5. use of biological resources Flashcards
done
what is the role of yeast in breadmaking
- if given the correct conditions (like warm, damp surroundings), yeast carries out anaerobic respiration- the yeast produces enzymes that break down the starch in the flour, releasing sugars that can then be used by the yeast for anaerobic respiration
- the waste product of this is carbon dioxide, which gets trapped into small air pockets in the dough which causes the dough to rise
how does bread rise by using yeast?
the carbon dioxide produced by the yeast during anaerobic respiration is trapped in small air pockets in the dough, causing the dough to rise
explain why bread doesn’t contain any alcohol when the waste product of anaerobic respiration is ethanol
any ethanol produced by the yeast is evaporated in the heat
the yeast is also killed by the high temperatures during baking which ensures no further respiration
what bacteria is used to make yoghurt
lactobacillus bulgaricus
describe how you would make yoghurt
- first, all equipment is sterilised
- milk is pasteurised and then cooled
- bacteria called lactobacillus bulgaricus is added
- the mixture is incubated and kept at 46C (optimum temp)
- lactobacillus respires anaerobically, producing lactic acid
- this lowers the pH and acts as a preservative
- the acid also coagulates the milk protein, which gives yoghurt its texture
what are some problems with selective breeding?
- can lead to inbreeding- results in a reduction in the number of alleles in a population- leads to an increased chance of organisms inheriting harmful genetic defects and being vulnerable to new diseases
selective breeding answer guideline:
- select the individuals with ‘desirable characteristic’ and breed them together
- choose the offspring with the ‘desired characteristic’ and breed them together
- repeat for many generations
name 3 differences between natural selection and artificial selection:
- N occurs naturally, A only occurs when humans intervene
- N usually takes a long time to occur, A takes less time
- N results in development of populations that are better adapted to their environment and survival, A increases vulnerability and decreases immunity
what are industrial fermenters
containers used to grow (‘culture’) microorganisms like bacteria and fungi in large amounts
what can industrial fermenters be used for
- brewing beer, making yoghurt and mycoprotein
- as well as other processes not involving food, like producing genetically modified bacteria and moulds that produce antibiotics (like penicillin)
what is an advantage of using a fermenter
conditions can be carefully controlled to produce large quantities of exactly the right type of organism
what conditions can you control in fermenters
- aseptic precautions
- nutrients
- optimum temperature
- optimum pH
- oxygenation
- agitation
how and why is aseptic precautions controlled in fermenters
- fermenter is cleaned by steam to kill microorganisms and prevent chemical contamination
- ensures only the desired microorganisms will grow
how and why is nutrients controlled in fermenters
- nutrients are needed for use in respiration to release energy for growth
- and to ensure the microorganisms are able to reproduce
how and why is optimum temperature controlled in fermenters
- temperature is monitored using probes and maintained using the water jacket
- to ensure optimum environment for enzymes to increase enzyme activity (enzymes will denature if too high, or work too slowly if too low)
how and why is optimum pH controlled in fermenters
- pH inside fermenters are monitored using a probe
- to check it is at the optimum value for the particular microorganism being grown
- pH can be adjusted, if necessary, using acids or alkalis
how and why is oxygenation controlled in fermenters
- oxygen is needed for aerobic respiration to take place
how and why is agitation controlled in fermenters
- stirring paddles ensures that microorganisms, nutrients, oxygen, temperature and pH are evenly distributed throughout the fermenter
how can glasshouses be used to increase the yield of certain crops
- they can manipulate conditions:
- artificial heating (enzymes controlling photosynthesis can work faster at slightly higher temperatures- only used in temperate countries such as the UK)
- artificial lighting (plants can photosynthesise for longer)
- increasing CO2 content of the air inside (plants can photosynthesise quicker)
- regular watering
how can polythene tunnels be used to increase the yield of certain crops
- they are plastic tunnels that cover crops
- protect crops grown outside from the effects of weather (excessive wind, rain, extreme temperature)
- increase temperature slightly inside
- prevent the entry of pests (could damage plants or diseases that can kill plants)
what are the three main limiting factors of photosynthesis
- temperature
- light intensity
- carbon dioxide concentration
why is temperature a limiting factor of photosynthesis
- as temp increases, rate also increases (controlled by enzymes)
- but this trend only continues to a certain point as enzymes denature and rate of reaction decreases
why is light intensity a limiting factor of photosynthesis
- more light, raster the rate
- trend continues until some other factor required prevents the rate from increasing further as its now in short supply
why is carbon dioxide a limiting factor of photosynthesis
- one of the raw materials required
