uses of biological resources

Question 1

selective breeding

Answer 1

breeding organisms to get the best offspring

maximum yield of plants and animals

selecting for certain alleles that code for the traits that we want

happens over many generations as we keep picking the most desirable organisms

• leads to inbreeding, less variation (makes all crops more susceptible to disease) and reduced gene pool of population

Question 2

increasing crop yields

Answer 2

• ideal conditions
• fertilizers
• pest control

Question 3

ideal conditions for crop yields

Answer 3

glasshouses and polythene tunnels are used the carefully control the conditions

1. glasshouses trap heat that keeps the plants warm
2. artificial light is used when the sun goes down
3. paraffin heaters produce carbon dioxide for photosynthesis of the plants

Question 4

fertilizers

Answer 4

provide more minerals for plants or replace missing ones that have been taken by other crops.

minerals needed e.g nitrogen, potassium and phosphorus

minerals are needed for plant growth

Question 5

pest control

Answer 5

• pesticides
• biological control

Question 6

pesticides

Answer 6

• chemicals
• poisonous to humans so doses have to be carefully controlled
• harmful to some other wildlife
  + kills pests

Question 7

biological control

Answer 7

introduces other organisms to reduce pests, e.g predators, bacteria, parasites

+ longer lasting effects than pesticides
+ less harmful to wildlife
- can cause more problems

Question 8

fermentation

Answer 8

when microorganisms break sugars down to release energy (usually by anaerobic respiration)

Question 9

how yoghurt is made

Answer 9

1. equipment is sterilized
2. milk is pasteurised then cooled
3. lactobacillus bacteria are added and the mixture is incubated in a fermenter
4. bacteria ferment the lactose sugar to form lactic acid
5. lactic acid causes the milk to clot and form yoghurt

Question 10

fermenters

Answer 10

• allows microorganisms to grow and reproduce
• optimum conditions for maximum yield
• nutrients are provided in the liquid culture medium (what the fermenter is full of)
• optimum pH for enzymes of the microorganisms
• water-cooled jacket ensures that the temperature is not too hot by absorbing some of the heat
• paddles stir mixture to keep microorganisms in suspension to ensure that they are receiving all the nutrients needed to grow, the medium is agitated around the vessel
• oxygen for respiration is pumped through sterile air
• aseptic conditions increases the product yield because microorganisms aren’t competing with other organisms + no contamination: vessels are therefore sterilised between uses with superheated steam

Question 11

yeast in the production of bread

Answer 11

• yeast, flour, water and a bit of sugar makes the bread dough
• dough is left in a warm place to rise (role of the yeast)
• enzymes break down the carbs on the flour into sugar
• yeast uses these sugars in aerobic respiration to produce CO2
• once the yeast runs out of oxygen it switches to anaerobic respiration (fermentation) produces CO2 + ethanol
• yeast continues to ferment in the oven until temp gets to high and it dies
• when yeast dies bread stops rising