bio goat69

describe the role of restriction enzymes

• they cut DNA at specific sites leaving ‘sticky ends’

describe the role of ligase enzymes

• they join pieces of DNA together and seal the ‘sticky ends’

describe the process of genetic engineering (human insulin production)

1. Restriction enzyme cuts out the human insulin gene and cuts open the vector DNA.

2. Vector DNA and insulin gene DNA are mixed with ligase enzymes.

3. Ligases join the DNA fragments, forming recombinant DNA.

4. Recombinant DNA is inserted into host cells.

5. Transgenic bacteria now produce human insulin protein from the inserted gene.

describe vectors

• something used to transfer DNA into a cell

describe the different types of vectors

• plasmids - small, circular molecules of DNA that are transferred between bacteria

• viruses - insert DNA into organisms they infect

describe how GM plants improve food production

• making them resistant to insects - farmers don’t have to spray as many pesticides - crop yield increased

• making them resistant to herbicides - farmers can spray their crops to kill weeds without affecting the crop - crop yield increased

define the term transgenic

• the transfer of genetic material from one species to a different species

effects of pollution by sulfur dioxide

• released when fossil fuels are burned

• dissolves in water in clouds to form acid rain

• acid rain alters river pH causing organisms to die

• acid rain corrodes metals

effects of pollution by carbon monoxide

• released when fossil fuels are burned through incomplete combustion

• has a higher affinity for haemoglobin than O2 so it reduces O2 transport

• this leads to insufficient oxygen, less respiration and even death

state the 5 greenhouse gases

• CO2 (deforestation)

• nitrous oxide (from fertilisers)

• CFC’s (from refrigerators)

• methane (from cattle farming)

• water vapour (from rivers)

describe the effects of global warming

• increased global temp

• water levels rise as glaciers melt

• extreme weather

• loss of habitats

• species could become extinct

• decreased biodiversity

effects of pollution of water by sewage

• sewage is rich in minerals and nutrients which allows algae to grow

• decomposers respire aerobically to break down sewage, decreasing oxygen levels

• sewage also contains bacteria that can respire aerobically

• algal bloom stops light from reaching aquatic plants, causing them to die

• this leads to O2 depletion meaning other aquatic organisms die

describe the biological consequences of eutrophication

• fertilisers are washed off by the rain from the land into nearby rivers and lakes

• excess nutrients that are washed into the lakes encourage algae to grow

• algal bloom then occurs which blocks sunlight reaching aquatic plants so they cannot photosynthesize

• this leads to O2 depletion and therefore death

define deforestation

• the mass clearing of trees from an area

describe the effects of deforestation on the environment

• leaching - trees usually take up nutrients and minerals from the soil for growth so without trees, these will run into rivers/lakes

• soil erosion - tree roots help stabilise soil so without trees, soil will be washed away by the rain

• disturbance to cycles - transpiration from trees releases water vapour which contributes to the water cycle and carbon cycle

• imbalance of atmospheric gases - less trees means less CO2 uptaken for photosynthesis and therefore increased CO2 levels in atmosphere (greenhouse gases) and decreased O2 - also combustion of trees releases CO2 into atmosphere

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

Features of an insect-pollinated plant

• petals - large and colourful

• nectar - scented

• pollen grains - sticky

• anthers - inside flower - stiff and attached

• stigma - inside flower - sticky

Features of an wind-pollinated plant

• petals - small and dull

• nectar - no nectar/scent

• pollen grains - smooth and light

• anthers - outside flower - loose on long filaments

• stigma - outside flower - feathery

Describe the steps of seed and fruit formation

1. pollen grains land on stigma

2. pollen tube grows out the pollen grain, down the style into the ovary and then to the ovule

3. male nucleus travels down the pollen tube to fuse with the female egg nucleuus in the ovule, forming a zygote

4. zygote undergoes mitosis to form a seed

5. ovule becomes the seed

6. the ovary will become the fruit

Describe the conditions needed for seed germination

WOW

• Water - activates enzymes to break down starch in seeds

• Oxygen - needed for aerobic respiration to release energy for growth

• Warmth - optimum temp for enzymes will increase growth rate

Describe a natural method of asexual reproduuction

• runners (e.g strawberries)

Describe an artificial method of asexual reproduuction

• cuttings