topic 15 - biological resources Flashcards
4 features of glasshouses and how they increase rate of photosynthesis
- artificial heating - enzymes controlling photosynthesis work faster
- artificial lighting - plants photosynthesise for longer
- increased CO2 content - plants photosynthesise faster
- regular watering - easy access to water
3 features of polythene tunnels and how they increase rate of photosynthesis
- large plastic tunnel - shields crops from extreme weather
- increased temperature inside - enzymes work faster for photosynthesis
- prevent entry of pests - these could damage and eat the crops
3 limiting factors
- temperature
- CO2 concentration
- light intensity
how does temperature affect rate of photosynthesis
- as temperature increases the rate of photosynthesis increases as the reaction is controlled by enzymes
- However, as the reaction is controlled by enzymes, this trend only continues up to a certain temperature beyond which the enzymes begin to denature and the rate of reaction falls to 0
how does light intensity affect rate of photosynthesis
- The more light a plant receives, the faster the rate of photosynthesis
- This trend will continue until some other factor required for photosynthesis prevents the rate from increasing further because it is now in short supply
how does CO2 concentration affect rate of photosynthesis
- This means the more carbon dioxide that is present, the faster the reaction can occur
- This trend will continue until some other factor required for photosynthesis prevents the rate from increasing further because it is now in short supply
what are fertilisers
fertilisers increase the amount of key nutrients in the soil for crop plants, meaning that they can grow larger and are more healthy, which increases yields
what are pesticides
these chemicals kill off unwanted insects and weed species, meaning that there is less damage done to crop plants by insects, as well as reducing competition from other plant species, which increases yields
3 mineral ions required in plants
- nitrogen
- potassium
- phosphorus
why is nitrogen needed in plants and what is it absorbed as and impacts of lacking
- absorbed as nitrates
- Needed to make amino acids which are the building blocks of proteins
- Lack of nitrogen causes weak growth and yellowing of the leaves of plants
why is potassium needed in plants and what is it absorbed as and impacts of lacking
- Absorbed in the form of nitrates
- Needed to make amino acids which are the building blocks of proteins
- Lack of nitrogen causes weak growth and yellowing of the leaves of plants
why is phosphorus needed in plants and what is it absorbed as and impacts of lacking
- Absorbed in the form of phosphates
- Needed to make DNA and cell membranes
- lack of phosphorus can cause poor root growth and discoloured leaves
3 kinds of pesticides
Insecticides kill insect pests
Herbicides kill plant pests
Fungicides kill fungal pests
3 advantages of pesticides
- easily accessible & cheap
- have immediate effect
- kill the entire population of pests
4 disadvantages of pesticides
- pests can develop a resistance to them
- non-specific to the pest so can kill other beneficial organisms
- they can be persistent chemicals and lead to great accumulation at the top of the food chain
- need to be repeatedly applied
what is biological control
using a natural predator to eat the pest species and therefore reduce the impact of the pest on crop yields
5 advantages of biological control
- natural method - no pollution
- no resistance
- can target specific species
- long lasting
- doesn’t need to be repeatedly applied
5 disadvantages of biological control
- may eat other organisms instead of the pest
- takes a longer period of time to be effective
- cannot kill the entire population
- may not adapt to new environment and leave
- may become a pest themselves
features of a basic fungal cell
- nucleus
- cell membrane
- ribosomes
- cell wall of chitin
- cytoplasm
- mitochondria
how is bread made
- During bread making yeast is added to bread dough
- The yeast produces enzymes that break down the starch in flour, releasing sugars that can be used by the yeast in respiration
- The yeast begin to respire aerobically but will switch to anaerobic respiration when oxygen runs out
- When yeast carries out anaerobic respiration it produces alcohol (ethanol) and carbon dioxide
- The carbon dioxide produced by the yeast is trapped in small air-pockets in the dough, causing the dough to rise (increase in volume)
- The dough is then baked in a hot oven to form bread
- During baking any ethanol produced by the yeast is evaporated in the heat, so bread doesn’t contain any alcohol
- The yeast is killed by the high temperatures used during baking
- This ensures there is no further respiration by the yeast
practical: method for investigating anaerobic respiration in yeast
- Mix yeast with sugar solution in a boiling tube
- The sugar solution provides the yeast with glucose for anaerobic respiration
- Carefully add a layer of oil on top of the solution
- This prevents oxygen from entering the solution (prevents aerobic respiration in the yeast)
- Using a capillary tube, connect this boiling tube with another boiling tube that is filled with limewater
- Place the boiling tube with yeast and sugar solution into a water bath at a set temperature and count the number of bubbles produced in a fixed time (e.g. 2 minutes)
- The rate that carbon dioxide is produced by yeast can be used to measure the rate of anaerobic respiration (i.e. the rate of fermentation)
- Change the temperature of the water bath and repeat
- Compare results at different temperatures to find out at which temperature yeast respires fastest
- The higher the temperature, the more bubbles of carbon dioxide should be produced as higher temperatures will be closer to the optimum temperature of enzymes in yeast, increasing enzyme activity
- As respiration is an enzyme controlled reaction, as enzyme activity increases the rate of anaerobic respiration will increase
- If the temperature is too high (beyond the optimum temperature), the enzymes will denature causing carbon dioxide production to slow down and eventually stop
bacteria in yoghurt
Lactobacillus
how to make yoghurt
- First, all equipment is sterilised to kill other, unwanted bacteria and to prevent chemical contamination
- Milk is then pasteurised (heated) at 85-95°C to kill other, unwanted bacteria
