Section 9 - Use of Biological Resources P1 Flashcards
What affects a plants rate of photosynthesis?
- intensity of light
- concentration of carbon dioxide
- the temperature
How can you maximise crop yield?
By carefully controlling the conditions which plants are grown in since they make food for themselves
-increasing the temperature, carbon dioxide concentration and light intensity
What buildings do we use to grow crops to artificially create ideal conditions for photosynthesis?
-glasshouses or polytunnels (big tube-like structures made from polythene
Why is it easier to enclose plants in structures than letting them grow in a natural environment?
- keeping the plants enclosed in a glasshouse makes it easier to keep them free from pests and disease
- helps farmers control the water supplied to their crops
What do commercial farmers often do about the crops access to light?
-often supply artificial light after the sun goes down to give the plants more time to photosynthesise
What do commercial farmers often do about the crops growing environment’s temperature?
- glasshouses trap the sun’s heat to keep the plants warm
- in winter, a farmer might use a heater to keep the temperature at an ideal level
What do commercial farmers often do about the crops access to carbon dioxide?
-farmers can increase the level of carbon dioxide in glasshouses (e.g. by using a paraffin heater to heat the place, as it burns it create carbon dioxide as a by-product)
What minerals do plants need?
nitrogen, potassium, phosphorus, magnesium
-so they can make important compounds
What happens if a plant doesn’t get enough of the mineral ions it needs?
Their growth and life processes can be affected
What can cause the soil to not have enough of the minerals needed by plants?
-a previous crop could have used them up
How and why do farmers increase the levels of mineral ions in the soil?
- use fertilisers to replace the missing mineral ions or provide more of them
- helps to increase crop yield
What are pests?
Pests include microorganisms, insects and mammals.
Pests are organisms that do unhelpful things, such as feeding on crops?
What do farmers do about pests?
Pests that feed on crops are killed using methods of pest control.
Why do farmers want to control pests?
If pests are killed, then fewer plants are damaged or destroyed, increasing crop yield
What methods of pest control do farmers use?
pesticides
biological control
What are pesticides?
Pesticides are a form of chemical pest control
What are the dangers of using pesticides?
- often poisonous to humans (must be used carefully to keep the level of pesticide in food below a safe level)
- some pesticides can harm other wildlife
What is biological control?
Biological control means using other organisms to reduce the numbers of pests, either by encouraging wild organisms or adding new ones
What types of organisms can be used for biological control?
- predators(ladybirds eat aphids)
- parasites(some flies lay their eggs on slugs, eventually killing them)
- disease-causing(bacteria that affect caterpillars)
What are the advantages of using biological control?
- can have a longer-lasting effect than spraying pesticides
- can be less harmful to wildlife
What are the disadvantages of using biological control?
-they can upset a balance, or the new organism introduced can become a pest itself (e.g. cane toads were introduced to Australia to eat beetles, now they are a major pest because they poison the native species that eat them)
What is fermentation?
Fermentation is when microorganisms break sugars down to release energy - usually by anaerobic respiration.
What is fermented milk?
Yogurt
Why is the equipment used to ferment the milk sterilised?
To kill of any unwanted microorganisms
Describe the process by which milk is turned into yogurt:
- the equipment is sterilised
- the milk is pasteurised, then cooled
- lactobactillus bacteria are added, the mixture is incubated (around 40°C) in a fermenter vessel
- the bacteria ferment the lactose into lactic acid
- lactic acid causes the milk to clot & solidify into yogurt
- flavours and colours are sometimes added to the yogurt and it is packaged
What does the pasteurising process involve?
heating milk up to 72°C for 15 seconds
Why is milk pasteurised in the process for making yogurt?
To kill any harmful, unwanted microorganisms
What do the bacteria do to the milk during fermentation?
The bacteria ferment the lactose sugar in the milk to form lactic acid
What useful things can microorganisms be used to make?
penicillin or insulin
How are microorganisms grown in industry?
Grown in large containers called fermenters
What does a fermenter contain?
- liquid ‘culture medium’ in which microorganisms can grow and reproduce
- conditions are kept at optimum levels for growth (the yield of the products from the microorganism is maximised as much as possible)
In a fermenter, how are nutrients needed for the microorganisms growth provided?
they are provided in the liquid culture medium
In a fermenter, what conditions are maintained?
- pH monitored
- nutrients needed for growth of microorganisms
- the temperature
- oxygen for respiration
- paddles to circulate the medium
- vessels are sterilised
In a fermenter, why is the pH monitored?
To keep it at an optimum level for the microorganisms enzymes to work efficiently
-keeps the rate of reaction and product yield as high as possible
In a fermenter, why is temperature monitored?
Temperature is monitored and kept at an optimum level
In a fermenter, how is temperature controlled in a fermenter?
a water-cooled jacket makes sure it doesn’t get so hot that the enzymes denature (since heat is produced from the respiration)
In a fermenter, why do they have paddles?
Microorganisms 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
In a fermenter, why is oxygen provided?
Microorganisms need oxygen for respiration, it is added by pumping in sterile air
-increases the product yield because microorganisms can always respire to provide the energy for growth
In a fermenter why are vessels sterilised between uses?
Sterilised with a superheated steam that kills unwanted microbes
-aseptic conditions increases the product yield because microorganisms aren’t competing with each other and the product doesn’t get contaminated
What is bread dough made up of?
yeast
flour
water
a bit of sugar
Describe how yeast is used to make bread:
- the dough is made and left in a warm place to rise
- the yeast respires aerobically until oxygen runs out, it then respires anaerobically (this is fermentation, and produces CO₂ and ethanol)
- CO₂ produced is trapped in bubbles in the dough
- these pockets of gas expand and the dough rises
- the dough is baked in the oven, the yeast continues to ferment until the temperature kills the yeast
- alcohol produced is boiled away
- when the yeast dies, the bread stops rising but the pockets are left where CO₂ was trapped
How does yeast cause bread dough to rise?