- more co2, faster reaction
- trend continues until some other factor required prevents the rate from increasing further as its now in short supply
what are fertilisers
increase the amount of key nutrients in the soil for crop plants, meaning they can grow larger and more healthy which increases yields
what are pesticides
chemicals that kill off unwanted insects and weed species, meaning there is less damage done to crop plants by insects, as well as reducing competition from other plant species which increases yields
how do fertilisers increase crop yields
- plants require a range of mineral ions in order to grow well
- as crop plants take up these mineral ions from the soil, the mineral ions need to be replaced
- fertilisers are used to replace these
- can make crops grow faster and bigger so yields are increased
- can be organic or chemical
what are organic fertilisers
commonly used by farmers, include farmyard manure and compost
what are chemical fertilisers
- applied to the soil as dry granules or can be sprayed on in liquid form
- mainly provide crop plants with nitrogen, phosphorus and potassium
how does nitrogen affect plants
- absorbed in the form of nitrates
- needed to make amino acids (building blocks of proteins)
- lack of nitrogen causes weak growth and yellowing of the leaves
how does phosphorous affect plants
- absorbed in the form of phosphates
- needed to make DNA and cell membranes
- lack of phosphorous can cause poor root growth and discoloured leaves
how does potassium affect plants
- absorbed in the form of various compounds of potassium
- allows enzyme reactions to take place to produce ATP in respiration as well as being needed for the enzymes involved in photosynthesis
- lack of potassium can cause poor growth of flowers and fruits, as well as brown spots on leaves
what are some examples of pesticides
- insecticides (kill insect pests)
- herbicides (kill plant pests)
- fungicides (kill fungal pests)
what are the reasons for pest control
- pests such as insects and other animals can damage crops by eating them
- weeds can outcompete crop plants for space, water and soil nutrients
- fungi can infect crop plants and spread disease which can affect growth and yield
- all of these can be controlled by using pesticides (chemical control) or by introducing other species (biological control)
what are the advantages of using pesticides
- easily accessible and relatively cheap
- have an immediate effect
- kills the entire population of pests
what are the disadvantages of using pesticides
- organisms they are meant to kill can develop a resistance to them
- they are non-specific chemicals and can often kill other beneficial organisms (e.g. some insecticides may kill bees which are important pollinators of crops)
- they can be persistent chemicals- means they do not break down in the body and can accumulate in great concentrations at the top of food chains and harm top predators (bioaccumulation)
- need to be repeatedly applied
what is biological control
- involves using a natural predator to eat the pest species and therefore reduce the impact of the pest on crop yields
- can happen naturally – for example, ladybirds eat aphids
- usually, a species is introduced specifically to prey on the pest species – for example, parasitic wasps can control whitefly in glasshouse tomato crops
- based on a predator-prey cycle, they do not completely remove a pest, but keep it at lower level
what are the advantages of using biological control
- natural method- no pollution
- no resistance
- can target specific species
- long lasting
- does not need to be repeatedly applied
what are the disadvantages of using biological control
- may eat other organisms instead of the pest
- takes a longer period of time to be effective
- cannot kill entire population- some pests will always be present
- may not adapt to new environment or may move out of the area
- may become a pest itself
what are the methods of fish farming
- maintaining water quality
- controlling intraspecific predation
- controlling interspecific predation
- control of disease
- removal of waste products
- quality and frequency of feeding
- use of selective breeding
explain how maintaining water quality helps fish farming
- water is filtered to remove waste and harmful bacteria to prevent diseases
- water is also cleaned to maintain high levels of oxygen for aerobic respiration
explain how control of intraspecific predation helps with fish farming
- intraspecific predation: predators within the same species
- fish are separated by size and age so they don’t eat each other or fight
explain how control of interspecific predation helps fish farming
- interspecific predation: predation between different species
- different species of fish are separated by fences, nets and tanks to prevent fighting
explain how control of disease helps with fish farming
- antibiotics are given to fish to prevent disease which might otherwise spread quickly due to their close confinement, increasing the chances of survival
- they are also kept in small numbers to minimise the spread of diseases
explain how removal of waste products helps with fish farming
- water can be filtered to remove waste products such as faeces and sewage
- fences, nets and tanks are cleaned or location of fish can be changed to ensure clean water
explain how quality and frequency of feeding helps with fish farming
