Use of Biological Resources - GCSE Flashcards
what is a plant’s rate of photosynthesis affected by?
- the amount of light
- the amount of carbon dioxide
- the temperature
why do plants do photosynthesis?
they do it in order to make food for themselves and grow
how can photosynthesis be helped?
by artificially creating the ideal conditions in glasshouses or polytunnels
why is keeping plants enclosed in a glasshouse better?
there are 5 looong points
- easier to keep them free from pests and diseases
- helps farmers control the water supplied to their crops
- traps the Sun’s heat to keep the plants warm. In winter farmers might even use heaters to keep temperature at an ideal level
- farmers often supply artificial light after the Sun goes down to give their plants more time to photosynthesise
- farmers can increase the level of carbon dioxide in glasshouse
why is it a good idea to put your plants inside a glasshouse?
because in a glass house you will be able to control the conditions your plants are living in.
for example: by increasing the temperature and CO2 concentration and amount of light available a farmer can increase the rate of photosynthesis. This means the plants will grow bigger and faster (and crop yields will be higher)
why do plants need certain minerals?
to make important compounds like proteins
what happens if plants don’t get enough minerals?
their growth and life process are affected
why are minerals sometimes missing from the soil?
because they’ve been used up by a previous crop
why do farmers use fertilisers?
to replace these missing minerals or provide more of them. This helps to increase the crop yield
what are pests?
they are microorganisms, insects or mamals that eat crops
what is the advantage of killing pests?
fewer plants are damaged or destroyed, increasing crop yield
what is crop yield?
Crop yield is a standard measurement of the amount of agricultural production
what is pesticides?
it is a form of chemical pest control. They are often poisonous to humans so they must be used carefully. It can also be harmful to other wildlife
what is biological control?
it is an alternative to using pesticides. It means using other organisms to reduce the numbers of pests either by encouraging wild organisms or adding new ones
what are good organisms to use for killing pests? (biological control)
- predators
- parasites
- disease-causing
why is biological control considered better than pesticides?
- has a longer lasting effect
- less harmful to wildlife
why can biological control be bad sometimes? Give an example
because introducing new organisms can cause problems
eg. cane toads were introduced to Australia to eat beetles, but they are now a major pest themselves because they poison the native species that eat them
what is fermentation?
it is when microorganisms break sugars down to release energy, usually by anaerobic respiration.
what is yoghurt?
fermented milk
how do you make yoghurt?
there are 6 steps
1) the equipment is sterilised to kill off any unwanted microorganisms
2) milk is pasteurised (heated up to 72 degrees for 15 seconds) to kill any harmful microorganisms. Then the milk’s cooled
3) lactobacillus bacteria are added and the mixture is incubated (heated to about 40 degrees) in a vessel called a fermenter
4) the bacteria ferment the lactose sugar in the milk to form lactic acid
5) lactic acid causes the milk to clot, and solidify into yoghurt
6) finally, flavours and colours are sometimes added and the yoghurt is packaged
what really useful stuff can microorganism (like bacteria) make?
penicillin or insulin
in industry, where are microorganisms grown?
in a large containers called fermenters. The fermenter is full of liquid ‘culture medium’ in which microorganisms can grow and reproduce
how are the conditions inside the fermentation vessels?
they are kept at the optimum (best) levels for growth. This means the yield of products from the microorganisms can be as big as possible
how is the pH in fermenters?
it is monitored and kept at the optimum level for the microorganisms’ enzymes to work efficiently. This keeps the rate of reaction and product yield as high as possible
how do fermenters get the nutrients?
the nutrients needed by the microorganisms for growth are provided in the liquid culture medium
how are microorganisms on fermenters?
they are kept in contact with fresh medium by paddles that circulate (or agitate) the medium around the vessel. This increases the product yield because microorganisms can always access the nutrients needed for growth.
how is temperature on fermenters?
it is monitored and kept at an optimum level. A water-cooled jacket makes sure it doesn’t get so hot that the enzymes denature
how are the vessels on fermenters?
sterilised between uses with superheated stem that kills unwanted microbes. Having aseptic conditions increases the product yield because the microorganisms aren’t competing with other organisms, it also ensures that the product doesn’t get contaminated
what happens if the microorganisms need oxygen for respiration on fermenters?
oxygen is added by pumping in sterile air. This increases the product yield because microorganisms can always respire to provide the energy for growth
what happens when yeast respires aerobically?
it breaks down sugar into CO2 and water
when is yeast used?
it’s used in baking where it’s mixed into dough to create bubbles of CO2 that make the dough rise
(basically we use yeast to make bread)
how is bread made? (think about: why is yeast an important part of the process?)
