5.1 Food production

Question 1

biological control of pests

Answer 1

use of other species to kill pests

Question 2

intraspecific predation

Answer 2

where an organism of one species kills an organism of a different species

Question 3

lactobacillus

Answer 3

a bacterial species used to make yoghurt

Question 4

pesticides

Answer 4

chemicals used to kill pests
can be split into herbicides which are used to kill weeds and insecticides which are used to kill insects

Question 5

yeast

Answer 5

unicellular fungi used to produce bread
they anaerobically respire to produce carbon dioxide which makes the bread rise and the ethanol which is also produced evaporates when the bread is heated

Question 6

What are the steps to yogurt production?

Answer 6

1. the equipment is sterilised
2. the milk is pasteurised by heating
3. the bacterial culture is added to the cooled jacket and left at 46 degrees C for about 4 hours
4. samples are taken to see if the yoghurt is ready
5. flavours and colours are added, yoghurt is packaged

Question 7

What is the purpose of the cooling jacket in industrial fermenters?

Answer 7

Removes heat energy, stopping the fermenter overheating and enzymes denaturing.

Question 8

What is the purpose of the air filter in industrial fermenters?

Answer 8

Filters air coming in, maintaining sterile conditions.

Question 9

What is the purpose of the stirrers in industrial fermenters?

Answer 9

Keep the broth well stirred to oxygenate all parts of the fermenter
prevent micro-organisms settling.

Question 10

What is the purpose of the growth medium in industrial fermenters?

Answer 10

Contains all necessary glucose and amino acids for micro-organism
growth.

Question 11

What is the purpose of the super-heated steam in industrial fermenters?

Answer 11

Applied before the fermenter is used, killing unwanted micro-organisms.
Leaves only water with no other residue

Question 12

Why is the milk initially pasteurised?

Answer 12

to kill any unwanted bacteria

Question 13

What is the role of lactobacillus in yoghurt making?

Answer 13

Lactobacillus respires anaerobically producing lactic acid.
This 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.

Question 14

Why is the yogurt further cooled to 5 degree C?

Answer 14

to help preserve the yoghurt