Food Production and Selective Breeding

describe how glasshouses can be used to increase the yield of certain crops

• provide a controlled environement where conditions can be optimized

• temp - increased temp leads to enzymes being at optimum temp and working more efficiently and having more kinetic energy therefore more photosynthesis

• CO2 - levels of carbon dioxide are increased to allow for an increased photosynthesis rate and therefore more growth

• light - increased artificial lighting allows for increased photosynthesis rate

describe how polythene tunnels can be used to increase the yield of certain crops

• protect crops from extreme weather

• temperature can be increased to allow for optimum enzyme temp and therefore increased photosynthesis

• prevents the entry of pests that can harm the crops and reduce yield

how does the use of fertiliser increase crop yield

• contains nutrients that allow plants to grow faster

• nitrates make amino acids for proteins to allow plants to grow

• phosphates are required for respiration and root growth

• potassium is needed for growth of flowers and fruit, as it allows enzyme reactions to take place

• (NPK fertilisers)

describe pest control

• using pesticides e.g. (chemical pesticides) or biological control (e.g. ladybirds) to prevent insects from eating plants therefore increasing crop yield

• Insecticides kill insects

• Herbicides kills weeds

• Fungicides kill fungal pests

describe advantages of pesticides

• have an immediate effect

• cheap and accessible

• kills all pests

describe disadvantages of pesticides

• organisms they are meant to kill can become resistant to pesticides

• non specific so it can kill other organisms too

• have to continuously apply

• bioaccumulation can make it toxic to others in food chain

describe advantages of biological control

• organisms they are meant to kill can’t develop resistance

• no need to reapply

• avoids bioaccumulation

• specific so won’t kill other organisms

• long lasting

describe disadvantages of biological control

• doesn’t have an immediate effect

• cannot kill all pests

• may become a pest itself

• may eat other organisms instead of pests

describe the role of yeast in the production of food (bread)

• anaerobically respires

• CO2 bubbles cause bread to rise

• yeast gets killed off at high temp when bread bakes due to the enzymes denaturing

describe the role of lactobacillus in the production of yoghurt

• bacteria which breaks down lactose found in milk, forming lactic acid

• the lactic acid lowers milk pH, denaturing proteins to give the yoghurt texture

explain the process of making yoghurt

1. all equipment is sterilised to kill unwanted microorganisms

2. milk is heated to 72°C for 15 seconds to kill microorganisms (pasteurisation)

3. milk is cooled to 45°C to prevent enzymes denaturing and lactobacillus is added

4. mixture is incubated at 40°C in a fermenter - lactobacillus breaks down lactose into lactic acid

5. thick yoghurt is produced and any flavourings, colourings or fruit are added before packaging

describe the importance of aseptic conditions in a fermenter

• ensures no other microorganism grows and contaminates the containers - increases product yield as competition is eliminated

• prevents the product being contaminated

describe the importance of optimum temp and pH in a fermenter

• needed for enzymes to work at a high rate but do not denature

describe the role of stirring paddles in a fermenter

• ensures that O2 is distributed for respiration

• ensures that nutrients are distributed for growth

• ensures that heat is distributed

describe the importance of nutrients in a fermenter

• oxygen is added by pumping in sterile air

• oxygen is needed for the microorganisms to respire aerobically to provide energy for growth

• increases product yield

describe the role of the cooling jacket in a fermenter

• pumps cold water through to ensure temp does not exceed optimal level which would make enzymes denature

define selective breeding

• when humans breed organisms to produce offspring with certain desirable characteristics

describe the general process of selective breeding

• parents with desired characteristics are chosen

• they are bred together

• offspring with the desired characteristics are bred together

• this process is repeated over many generations until all the offspring have the desired characteristic