(9 very, very, loooog steps)
1) bread dough is made by mixing yeast with flour, water and a bit of sugar
2) the dough is then left in a warm place to rise, this happens with the help of the yeast
3) enzymes break down the carbohydrates in the flour into sugars
4) the yeast then uses these sugars in aerobic respiration, producing carbon dioxide
5) when the oxygen runs out, the yeast switches to anaerobic respiration. This is also known as fermentation, and produces carbon dioxide and alcohol (ethanol)
6) the carbon dioxide produced is trapped in bubbles in the dough
7) these pockets of gas expand and the dough begins to rise
8) the dough is then baked in an oven, where the yeast continuous to ferment until the temperature of the dough rises enough to kill the yeast. Any alcohol produced during anaerobic respiration is boiled away
9) as the yeast dies, the bread stops rising, but pockets are left in the bread where the carbon dioxide is trapped
what experiment do you do to investigate the change in rate of CO2 production by yeast during anaerobic respiration when temperature changes?
(there are 8 steps and unfortunately they are long ):)
1) mix together sugar, yeast and distilled water, then add the mixture to a test tube
2) to create anaerobic conditions, add a layer of oil to the top of the yeast mixture. This will prevent oxygen from the air getting into the mixture
3) attach a bung with a tube leading to a second test tube of water
4) place the tube containing the yeast mixture in a water bath at a certain temperature
5) leave the tube to warm up a bit and then count how many bubbles are produced in a given period of time
6) calculate the rate of CO2 production by dividing the number of bubbles produced by the time taken for them to be produced in seconds. This gives an indication of respiration rate
7) repeat the experiment with the water bath set at a different temperature
8) respiration is controlled by enzymes, so as temperature increases, so should the rate of respiration (until its optimum temperature)
what is selective breeding?
is mating the best organisms together, the best features
what are some characteristics in organisms that cause them to be selectively breed?
- maximum yield of meat, milk, grain etc
- good health and disease resistance
- temperament, speed, fertility, good mothering skills, etc.
- in plants other qualities like attractiveness, nice smell, etc.
what are the 4 basic process involved in selective breeding?
- from your existing stock select the ones which have the best characteristics.
- breed them with each other
- select the best offspring and breed them together
- continue this process over several generations, and the desirable trait gets stronger and stronger. It will give the farmer better and better yields
mating cows and bulls naturally can be difficult, so what is another solution to this problem?
artificial insemination
why is artificial insemination considered a good option?
because it is safer for the cow, quicker and cheaper to transport semen than bulls. The semen cal also be used to impregnate multiple cows, and can be stored after the bull has died.
what is the result of selective breeding in sheep?
farmers can selectively breed sheep to increase the number of lambs born
how are the sheep and rams chosen for the selective breeding process?
female sheep who produce large numbers of offspring are bred with rams whose mothers had large numbers of offspring. These characteristics is then passed on to the next generations
what other than sheep and cow is selective breeding also applied to?
it is applied to increase crop yield
give an example of selective breeding being used to increase crop yield:
- tall wheat plants have a good grain yield but are easily damaged by wind and rain.
- dwarf wheat plants can resist wind and rain but have a lower grain yield
- -> these two types of wheat plant were cross-bred and the best resulting wheat plants were cross-bred again. This results in a new variety. Now these plants can resist to bad weather and have a high grain yield
what are ligase enzymes used for?
they are used to join two pieces of DNA together
what are two different bits of DNA stuck together known as?
they are known as recombination DNA
what do restriction enzymes do?
they recognise specific sequences of DNA and cut the DNA at these points
what is a vector?
it is something that’s used to transfer DNA into a cell
what are the two sorts of vectors?
plasmids and viruses
what are plasmids?
they are small, circular molecules of DNA that can be transferred between bacteria
what do viruses do?
viruses insert DNA into the organisms they infect
describe the whole process of genetic engineering:
im so sorry but there are 6 steps
1) the DNA you want to insert is cut out with a restriction enzyme. The vector DNA is then cut open using the same restriction enzyme.
2) the vector DNA and the DNA you’re inserting are mixed together with ligase enzymes
3) the ligases join the two pieces of DNA together to produce recombinant DNA
4) the recombinant DNA is inserted into other celss
5) these cells can now use the gene you inserted to make the protein you want
6) bacteria that contian the gene for human insulin are transgenic (meaning they contain genes transferred from another species)
what can genetically modified plants improve?
food production
what does making crops insect-resistant mean?
it means farmers don’t have to spray as many pesticides so wildlife that doesn’t eat crop isn’t harmed. It also increases crop food, making more food
what are the ways to genetically modify crops to increase production?
- make them resistant to insects
- make them resistant to herbicides (chemicals that kill plants)
what does making crops herbicide-resistant mean?
it means farmers can spray their crops to kill weeds, without affecting the crop itself. This increases crop yield
what are the concerns about growing genetically modified crops?
- transplanted genes may get out into the environment
- genetically modified crops could adversely affect food chains or even human health
why are some people against genetic engineering?
they worry that changing an organism’s genes might create unforeseen problems - which could then get passed on to future generation.
