5. USE OF BIOLOGICAL RESOURCES

Question 1

5.5 anaerobic respiration happens in

Answer 1

plant cells, animals and some microorganisms
(such as yeast)

Question 2

5.5 anaerobic respiration in yeast is used during

Answer 2

beer brewing and bread making

Question 3

5.5 glucose ——->

Answer 3

ethanol + carbon dioxide

Question 4

5.5 ethanol + carbon dioxide <——–

Answer 4

glucose

Question 5

5.5 C6H12O6 ———>

Answer 5

2C2H5OH + 2CO2

Question 6

5.5 bubbles of carbon dioxide gas in bread e…

Answer 6

expand the dough making it rise

Question 7

5.5 high temperatures in bread-making mean

Answer 7

the ethanol does not remain in the bread
(it evaporates)

Question 8

5.6 practical: a way to investigate anaerobic respiration is to

Answer 8

study the production of carbon dioxide under diff conditions

Question 9

5.6 practical: if you bubble carbon dioxide through limewater

Answer 9

it turns cloudy white (milky)

Question 10

5.6 practical: in the presence of carbon dioxide the hydrogen carbonate indicator changes

Answer 10

from purple to yellow

yellow = high CO2
purple = low CO2

Question 11

5.6 practical: describe a practical for studying production of carbon dioxide

Answer 11

get 2 boiling tubes
dissolve sugar in boiled water
add yeast and mix to form suspension
pour into test tube 1
add vegetable oil into tube 1
connect delivery tube to boiling tube 2
tube 2 contains limewater or hydrogen carbonate indicator

the veggie oil prevents oxygen - no aerobic respiration only anaerobic

the conditions that can be investigated include:
temperature, concentration of sugar & type of sugar

Question 12

5.7 what is yoghurt made with

Answer 12

lactobacillus bulgaricus

Question 13

5.7 first the milk is p… to ?

Answer 13

pasteurised to kill bacteria

Question 14

5.7 the mixture is maintained at 46*C so

Answer 14

the bacterias enzymes are not denatured

Question 15

5.7 lactobacillus respires anaerobically producing

Answer 15

lactic acid

Question 16

5.7 how does lactobacillus respire

Answer 16

anaerobically

Question 17

5.7 what does lactic acid do

Answer 17

lowers the pH
coagulates the milk protein
gives yoghurt its texture and flavour

Question 18

5.7 steps to produce yoghurt

Answer 18

sterilise equipment
pasteurise milk by heating
add bacterial culture to
cooled milk
leave at 46C for 4 hours
take samples if yoghurt is ready
add flavour and colour
cool yoghurt to 5C to preserve
package yoghurt

Question 19

5.7 what is lactobacillus bulgaricus

Answer 19

it is a bacteria

Question 20

5.7 why is yoghurt sour and has its unique taste

Answer 20

because of the anaerobic reaction creating lactic acid