Topic 9 - Use of Biological Resources

• Describe how GLASSHOUSES and POLYTHENE tunnels can be used to increase the yield of certain crops

  - all conditions can be controlled by the farmer: light, temperature, CO2, supply of water

  
  

  LIGHT:

  - transparent material allows more light in for photosynthesis

  - extra lighting can be added in winter/darker periods

  
  

  TEMPERATURE:

  - using heaters --> optimum temp for enzymes controlling photosynthesis

  - higher temperature due to greenhouse effect

  - ventilation to release hot air is possible (avoid enzyme denaturing)

  
  

  CARBON DIOXIDE:

  - when you burn fuels for temperature it also releases carbon dioxide as waste --> increases levels of CO2

  
  

  WATER:

  - heaters also increase water vapour levels in the air

  - less water lost by plant in transpiration

  - control water/humidity very well

  
  

  Prevent entry of pests (enclosed space)
• Fertilisers

  Increase amount of key nutrients (nitrogen, potassium, phosphorus) in soil for crop plants = increasing crop yield as plants can grow healthily

  - crops take up these minerals from the soil so if the crops are grown repeatedly in the same field, the mineral ions need to be replenished

  
  

  ORGANIC:

  - manure and compost

  - no chemicals = good for environment

  - not efficient at farmers can't control mineral content

  
  

  CHEMICAL:

  - carefully formulated chemicals containing minerals

  - can control + be spread evenly

  - but leads to EUTROPHICATION + the manufacturing results in burning of fossil fuels
• Pest control

  Pests like insects can damage crops by eating them

  (eg. fungi can infect crop plants + spread disease)

  
  

  CHEMICAL CONTROL: PESTICIDES

  pros:

  - easy to access

  - cheap

  - kills entire population of pests

  - immediate effect

  cons

  - organisms can develop resistance

  - need to be repeatedly applied

  - imbalance food chain

  
  

  BIOLOGICAL CONTROL: SPECIES

  - species introduced (preys to pests) --> ladybirds feed on whiteflies + aphids

  - do NOT completely remove pests (just decrease lvls)

  pros:

  - no pollution

  - no resistance

  - can target specific species

  - long lasting

  - no need to re-apply

  cons:

  - may eat other organisms instead of pests

  - take long time to be effective

  - cannot kill ENTIRE population

  - may become pest itself

  - damage food chain
• Nitrogen

  - absorbed in form of nitrates

  - used to make amino acids (to make protein)

  lack = weak growth, yellowing of leaves
• Phosphorous

  - phosphates absorbed

  - make DNA + cell membranes

  lack = poor root growth, discoloured leaves (purple)
• Potassium


  - allows enzyme reactions to take place to produce ATP in respiration

  - needed for enzymes involved in photosynthesis

  lack = discoloured leaves, poor fruit growth
• what type of pesticide kills insects

  insecticide
• what type of pesticide kills plant pests

  herbicide
• what type of pesticide kills fungal pests

  fungicides
• Yeast in food production

  - microorganism

  Anaerobically = and ethanol + carbon dioxide is produced), sugar is broken down into CO2 + H2O

  • Anaerobically = ethanol + carbon dioxide is produced
• Anaerobic respiration in yeast equation

  C6H12O6 -> 2C2H6O + 2CO2

  Glucose -> Alcohol + carbon dioxide
• understand the effects on crop yield of increased carbon dioxide and increased temperature in glasshouses

  CARBON DIOXIDE:

  - paraffin lamps are used to increase CO2 levels

  - more photosynthesis takes place --> plants grow bigger --> increase crop yield

  - only up to a certain point, then it will plateau

  
  

  TEMPERATURE:

  - enclosed

  - heat from Sun can be trapped

  - temperature reaches optimum --> rate of photosynthesis increases --> increasing crop yield

  - however, above optimum, enzymes will denature --> photosynthesis will decrease and so will crop yield
• what is used in glasshouses to increase CO2 levels?

  paraffin lamps
• Practical: investigate the role of anaerobic respiration by yeast in different conditions

  fermentation = how a microorganism obtains its energy with no oxygen

  - it does this by using certain substances e.g. sugars and turning them into waste products

  1. paraffin oil to keep oxygen getting to yeast

  2. sugar (glucose) and yeast solution

  3. hydrogencarbonate indicator or lime water to detect CO2

  
  

  variables and conditions to see how it affects rate of reaction:

  - temperature

  - amount of yeast

  - type yeast

  - pH

  - concentration of glucose
• Role of bacteria (Lactobacillus) in the production of yoghurt

  Yoghurt is fermented milk

  1. equipment sterilised to kill other UNWANTED bacteria + prevent chemical contamination

  2. milk is pasteurised (heated) to kill other UNWANTED bacteria (contamination with other bacteria could slow production of yoghurt by competing with the lactobacillus for the lactose food)

  3. Milk is cooled (does not kill lactobacillus)

  4. Lactobacillus bacteria is added. mixture is incubated at 40°C for hours until the bacteria digests milk proteins + ferment (digest) the sugar (lactose) in the milk

  5. lactose sugar --> lactic acid (increases acidity + sours + thickens milk). lowering pH prevents growth of other microorganisms - preservative

  6. yoghurt is stirred and cooled to HALT THE ACTION OF THE LACTOBACILLUS BACTERIA

  
  

  Bacteria called LACTOBACILLUS
• Fermentation

  when microorganisms break sugars down to release energy (usually by anaerobic respiration)
• What is the sugar being fermented when milk gets turned into yoghurt?

  lactose
• what is lactose sugar turned into?

  lactic acid
• Industrial fermenters

  - containers used to grow microorganisms like bacteria + fungi in large amounts

  - used for: brewing beer, yoghurt making

  
  

  controlling conditions to produce exact quantities of the microorganism:

