Paper 1 - Use of Biological Resources Flashcards
Describe how glasshouses/polythene tunnels can be used to increase the yield of certain crops
- Keeps plants enclosed to prevent pests and disease
- Farmers can control the water supplied to crops
- Artificial light can be used so that plants can photosynthesize at night time
- Traps heat to keep plants warm. In winter a farmer can use a heater to maintain optimum temperature
What are the effects on crop yield of increased carbon dioxide and increased temperature in glasshouses?
- Increasing temperature and CO2 concentration allows for an increase in the rate of photosynthesis
- plants grow faster and larger - the crop yield is higher
How can the use of fertiliser increase crop yield?
Farmers use fertilisers to provide more essential minerals (nitrogen potassium and phosphorus) to increase crop yield
What are the reasons for pest control?
- Using pest control kills pests that feed on crops
- So fewer crops are damages or destroyed
- So crop yield is higher
What are the advantages and disadvantages of using pesticides with crop plants?
Advantages
- Cheap
- Immediate effect
- Kills the entire population of pests
Disadvantages
- Organisms may develop resistance
- May kill other beneficial organisms
- Bioacculimation may occur
- Need to be repeatedly applied
What are the advantages and disadvantages of using biological control with crop plants?
Advantages
- No pollution
- No resistance
- Long lasting
- Does not need to be repeatedly applied
Disadvantages
- May eat other organisms
- Not instantly effective
- Cannot kill entire population of pest
- May move out of desired area
What is the role of yeast in the production of food including bread?
- Bread dough is made by mixing yeast with flour, water and sugar
- Dough is left in a warm place to rise with the help of yeast
- Enzymes break down carbohydrates in the flour into sugars
- The yeast then uses these sugars in aerobic respiration, producing CO2
- When O2 runs out, yeast anaerobically respires, also known as fermentation, producing CO2 and ethanol
- CO2 produced is trapped in bubbles in dough
- These pockets of gas expand and the dough begins to rise
- Dough is baked in the oven and the yeast is killed by the high temperatures and ethanol is boiled away
What is the role of bacteria (Lactobacillus) in the production of yoghurt?
- Equipment is sterilised to kill any unwanted microorganisms
- Milk is pasteurised (heated to 72℃ for 15 seconds) to kill harmful microorganisms and is then killed
- Lactobacillus bacteria are added, and the mixture is incubated (heated to about 40℃) in a vessel called a fermenter
- The bacteria ferment the lactose sugar in the milk to form lactic acid
- Lactic acid causes the milk to clot, and solidify into yoghurt
- Flavours and colours are added and the yoghurt is packaged
What is the use of an industrial fermenter? Explain the need to provide
suitable conditions in the fermenter.
- pH is monitored and kept at the optimum level for the microorganism’s enzymes to work efficiently. This keeps the rate of reaction and product yield as high as possible
- Nutrients needed by the microorganisms for growth are provided in the liquid culture medium
- Microorganisms are kept in contact with fresh medium by paddles that circulate the medium around the vessel. This increases the product yield because microorganisms can always access the nutrients needed for growth
- If the microorganisms need O2 for respiration, it’s added by pumping in sterile air. This increases product yield because microorganisms can always respire to provide energy for growth
- Vessels are sterilised between uses with superheated steam that kills unwanted microbes. Having aseptic conditions increases the product yield because the microorganisms aren’t competing with other organisms. It also means that the product is not contaminated
- The temperature is also monitored and kept at an optimum level. A water-cooled jacket makes sure it doesn’t get so hot that the enzymes denature
How can selective breeding develop organisms with desired characteristics?
- Parents with desired characteristics are chosen
- They are bred together
- From the offspring, those with the desired characteristics are bred together
- The process is repeated many times until all offspring have desired characteristics
How are restriction enzymes used to cut DNA at specific sites and ligase
enzymes used to join pieces of DNA together?
- The gene that is to be inserted is located in the original organism
- Restriction enzymes are used to isolate the required gene, leaving it with sticky ends
- A bacterial plasmid is cut by the same restriction enzyme leaving it with corresponding sticky ends
- The plasmid and the isolated gene are joined together by DNA ligase enzyme
- If two pieces of DNA have matching unpaired bases (because they have been cut by the same restriction enzyme), DNA ligase will link them to form a single, unbroken molecule of DNA
How can plasmids and viruses act as vectors, which take up pieces of
DNA, and then insert this recombinant DNA into other cells?
- Plasmids and viruses can act as vectors for genetic engineering
- They take up pieces of DNA and then insert this recombinant DNA into other cells
- Viruses transfer DNA into human cells or bacteria
- Plasmids transfer DNA into bacteria or yeast
- The genetically engineered plasmid is inserted into a bacterial cell
- When the bacteria reproduce the plasmids are copied as well and so a recombinant plasmid can quickly be spread as the bacteria multiply and they will then all express the gene and make the human protein
- The genetically engineered bacteria can be placed in a fermenter to reproduce quickly in controlled conditions and make large quantities of the human protein
How are large amounts of human insulin manufactured from genetically modified bacteria that are grown in a fermenter?
- Insulin gene of a healthgy individual is cut out using restriction enzymes leaving sticky ends
- A virus of bacterial plasmid is cut using the same restriction enzyme to also create sticky ends
- The sticky ends from the virus or plasmid and the sticky ends from the genes are then joined together by ligase enzymes
- The combined loop is placed in a vector, such as a bacterial cell, and then allowed to multiply as it will not contain the modified gene
How genetically can modified plants be used to improve food production?
- Crops can be genetically altered to increase food production
- Crops can be genetically altered to be resistance to insects so that farmers dont have to spray as many pesticides so wildlife doesnt each the crop and isn’t harmed
- Crops can be genetically altered to be resistance to herbicides so that farmers can spray herbicides to kill weeds without affecting the crop
Define transgenic
The transfer of genetic material from one species to a different species
