Food Production

Question 1

What are greenhouses?

Answer 1

A greenhouse (or glasshouse) is a structure with transparent walls and roof, usually made of glass or clear plastic, that’s designed to grow and protect plants

Question 2

What are polytunnels?

Answer 2

A polytunnel is a tunnel-shaped structure made of strong plastic (polythene) stretched over hoops or frames.

Question 3

How do polytunnels and greenhouses work?

Answer 3

they provide controlled conditions for plants to grow and increase yeild

the transparent walls allow natural light for photosynthesis during summer, and additional lighting can be added to give a ‘longer day’ during winter

the greenhouse effect also occurs

heaters release CO2 and water vapour for photosynthesis and gives moist atmosphere reducing water lost by transpiration

hydroponic culture balances mineral ions for the crop

Question 4

Describe the greenhouse effect in glasshouses

Answer 4

short wavelength infrared radiation enters the glasshouse and is absorbed and re-radiated as longer wavelength infrared radiation and cannot escape through the glass. this heats up the glasshouse and reduces convection currents that would normally cause cooling.

Question 5

What are the types of fertilisers?

Answer 5

organic fertilisers and inorganic fertilisers

Question 6

What are organic fertilisers?

Answer 6

Organic fertilizers are natural materials derived from living things (plants or animals) that add nutrients to soil and increase growth.

For example manure made from the faeces of farm animals as their waste products contain excess nutrients they consumed which can help the growth of plants.

Question 7

What are inorganic fertilisers?

Answer 7

inorganic/chemical compounds that are used to add nutrients to soil and increase growth by replacing lost ions

For example, potassium nitrate, ammonium nitrate

Question 8

What are the drawbacks of inorganic fertilisers?

Answer 8

can lead to pollution problems and don’t improve soil structure like organic fertilisers do.

Question 9

What are the advantages of organic fertilisers?

Answer 9

improves soil structure as they contain decaying matter which is an essential part of soil

Question 10

Describe the process of nitrogen fixation in legumes

Answer 10

legumes have nitrogen-fixing bacteria in nodules in their roots and convert nitrogen gas in the soil into ammonium ions used to make proteins when passed to the plants. at the end of the season, decomposers convert nitrogen in proteins to ammonia and is oxidised to make nitrate by nitrifying bacteria for next years crop

Question 11

What are pests?

Answer 11

organisms that reduce the yeild of crop plants/stock animals

Question 12

How do pests reduce yeild?

Answer 12

they can reduce growth by consuming the crops, can affect the appearance/quality so unsuitable to sell

Question 13

What are pesticides?

Answer 13

chemicals used to kill pests

Question 14

What is biological control?

Answer 14

releasing other organisms to reduce numbers of a pest

Question 15

What are the type of pestcides?

Answer 15

herbicides (plant pests)
insecticides (insects)
fungicides (fungi)
molluscicides (snails/slugs)

Question 16

What are the drawbacks of pesticides?

Answer 16

pests may develop resistance to the pesticide through natural selection, can cause environmental damage, slow to decompose (persist in environment), build up in tissues of organisms (bioaccumalation), kill harmless insects that help the species

Question 17

What should the idea pesticide do?

Answer 17

control the pest effectively, biodegradable, kill only the specific pest, not accumulate, safe to transport/store/supply, easy to apply

Question 18

How does biological control work?

Answer 18

introduces parasites that kill the pest but doesn’t fully get rid of it. because if the parasite kills all of the pests they would die out too because they wont have food left. therefore only reduces the number of pests to a level where its not making any significant economical damage anymore

Question 19

What are the methods of biological control?

Answer 19

natural predator, herbivore, parasite, pathogenic organism (makes disease), sterile males, pheromones

Question 20

What do sterile males do in biological control?

Answer 20

mates with females but doesn’t produce offspring therefore overtime the population decreases

Question 21

What do pheromones do in biological control?

Answer 21

insects that produce natural chemicals to attract mates and then destroy them

Question 22

What are microorganisms?

Answer 22

living things that you can only see under a microscope, they are single celled

Question 23

What do microorganisms do?

Answer 23

they form colonies with millions of them together which can be visible to the human eye. they regulate waste products and themselves when they die. useful for producing food, drink and medicines

Question 24

What are some examples of microorganisms?

Answer 24

protoctists, fungi and bacteria

Question 25

What happens when yeast is deprived of oxygen?

Answer 25

it respires anaerobically glucose -> ethanol + carbon dioxide

Question 26

How is bread produced with yeast?

Answer 26

1. wheat flour, water and yeast combined to form dough 2. enzymes from the cereal grains in the wheat flour break down starch into sugars which are respired by the yeast. (extra sugar can be added this stage) 3. yeast respires aerobically producing water and carbon dioxide. the carbon dioxide helps the dough rise. 4. when dough is baked the gas bubbles expand giving the bread a light and cellular structure as well as killing the yeast cells and evaporating the ethanol produced from fermentation

Question 27

What is yoghurt?

Answer 27

fermented milk by lactic acid bacteria which turns the liquid into a semi-solid food with a sour taste

Question 28

Describe the process to produce yoghurt`

Answer 28

1. milk pasteurised to 72 degrees celsius for 15-30 minutes to kill natural bacteria 2. milk is homgenised to disperse fat globules and even out the liquid 3. milk is then cooled to 40-45 degrees celsius and inoculated with starter culture (lactobacillus) 4. kept at this temperature for several hours until the pH falls to 4.4 5. the mixture coagulates as the milk proteins denature and form semi solids 6. fermentation completed and yoghurt stirred and cooled to 5 degrees 7. flavourings, colours, mix-ins added before packaged for sale

Question 29

What is lactobacillus?

Answer 29

the bacteria that produces lactic acid and digests the milk proteins

Question 30

What does the drop in pH do to yoghurt?

Answer 30

reduces the reproduction of lactic acid bacteria. doesn't fully kill them though, just prevents growth of other microorganisms and preserves nutrients in the milk

Question 31

What is a fermenter?

Answer 31

vessel used to grow microorganisms used for fermentation

Question 32

What is an industrial fermenter?

Answer 32

large tanks holding up to 200000dm^3 of a liquid culture that control the environmental conditions

Question 33

What are the aseptic precautions in industrial fermenters?

Answer 33

prevent contamination of unwanted organisms by filtering the air or sterilising the fermenter with very hot steam and pressure

Question 34

What is the purpose of industrial fermenters?

Answer 34

to use microorganisms to transform raw materials into valuable products

Question 35

What would happen if the industrial fermenter is not sterilised?

Answer 35

bacteria/fungi would compete with the organism in the culture reducing the yield of the product and would be contaminated with waste products of the foreign organism