steam

Question 5

what is the purpose of the cooling jacket?

Answer 5

to remove heat energy, to stop the fermentor from overheating and enzymes denaturing

Question 6

what is the purpose of the air filter?

Answer 6

to filter air coming in, to maintain sterile conditions

Question 7

what is the purpose of the stirrers?

Answer 7

to keep the broth well stirred to move oxygen, nutrients and microbes around. To also distribute heat evenly.

Question 8

what is the purpose of the growth medium?

Answer 8

to contain all necessary glucose and amino acids for micro-organisms growth

Question 9

what is the purpose of the super-heated steam?

Answer 9

this is to be applied before the fermentor is used, to kill any unwanted micro-organisms. only leaves water with no other residue.

Question 10

what type of respiration is used during beer brewing and bread making?

Answer 10

anaerobic respiration

Question 11

what is the word equation for anaerobic respiration in yeast?

Answer 11

glucose-> carbon dioxide + ethanol

Question 12

what does the yeast use in the bread to respire?

Answer 12

sugar

Question 13

what helps the bread rise and expand the dough during bread making?

Answer 13

bubbles of carbon dioxide

Question 14

why does ethanol not remain in the bread after cooking?

Answer 14

the high temperatures used during cooking mean that the ethanol evaporates during cooking and doesn’t remain in the bread

Question 15

describe the steps of the anaerobic respiration experiment?

Answer 15

1-place sugar and add yeast to make a solution, mix to form a suspension, and pour into a boiling tube
3- add a layer of oil on top
4- place in water bath
5- connect a delivery tube to an inverted measuring cylinder and place in a trough of water
6-

Question 16

why do we place a layer of oil on top of the yeast and sugar solution?

Answer 16

to prevent oxygen entering, whilst allowing carbon dioxide to leave. this ensures its anaerobic.

Question 17

describe and explain the trend between increasing temperature and volume of carbon dioxide produced?

Answer 17

as temp increases so does the volume of carbon dioxide. this is because the enzymes have more kinetic energy leading to more successful collisions between the active site and substrate and leads to more gas produced.

Question 18

why does the volume of gas start to decreases as temp increases?

Answer 18

as the enzymes have gone past their optimum point and have now denatured. this means the active site has changed shape so the substrate no longer fits. this therefore decreases the volume of carbon dioxide produced.

Question 19

how could we increase the validity of this investigation?

Answer 19

use a gas syringe- more accurate for measuring volume of carbon dioxide
use thermostatically controlled water bath- as maintains the correct temp
repeats- 3x and take an average

Question 20

what is step 1 of the yoghurt making process?

Answer 20

milk is pasteurised to 85-95*c.

Question 21

why does this occur?

Answer 21

to kill any harmful micro-organisms or those that may turn it into curds and whey

Question 22

what is step 2 of the yoghurt making process?

Answer 22

the milk is homogenised

Question 23

why does this occur?

Answer 23

to disperse any globules of fa

Question 24

what is step 3 of the yoghurt making process?

Answer 24

the milk is cooled to 40-45*c

Question 25

why does this occur?

Answer 25

so it can be inoculated with the starter of lactobacillus bacteria without being denatured by high temperatures

Question 26

what is step 4 of the yoghurt making process?

Answer 26

the culture is incubated to 40-45*c for several hours

Question 27

why does this occur?

Answer 27

to allow the lactobacillus to digest the milk proteins and ferment from lactose to lactic acid

Question 28

what is step 5 of the yoghurt making process?

Answer 28

the yoghurt mix becomes thick

Question 29

why does this occur?

Answer 29

because the bacteria digests the lactose forming lactic acid, as the pH becomes acidic, making the milk proteins coagulate

Question 30

what is step 6 of the yoghurt making process?

Answer 30

the yoghurt is stirred and cooled to 50*c

Question 31

why does this occur?

Answer 31

so a smooth consistency and so that the flavourings and fruit can be added without excessive warmth marring the flavour

Question 32

how does the lactobacillus respire?

Answer 32

anaerobically

Question 33

what does it produces and act as?

Answer 33

it produces lactic acid and this lowers the pH and acts as a preservative

Question 34

what is the anaerobic word equation for yoghurt?

Answer 34

glucose -> carbon dioxide + lactic acid