Use of Biological Resources - Food Production

Question 1

how do glasshouses and polyethene tunnels increase crop yield?

Answer 1

• crops are protected from the effects of weather
• crops are protected from pests
• heat from the sun is trapped, creating a warm climate close to optimum temperature for plant enzymes
• artificial hearing can make temperature closer to optimum
• additional carbon dioxide can be added by burning paraffin lamps
• plants can be watered more regularly

Question 2

what is the effect on crop yield when carbon dioxide is increased?

Answer 2

• as the concentration of carbon dioxide is increased, the rate increases
• carbon dioxide is a reactant in photosynthesis so an increase in carbon dioxide means more photosynthesis can occur
• as concentration increases beyond a certain point, the rate will plateau as carbon dioxide is not the limiting factor

Question 3

what is the effect on crop yield when temperature is increased?

Answer 3

• as temperature increases, rate will increase at first
• this is because the increase in temperature is moving closer to the optimum temperature for the photosynthesis-related enzymes
• as temperature increases beyond optimum, enzymes start to denature

Question 4

how does the use of fertilised increase crop yield?

Answer 4

• fertilisers containing minerals are absorbed through plant roots via active transport
• these minerals cause plants to grow faster, increasing yield

Question 5

what are the advantages of pesticides?

Answer 5

• efficient
• immediate effect
• kills the entire population

Question 6

what are the disadvantages of pesticides?

Answer 6

• pests can develop resistance
• may kill other organisms
• can bioaccumulate in the food chain

Question 7

what are the advantages of biological control?

Answer 7

• natural method
• no resistance
• can target specific species
• longlasting
• minimal effort

Question 8

what are the disadvantages of biological control?

Answer 8

• may kill other organisms
• takes time to effect
• cannot kill the entire population
• organisms used for control may die in the new environment

Question 9

what is the role of yeast in making bread?

Answer 9

• yeast is mixed into dough prior to baking
• while baking, yeast rapidly uses up all oxygen present in the dough via aerobic respiration
• anaerobic respiration will occur to produce carbon dioxide, which forms bubbles that make the dough rise

Question 10

how would you investigate the anaerobic respiration of yeast?

Answer 10

• mix a boiling tube of sugar solution with yeast, covering it with a layer of oil to prevent the entry of oxygen
• a boiling tube is connected to a test tube of limewater via a capillary tube that is kept airtight by a bung
• the boiling tube is placed in a water bath of a set temperature
• the rate of carbon dioxide production is measured by the number of bubbles produced in a fixed time in the test tube of Limewater

Question 11

what is fermentation?

Answer 11

when microorganisms break sugars down to release energy

Question 12

how is yoghurt made?

Answer 12

1. equipment is sterilised to kill unwanted microorganisms
2. milk is pasteurised to kill unwanted microorganisms
3. lactobacillus bacteria are added and the mixture is incubated in a fermenter
4. the bacteria ferment the lactose sugar in the milk to form lactic acid
5. lactic acid causes milk to clot and solidify into yoghurt
6. flavours and colours are added

Question 13

what are microorganisms grown in (in industry)?

Answer 13

fermenter

Question 14

what do fermenters contain which help microorganisms reproduce?

Answer 14

liquid culture medium

Question 15

how are nutrients needed for fermentation provided in fermentors?

Answer 15

nutrients needed by the microorganisms for growth are provided in the liquid culture medium

Question 16

how is rate of respiration kept high in fermentors?

Answer 16

pH is monitored and kept at the optimum level for the microorganism’s enzymes
temperature is kept at the optimum level by a water-cooled jacket.
if oxygen is needed, its added by pumping in sterile air

Question 17

why are fermentors sterilised?

Answer 17

sterilisation kills unwanted microbes, so microorganisms aren’t competing with each other and the product isn’t contaminated

Question 18

why do fermentors have paddles?

Answer 18

so microorganisms can be kept in contact with fresh medium, so they can always access the nutrients needed.