- The milk is then cooled to 40-45°C and Lactobacillus bacteria is added
- The mixture is incubated at this temperature for several hours, while the Lactobacillus bacteria digest milk proteins and ferment (digest) the sugar (i.e. the lactose) in the milk
- The Lactobacillus bacteria convert the lactose into lactic acid and this increased acidity sours and thickens the milk to form yoghurt
- This lowering of the pH also helps to prevent the growth of other microorganisms that may be harmful, so acts as a preservative
- The yoghurt is then stirred and cooled to 5°C to halt the action of the Lactobacillus bacteria
2 industries yeast is most used in
- baking
- brewing
what’s a fermenter
containers used to grow (‘culture’) microorganisms like bacteria and fungi in large amounts
why and how to control aseptic precautions
Fermenter is cleaned by steam to kill microorganisms and prevent chemical contamination, which ensures only the desired microorganisms will grow
why and how to control nutrients
Nutrients are needed for use in respiration to release energy for growth and to ensure the microorganisms are able to reproduce
why and how to control optimum pH
pH inside the fermenter is monitored using a probe to check it is at the optimum value for the particular microorganism being grown. The pH can be adjusted, if necessary, using acids or alkalis
why and how to control optimum temperature
Temperature is monitored using probes and maintained using the water jacket to ensure an optimum environment for enzymes to increase enzyme activity (enzymes will denature if the temperature is too high or work too slowly if it is too low)
why and how to control oxygenation
Oxygen is needed for aerobic respiration to take place
why and how to control agitation
Stirring paddles ensure that microorganisms, nutrients, oxygen, temperature and pH are evenly distributed throughout the fermenter
what is selective breeding
selecting individuals with desirable characteristics and breed them together
features that may be bred for in plants
- Disease resistance in food crops
- Increased crop yield
- Hardiness to weather conditions (e.g. drought tolerance)
- Better tasting fruits
- Large or unusual flowers
selective breeding drawbacks
- Selective breeding can lead to ‘inbreeding’ as only the ‘best’ animals or plants (which are closely related to each other) are bred together
- This results in a reduction in the gene pool – this is a reduction in the number of alleles (different versions of genes) in a population
- an increased chance of:
—> Organisms inheriting harmful genetic defects
—> Organisms being vulnerable to new diseases (there is less chance of resistant alleles being present in the reduced gene pool)
traits that animals may be bred for
- Cows, goats and sheep that produce lots of milk or meat
- Chickens that lay large eggs
- Domestic dogs that have a gentle nature
- Sheep with good quality wool
- Horses with fine features and a very fast pace
differences between natural selection and selective breeding
- occurs naturally, only occurs with human intervention
- Results in development of populations with features that are better adapted to their environment and survival, Results in development of populations with features that are useful to humans and not necessarily useful to the survival of the individual
- takes a long time, doesnt take long
how does selective breeding occur
- individuals with best characteristics chosen
- they are bred together
- new generation has even better characteristics
- process repeats, creating even better generations
what is genetic modification
Genetic modification involves the transfer of a gene or section of DNA from one organism into the DNA of another organism
what are restriction enzymes
Restriction enzymes are used to cut the required gene out of the DNA
how do restriction enzymes work
- Restriction enzymes are used to cut the required gene out of the DNA
- Different types of restriction enzymes cut the DNA in different locations (they target different sequences of DNA).
- This means that specific enzymes can be selected that will cut out the required piece of DNA
- Cutting DNA with restriction enzymes results in pieces of DNA with ‘sticky ends’
- Sticky ends are short sections of single-stranded DNA; they are ‘sticky’ because they will pair together with another sticky end that contains complementary bases
- A bacterial plasmid is cut by the same restriction enzyme
- This ensures that the base pairs of the two sticky ends are complementary to each other, meaning that they will ‘stick’ together
- The plasmid and the isolated gene are joined together by DNA ligase enzyme
- If two pieces of DNA have complementary sticky ends, DNA ligase will link them to form a single, unbroken molecule of DNA
- The plasmid is transfected into bacteria. the bacterial are then left to grow and reproduce with each generation containing the recombinant plasmid
- the bacteria will express the gene that has been inserted and make the protein that it codes for. e.g. they will all be producing human insulin
how to produce insulin from GM bacteria
- gene for insulin production is located within a human chromosome
- Restriction enzymes are used to isolate the human insulin gene, leaving it with ‘sticky ends’ (a short section of unpaired bases)
- A bacterial plasmid is cut by the same restriction enzyme leaving it with corresponding sticky ends
- The plasmid and the isolated human insulin gene are joined together by DNA ligase enzyme
- If two pieces of DNA have matching sticky ends, DNA ligase will link them to form a single, unbroken molecule of DNA
- The genetically engineered (recombinant) 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. All the new bacteria will express the human insulin gene and make the human insulin 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
3 advantages of GM crops
- reduced use of chemicals
- cheaper & less time consuming
- increased yields from crops
what does transgenic mean
the transfer of genetic material from one species to a different species
If an organism contains DNA from a different species it is called a transgenic organism
5 disadvantages of GM crops
- increased cost of seeds
- increased dependency on certain chemicals
- Risk of inserted genes being transferred to wild plants by pollination
- reduced biodiversity
- dont grow as well as non GM crops
