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• what tool could be used to record the abundance of different plant species in a habitat?

  a quadrat
• what tool could be used to record the abundance of different flying insect species in a habitiat?

  a sweep net
• what tool could be used to record the abundance of different small crawling animal species in a habitat?

  a pitfall trap
• describe the mark-release-recapture method

  1. use a trap to capture some animals
  2. mark the captured animals
  3. release the animals
  4. set up the trap again in a couple of days
  5. note the number of animals in the recapture and the number of those that are marked
• five negative impacts that humans have on the environment

  • hunting
  • deforestation
  • pollution
  • land use
  • pesticides
• five positive impacts that humans have on the environment

  • sustainable farming
  • captive breeding programmes
  • creating nature reserves
  • recycling
  • preserving habitats
• biodiversity


  the variety in all the species living in an ecosystem
• three benefits to maintaining biodiversity

  • ecotourism provides money for the local economy
  • it can prevent extinction
  • some animals or plants may have useful medicinal properties
• two challenges to maintaining biodiversity

  • it is sometimes difficult to gain political agreement on policies
  • maintaining biodiversity is expensive
• how can changes in water levels affect ecosystems?

  • animals may have to migrate to find water
  • melting ice caps may destroy the habitats of some animals (either animals living in icy regions or by sea level rise)
• how can atmospheric gases affect ecosystems?

  • some organisms cannot survive when certain gases are present
  • polluted water can cause illness to animals that drink it
• five factors that affect food security

  • the human population size
  • the number of pests and pathogens
  • global warming and climate change
  • wealthier parts of the population requiring a larger variety of food
  • the high cost of farming methods
• hydroponics


  growing plants in nutrient mediums other than soil
• biological control


  controlling pests by deliberately introducing natural predators of the pest
• how can gene technology help agriculture?

  beneficial genes for pest resistance or the ability to grow in harsher conditions could be introduced
• how can fertilisers and pesticides help agriculture?

  • pesticides kill pests that could harm the growth of the plant
  • fertilisers provide the plant with all the nutrients it needs so that it can grow more quickly
• describe how selective breeding is carried out

  1. animals with the desired traits are chosen
  2. these animals are bred together
  3. repeat the process until the offspring have the desired traits
• genetic engineering

  altering the genome of an organism
• how are new genes introduced into an organism?

  • the organism's genes are cut using restriction enzymes to create sticky ends
  • the dna from a bacterium is also cut to produce sticky ends
  • the gene is inserted into the bacteria along with an antibiotic resistance gene
  • antibiotics are used to remove the bacteria that do not have the new genes
• transgenic organism


  an organism that contains foreign dna
• two advantages of genetically modified crops

  • better crop yields
  • food will last longer and taste better
• two disadvantages of genetically modified crops

  • new genes can easily spread to other plants in the environment
  • we don't know what long term effects genetically modified crops cause on health
• what is the difference between communicable and non-communicable diseases?

  • communicable diseases are diseases that can be spread
  • non-communicable diseases cannot be spread
• health


  a state of complete physical, mental and social well-being (as defined by the World Health Organization WHO)
• pathogen


  a microorganism that causes disease
• why are people with HIV more likely to catch tuberculosis?

  people with HIV have a weaker immune system and so are more susceptible to infection with tuberculosis
• What can HPV lead to?

  HPV can lead to certain types of cervical cancer
• five ways diseases can be spread

  • droplet infection
  • eating contaminated food
  • drinking contaminated water
  • direct contact
  • entry through wounds
• three ways the spread of diseases can be reduced

  • visual identification of the disease
  • DNA identification of the disease
  • screening with antibodies associated with the disease
• describe one bacterial disease that affects humans

  • salmonella (food poisoning)
  • transmitted by ingesting infected foods
  • symptoms - fever, sickness and diarrhea
• describe one bacterial disease that affects plants

  • crown gall disease (agrobacterium tumefaciens)
  • transmitted through cuts in the stems of plants
  • symptoms - tumor type growths
• describe one viral disease that affects humans

  • human immunodeficiency virus (HIV)
  • transmitted through bodily fluids and is commonly spread through sexual activities
  • symptoms - a rash and a fever like symptoms
• describe one viral disease that affects plants

  • tobacco mosaic virus (TMV)
  • transmitted through direct contact
  • symptoms - spots and a yellow coloured mosaic pattern
• describe one fungal disease that affects humans

  • athlete's foot
  • transmitted through direct contact or contact with skin particles
  • symptoms - dry and cracking skin between toes
• describe one fungal disease that affects plants

  • erysiphe graminis (barley powdery mildew)
  • transmitted through vectors like acids in damp and cold environment
  • symptoms - powdery growth and yellowing on the opposite side of the leaf
• two physical plant defenses against disease

  • thick cell wall
  • waxy cuticle
• how do plants use chemical defences to prevent disease?

  plants contain anti-microbial chemicals that can slow the spread of or kill bacteria
• three ways plant diseases can be identified

  • analysng DNA to see whether the plant contains any pathogen DNA
  • antigen detection to find any foreign antigens present in the plant
  • observation of symptoms
• function of platelets

  platelets are small fragments of cells that are involved in blood clotting
• function of white blood cells

  white blood cells are involved in phagocytosis and some white blood cells produce antibodies