- enzymes break down carbohydrates in the flour into sugars which the yeast uses for respiring in aerobic respiration and producing CO₂
- the yeast respires aerobically until the oxygen runs out, then it respires anaerobically (this is fermentation, and produces CO₂ and ethanol)
- CO₂ produced is trapped in bubbles in the dough
- these pockets of gas expand and the dough rises
How can you experiment the rate of CO₂ production by yeast during anaerobic respiration changes under different conditions?
- Mix yeast, sugar and distilled water
- place it in a test tube with a bung and delivery tube on which is connected to another test tube with water in, which you can count the number of bubbles produced
Describe a practical for how different conditions affect respiration rate of yeast:
THIS IS FOR CHANGING TEMPERATURE, COULD ADAPT IT FOR OTHER CONDITIONS
- mix sugar, yeast, distilled water, add to a test tube
- attach a bung with a delivery tube to another test tube with water in
- place the tube containing the yeast in a water bath
- let the tube acclimatise for 5 mins, then count how many bubbles that are produced in 5 mins
- calculate the rate of CO₂ production by dividing the number of bubbles by the time taken(in secs) - this gives an indication of the respiration rate
- repeat the experiment with different water bath temperatures
For a practical of how different conditions affect respiration rate of yeast, why would you seal the test tubes with bungs?
To stop oxygen getting in, so the yeast will have to respire anaerobically
What is respiration controlled by?
Respiration is controlled by enzymes, so as temperature increases, so should the rate of respiration up to the optimum temperature
How can you measure gas produced in an experiment more accurately than counting bubbles?
Using a gas syringe so you’d measure the volume of gas produced
Why are organisms selectively bred?
To develop the most desired features
-selective breeding is also know as artificial selection
What are the desired feature wanted from selective breeding?
- maximum yield of meat, milk, grain…
- good health and disease resistance
- in animals qualities such as temperament, speed, fertility, good mothering skills…
- in plants qualities such as attractive flowers, nice smell…
What is the basic process of artificial selection?
- from your existing stock select the ones with the best characteristics
- breed them with each other
- select the best of the offspring and breed them together
- continue this process over several generations, the desirable traits get stronger and stronger (in farming yields will get better and better)
How can selective breeding increase the productivity of cows?
- cows can be selectively bred (for meat, milk..)
- the animals with characteristics that will enhance the characteristics are selected and bred together
- the offspring with the best characteristics are selected and bred together
- continued over several generations to improve the desired characteristic
- cows can be impregnated naturally or by AI
What is AI?
Artificial insemination can be used because mating cows and bulls can be difficult
- it is safer for the cow and much quicker and cheaper to transport bull semen than bulls
- this semen can be used to impregnate multiple cows and can be stored after the bull has died
How can selective breeding increase the number of offspring in sheep?
- farmers can selectively breed sheep to increase the number of lambs born
- ewes who have large numbers of offspring are bred with ram whose mothers had large numbers of offspring
- characteristics of having large numbers of offspring is passed on to the next generation
How can selective breeding increase crop yield?
- selective breeding can be used to combine two desired characteristics
- tall wheat plants (have good grain yield, but are easily damaged by rain and wind), dwarf wheat plants (resist rain and wind, but have a lower grain yield)
- the two types were cross bred and their best offspring bred together as well, resulting in a new variety of wheat (dwarf wheat plants which could resist weather and have a high grin yield)
What do restriction enzymes do?
Restriction enzymes recognise specific sequences of DNA and cut the DNA at these points
What do ligase enzymes do?
Ligase enzymes are used to join two pieces of DNA together
What is recombinant DNA?
Two different bits of DNA stuck together
What enzymes are involved with DNA being cut up and joined together?
Restriction enzymes and ligase enzymes
What is a vector?
A vector is something that’s used to transfer DNA into a cell
What are the two types of vectors?
plasmids
viruses
What are plasmids?
Plasmids are small, circular molecules of DNA that can be transferred between bacteria
What do viruses do as a vector?
Viruses insert DNA into the organism they infect
Describe how genetic engineering works:
- DNA you want to insert(e.g. gene for human insulin) is cut out using a restriction enzyme, the vector DNA is then cut out using the same restriction enzyme
- the vector DNA mixes with the inserted DNA with ligase enzymes
- ligase joins them to form recombinant DNA
- recombinant DNA is inserted into other cells(e.g. Bacteria)
- these cells now use the gene you inserted to make the protein you want (e.g. Bacteria cells producing human insulin for people with diabetes)
What does transgenic mean?
Organisms that contain genes transferred from another species
(e.g. bacteria that contain the gene for human insulin)
What are some of the ways crops can be genetically modified to increase food production?
- to make them resistant to insects
- to make them resistant to herbicides (chemicals that kill plants)
What is the advantage of farmers making insect-resistant plants?
-farmers don’t have to spray as many pesticides, so wildlife that doesn’t eat the crop isn’t harmed and it increases crop yield making more food
What is the advantage of farmers making herbicide-resistant plants?
-farmers can spray their crops to kill weeds, without affecting the crop itself, increasing crop yield
What are the concerns about growing genetically modified plants?
- transplanted genes might get out into the environment
- genetically modified crops could adversely affect food chains or even human health
Why are some people against genetic engineering altogether?
-they worry that changing an organism gene might create unforeseen problems, which could then get passed on to future generations
