Use of biological resources

• Glasshouses

  • Conditions that can be manipulated to increase the rate of photosynthesis:
  • Artificial heating
  • Artificial lighting
  • Increasing carbon dioxide content
  • Regular watering
• Polythene tunnels

  Large plastic tunnels that cover crops
• Polythene tunnels

  • Protect crops from weather effects
  • Increase temperature slightly inside
• Factors that limit the rate of photosynthesis

  • Temperature
  • Light intensity
  • Carbon dioxide concentration
• Temperature


  As temperature increases, the rate of photosynthesis increases up to a certain point, then decreases as enzymes begin to denature
• Light intensity

  The more light a plant receives, the faster the rate of photosynthesis, until another factor becomes limiting
• Carbon dioxide concentration

  The more carbon dioxide present, the faster the rate of photosynthesis, until another factor becomes limiting
• Fertilisers

  Increase the amount of key nutrients in the soil for crop plants, allowing them to grow larger and healthier, increasing yields
• Key nutrients provided by fertilisers

  • Nitrogen
  • Phosphorus
  • Potassium
• Nitrogen

  Absorbed as nitrates, needed to make amino acids and proteins, lack causes weak growth and yellowing
• Phosphorus

  Absorbed as phosphates, needed for DNA and cell membranes, lack causes poor root growth and discoloured leaves
• Potassium

  Allows enzyme reactions for ATP production and photosynthesis, lack causes poor growth of flowers and fruits, and brown spots on leaves
• Types of pesticides

  • Insecticides
  • Herbicides
  • Fungicides
• Advantages of pesticides

  • Easily accessible
  • Cheap
  • Have an immediate effect
  • Kill the entire pest population
• Disadvantages of pesticides

  • Pests can develop resistance
  • Need to be repeatedly reapplied
  • Can kill other beneficial organisms
  • Organisms that eat pests can be infected
• Biological control


  Introducing a species to prey on the pest
• Advantages of biological control

  • No pollution
  • No resistance
  • Can target specific species
  • Long lasting
  • No need for reapplication
• Disadvantages of biological control

  • May eat other organisms
  • Takes long time to be effective
  • Cannot kill entire population
  • May not adapt to new environment
  • May become a pest itself
• Making bread

  1. Yeast carries out anaerobic respiration, producing alcohol and carbon dioxide

  2. Yeast enzymes break down starch to sugars

  3. Carbon dioxide trapped in dough causes it to rise

  4. Dough baked, alcohol evaporates, yeast killed
• Investigating anaerobic respiration in yeast

  1. Mix yeast and sugar solution

  2. Add oil to prevent oxygen entry

  3. Connect to limewater tube

  4. Measure carbon dioxide production rate at different temperatures
• Using bacteria to make yoghurt

  1. Sterilise equipment

  2. Pasteurise milk to kill unwanted bacteria

  3. Add Lactobacillus bacteria

  4. Incubate at 40-45°C, Lactobacillus ferments lactose to lactic acid

  5. Stir and cool to 5°C to halt Lactobacillus
• Fermenters

  Containers used to grow microorganisms like bacteria and fungi in large amounts
• Conditions in fermenters

  • Aseptic precautions
  • Nutrients
  • Optimum temperature
  • Optimum pH
  • Oxygenation
  • Agitation
• Fish farms

  • Ability to selectively breed for quality and growth
  • Ability to protect from predators
  • Ability to control water quality
  • Ability to control feeding
• Methods used in fish farms to ensure high yield

  • Maintenance of water quality
  • Control of intraspecific predation
  • Control of interspecific predation
  • Control of disease
  • Removal of waste products
  • Quality and frequency of feeding
  • Use of selective breeding
• Characteristics that plants are selectively bred for

  • Disease resistance
  • Increased crop yield
  • Hardiness to weather
  • Better tasting fruits
  • Large or unusual flowers
• Fish farming

  • Keeping fish in small numbers to minimise the spread of diseases
  • Removing waste products by filtering water to remove faeces and sewage
  • Cleaning fences, nets and tanks or changing location of fish to ensure clean water
  • Feeding fish food high in nutrients to ensure fast growth
  • Feeding fish frequently but in small amounts to avoid overeating or eating each other
• Selective breeding of fish

  1. Separating fish by gender

  2. Allowing only fish with desired characteristics to reproduce

  3. Passing on fast growing genes more frequently
• Selective breeding of plants


  • Developing disease resistance in food crops
  • Increasing crop yield
  • Improving hardiness to weather conditions
  • Improving taste of fruits
  • Developing large or unusual flowers
• Selective breeding of animals

  1. Breeding individuals with desired characteristics

  2. Selecting offspring with desired characteristics

  3. Repeating process for many generations
• Characteristics animals are selectively 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
• Problems with selective breeding

  • Inbreeding leading to reduced gene pool
  • Increased chance of inheriting harmful genetic defects
  • Increased vulnerability to new diseases
• Natural selection vs Selective breeding

  • Natural selection occurs naturally
  • Selective breeding is faster
  • Natural selection develops features better adapted for survival
• Genetic engineering using restriction enzymes

  1. Cutting required gene out of DNA

  2. Cutting DNA with restriction enzymes to create 'sticky ends'

  3. Cutting bacterial plasmid with same restriction enzyme

  4. Joining plasmid and isolated gene using DNA ligase
• Plasmids

  Vectors for genetic engineering that can take up pieces of DNA and insert recombinant DNA into other cells
• Viruses

  Vectors for genetic engineering that can transfer DNA into human cells or bacteria
• Genetic engineering using plasmids

  1. Genetically engineered plasmid is inserted into a bacterial cell

  2. Bacteria reproduce and plasmids are copied

  3. Recombinant plasmid is spread as bacteria multiply

  4. Bacteria express the gene and make the human protein
• Genetic engineering using bacteria

  1. Genetically engineered bacteria are placed in a fermenter

  2. Bacteria reproduce quickly in controlled conditions

  3. Bacteria make large quantities of the human protein
• Genetically modified plants

  Plants that have had foreign DNA inserted into their genome
• Reasons for genetically modifying plants

  • Improve food production
  • Increase resistance to insect pests
  • Increase resistance to herbicides
  • Improve nutritional value
  • Increase drought resistance