- fish are fed food that is high in nutrients to ensure fast growth
- they are fed frequently but in small amounts so they do not overeat or start eating each other
explain how use of selective breeding helps with fish farming
- fish are separated by gender so that selective breeding can be used by farmers to only allow fish with desired characteristics to reproduce
- this ensures that the stock of fish is fast growing as these genes get passed on much more frequently
what is recombinant DNA
DNA that is taken from two different organisms combined into one strand
what is a transgenic organism
organisms which have received genes from another organism (different species)
what is genetic modification
the transfer of a gene or section of DNA from one organism into the DNA of another organism
what is the role of restriction enzymes in genetic modification
- to cut specific DNA sequences, allowing for the isolation of genes
- these enzymes cut DNA at specific nucleotide sequences, resulting in fragments with sticky ends
what are the two enzymes used to cut DNA and join DNA for genetic engineering
restriction enzyme and DNA ligase
what is the role of ligase in genetic modification
joins the plasmid and isolated gene together (if they have complementary sticky ends) to form a single, unbroken molecule of DNA
what is a plasmid
small circular loops of DNA that contain genes
what do plasmids and viruses act as
vectors- they take up recombinant DNA and insert it into other cells
explain how genetically modified bacteria (used to produce insulin) are produced
- restriction enzyme is used to cut gene (that codes for human production of insulin)
- same restriction enzyme is used to cut bacterial plasmid to produce complementary pairings
- ligase enzyme used to insert gene into plasmid
- plasmid/vector inserted into bacterium
- bacterium clones the plasmid
what are genetically modified plants
plants that have had foreign DNA inserted into their genome
describe the conditions needed in an industrial fermenter for manufacturing insulin
- sterilised fermenter - prevents competition from other bacteria
- oxygen - aerobic respiration
- stirring mixture - ensures nutrients are spread evenly, prevents settling
- monitoring temp and using cooling jacket if needed - optimum temp for enzymes
- nutrient medium - provides food for bacteria for respiration
what are the advantages of GM crops
- more precise method than selective breeding
- higher crop yield
- less pesticide use so less pollution
- disease resistant/pest resistant
what are the disadvantages of GM crops
- long term effects are unknown
- may affect food chains
- reduces variation
describe the process of micropropagation (tissue culture)
- cells are scraped from the parent plant (explants)
- surface of explants are sterilised using a disinfectant
- then are transferred to a sterile petri dish containing nutrient agar
- the growth median encourages the explant cells to grow and divide into small masses of cells (callus)
- each callus is transferred to a fresh growth medium that contains a range of plant growth regulators (hormones)- causes the callus to develop roots, stems and leaves- forming a plantlet
- plantlets can be transferred to individual potting trays and develop into plants
what are the two different ways to clone plants
- cuttings
- micropropagation/ tissue culture (mass production)
what are the advantages of micropropagation
- clones are genetically identical individuals
- allows a variety of plant with desirable characteristics to be produced (cheaply, with greater yield, quickly, at any time of the year, identical and disease free (or resistant plants can be bred))
what are the disadvantages of micropropagation
- trained personnel and a sterile laboratory are required
- all plants produced are genetically identical- so vulnerable to the same diseases and pests (lack of genetic variation makes them less able to adapt to environmental change)
what is ‘in vitro’
- ‘outside a living organism’
- how explants are grown
describe the process of embryo cloning for a cow
- egg cells from the best cow are artificially fertilised using sperm cells taken from the best bull- forms an embryo
- the developing embryo is then split apart many times before it becomes specialised
- forms many separate, genetically identical embryos
- these cloned embryos are then transplanted into host mothers
describe the process of adult cell cloning
- the nucleus is removed from an unfertilised egg cell (enucleated)
- the nucleus from an adult diploid body cell is inserted into the egg cell
- fused together by an electric shock
- divides by mitosis
- embryo is then implanted into the uterus of a surrogate mother
what are the benefits of cloning
- can help preserve endangered species or resurrect extinct animals
- makes it possible to quickly and cheaply produce commercial quantities of consistently high quality plants at any time of the year
- allows farmers to increase yield by using high quality livestock and plants
what are the risks of cloning
- results in a lack of genetic diversity- makes them more vulnerable to disease or changes in environment
- evidence that cloned animals may not be as healthy as normal ones
- ethical concerns (people believe its unethical, has a high rate of failure)
what is a clone
- a genetically identical copy of an organism
- can be produced through asexual reproduction, micropropagation techniques, or somatic cell nuclear transfer