  - ASEPTIC PRECAUTIONS - fermenters cleaned by steam to kill unwanted microorganisms and prevent chemical contamination

  - NUTRIENTS - needed for respiration to release energy for growth + ensure microorganisms are able to reproduce. PADDLES are used to circulate the nutrients around the vessel

  - OPTIMUM TEMP - maintained using water jacket to ensure optimum temp for enzyme activity. monitored using probes

  - OPTIMUM pH - monitored using probes to ensure enzyme activity at highest rate. adjusted using acids/alkalis

  - OXYGENATION - needed for aerobic respiration to take place so energy is generated for growth. pump in sterile air

  - AGITATION - stirring paddles ensure microorganisms, nutrients, oxygen, temp, pH are evenly distributed
• Selective breeding in plants - best features

  develop best features:

  - disease resistant crops

  - high demand crops

  - increase crop yield

  - better tasting fruit

  - better suited for environment / climate

  - better looking flowers
• example of selective breeding in plants

  WILD BRASSICA - cauliflower, cabbage, broccoli
• selective breeding in plants - PROBLEMS

  can lead to inbreeding

  - occurs when the "best" plants (that are CLOSELY related) are bred together

  - results in reduction in gene pool (reduction in number of alleles) in population

  - increases chances of organisms inheriting harmful genetic defects

  - organisms vulnerable to new diseases (reduced gene pool)
• Inbreeding

  the mating of close relatives in species --> results in reduced gene pool
• Selective breeding in animals - desirable characteristics

  - maximum yield of milk, meat

  - good health

  - contains disease resistant alleles

  - attractive
• Selective breeding in animals process (natural selection vs artificial)

  NATURAL:

  - occurs naturally

  - results in development of population with features that are better adapted to their environment + survival

  - takes long time to occur (beneficial alleles pass down MANY GENERATIONS)

  
  

  ARTIFICIAL:

  - only occurs when humans intervene (breed the offspring by hand)

  - results in development of populations with features useful to humans (eg. angus cow meat)

  - takes less time as only individuals with desired characteristics are allowed to REPRODUCE
• RESTRICTION Enzymes + ligase enzymes

  Restriction enzyme used to cut the required GENE out of the DNA and the bacterial plasmid (DNA)

  (leaves DNA with sticky ends = short sections of single-stranded DNA that will pair with other sticky ends that contain complementary bases)

  ⬇️

  Ligase enzymes join the 2 pieces of DNA together if they have complementary sticky ends (form single, unbroken molecule of DNA)

  ⬇️

  2 bits of DNA stuck together are called RECOMBINANT DNA
• Vectors and recombinant DNA

  PLASMIDS + VIRUSES can act as VECTORS for genetic engineering

  (take pieces of DNA and insert this recombinant DNA into other cells)

  
  

  viruses - transfer DNA into human cells / bacteria

  
  

  plasmids - transfer DNA into bacteria / yeast
• vector

  something used to transfer DNA into a cell
• Recombinant DNA

  DNA of 2 different organisms combined as a result of gene transfer.

  THIS IS ALTERED DNA
• genetically engineered plasmids are inserted into bacterial cell

  bacteria reproduces - plasmids (DNA) are copied so recombinant plasmids can quickly be spread as the bacteria multiply --> express the gene and make human protein
• Human insulin

  - gene for human insulin inserted into bacteria (restriction enzyme cuts out gene from DNA + cuts out bacterial plasmid --> then ligase enzymes join the 2 pieces of a DNA together by their sticky ends to form recombinant DNA) which then produces human insulin which can be collected + purified for medical use for DIABETES
• How do the 2 pieces of DNA have matching sticky ends?

  Cut by the same restriction enzymes
• Why insert the recombinant DNA into bacterial cell? Why use bacteria?

  - bacteria can reproduce rapidly --> then placed in fermenter (controlled conditions)

  - contains same genetic codes as organisms we are taking genes from (read genes easily + produce same proteins)

  - no ethical concerns

  - presence of PLASMIDS in bacteria separate the main bacterial chromosome = easy to remove + manipulate to insert genes into them
• Genetically modified plants = improve food production

  crops can be genetically modified to increase food production (GM crops)

  
  

  Can make crops resistant to pests = improve crop yield:

  PROS

  - farmers don't need to spray harmful pesticides

  - increased crop yield

  CONS

  - increase costs of seeds - companies that make GM seeds charge more to cover costs of developing them

  - smaller, poorer farmers cannot compete

  
  

  Can be modified to be resistant to certain herbicides:

  (herbicides are chemicals that kill plants)

  PROS

  - farmers can spray crops to kill weeds without affecting crop itself = better crop yield

  CONS

  - increase dependency on certain chemicals

  - more expensive seeds

  - reduce biodiversity as few plant species when herbicides have been used

  
  

  Can be modified to produce additional vitamin:

  - prevent deficiency diseases in areas of the world
• How are GM crops bad in terms of genes being transferred to wild plants?

  Inserted genes (recombinant) can be transferred to wild plants by POLLINATION = reduce effectiveness of GM crop (herbicide will not work on other crops like weed)
• Transgenic

  The transfer of genetic material from one species to a different species
• Genetic engineering

  Refers to the manipulation of DNA sequences of an organism
• Yeast in bread making:

  ANAEROBIC

  • yeast is mixed with flour and water.
  • yeast produces enzymes that break down the starch in the flour which releases sugars that can be used for anaerobic respiration
  • carbon dioxide produced during respiration is trapped in small air pockets in dough causing it to rise
  • during baking, any ethanol produced by the yeast (waste product of respiration) is evaporated
  • no further respiration of yeast when baking as high temperatures kill it