section 5: Uses of biological resources Flashcards
glasshouses and polyethene tunnels:
-the enclosed environment protects the crops from harsh weather conditions
-carbon dioxide levels, and so therefore rate of photosynthesis
-heat is trapped from the Sun, so the optimum temperature of enzymes can be reached
-the plants are protected from pests that can damage plants or carry diseases
factors affecting crop yield:
carbon dioxide:
-paraffin lamps can be burned to increase carbon dioxide levels
-this ensures that carbon dioxide is not the limitting factor in the rate of photosynthesis
temperature:
-the heat trapped by the sun in the glasshouse raises the temperature
-this allows the enzymes in photosynthesis to work at the optimum temperature and so the rate of photosynthesis increases
fertilisers:
-fertilisers contain nutrients that allow plants to grow faster
-these water-soluble minerals can be absorbed into the plant roots by active transport
-nitrates are required to make amino acids for proteins, to allow the 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
pest control + ads & disads:
-> using pesticides or biology control to prevent insects eating the plants, pesticides include fungicides, herbicides and insecticides
advantages:
-quick and efficient
-can kill entire populations
disadvantages:
-organisms can develop resistance
-non-specific so kills other organisms
-bioaccumulation can make it toxic to others in the food chain
-have to continuously apply
yeast:
-yeast uses anaerobic respiration in order to make bread rise:
glucose —> ethanol + carbon dioxide
C6H12O6 —> ethanol + CO2
-the carbon dioxide bubbles are what causes the bread to rise
practical: investigate the role of anaerobic respiration by yeast in different conditions
1) dissolve sugar in boiled water
2) mix yeast with sugar solution in a boiling tube
3) add a layer of oil on top in order to prevent oxygen from entering (ensuring that is is only anaerobic respiration taking place)
4) connect the boiling tube to a test tube of lime water
5) count the number of bubbles seen over a set time
-different conditions can be investigated, such as temperature (by using a water bath) or concentration of sugar
production of yoghurt:
-lactobacillus is a useful bacteria in making yoghurt
-milk contains a sugar called lactose, which lactobacillus can break down to form lactic acid
-this acid lowers the pH of the milk, which denatures proteins to give the yoghurt texture
the process of making yoghurt:
1) all equipment is sterilised to kill unwanted microorganisms
2) milk is heated to 72ºC for 15 seconds to kill any microorganisms in the milk-this is called pasteurisation
3) the milk is cooled and lactobacillus is added
4) the mixture is incubated at around 40ºC in a fermenter-here the bacteria breaks down lactose to lactic acid
5) the thickened yoghurt is produced and any flavouring, colorants or fruit are added before packaging
industrial fermenter:
-fermenters are containers that grow bacteria and fungi in large amounts, this can be useful when producing transgenic bacteria for example:
-aseptic conditions are required to ensure that no other microorganism grows and contaminates the containers
-nutrients are needed for the microorganism to use in respiration
-optimum temperature and pH are needed in order for enzymes to work at the high rate but are not denatured
-agitation by stirring paddles is required to ensure that the nutrients, oxygen, temperature, pH and microorganisms are distributed evenly
selective breeding + process:
-> is when humans choose which organisms to breed in order to produce offspring with a certain desirable characteristic (e.g. animals with more meat, plants with disease resistance or big flowers)
-this has been happening for many years since animals were domesticated and plants were grown for food
1) parents with desired characteristics are chosen
2) they are bred together
3) from the offspring those with desired characteristics are bred together
4) the process is repeated many times until all the offspring have the desired characteristic
inbreeding:
-breeding can lead to inbreeding
-breeding those with similar desirable characteristics means it is likely you are breeding closely related individuals
-this results in the reduction of the gene pool, as the number of different alleles reduce (as they mostly have the same alleles)
-this means if the environment changes or there is a new disease, the species could become extinct as they have the same genetic make-up (so the chance of a few organisms having a survival advantage and not dying is reduced)
-another problem is that the small gene pool leads to a greater chance of genetic defects being present in offspring, as recessive characteristics are more likely to be present
genetic engineering:
-> modifrying the genome of an organism by introducing a gene from another organism to give a desired characteristic
-plant cells have been engineered for disease resistance or to have larger fruits
-bacterial cells have been engineered to produce substances useful to humans, such as human insulin to treat diabetes
restriction enzymes:
-> enzymes which are able to cut DNA at specific sites, leaving ‘sticky ends’ (short sections of exposed, unpaired bases)
ligase enzymes:
-enzymes that are used to join pieces of DNA together
-the virus or plasmid DNA is then cut using the same restriction enzyme and the desired gene is placed inside and then joined by ligase enzymes
the process of human insulin production:
- the insuline gene for a healthy individual is ‘cut out’ using restriction enzymes leaving ‘sticky ends’
- a virus or 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 mutiply as it will now contain the modified gene
