B6

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

  quadrat
• what tool could be used to measure the abundance of different flying insect species in a habitat

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

  a pitfall trap
• describe capture-recapture 


  1. use a trap to capture some animals

  2. mark the captured animals and release them

  3. set up the trap again in a couple of days

  4. note the number of animals in the recapture and the number of those who are marked
• 5 negative impacts humans have on the environment

  - hunting

  - deforestation

  - pollution

  - land use

  - pesticides
• 5 postive impacts humans have on the environment

  - sustainable farming

  - captive breeding programmes

  - creating nature reserves

  - recycling

  - preserving habitats
• define biodiversity 


  the variety in all living species in an ecosystem
• 3 benefits of maintaining biodiversity

  - ecotourism provides money for the local economy

  - prevent extinction

  - some animals or plants can have useful medicinal properties
• 2 challenges of maintaining biodiversity

  - it can be expensive

  - it can be difficult to gain political agreements on policies
• how can changes in water levels affect ecosystems 


  - animals might have to migrate to find water

  - melting ice caps may destroy the habitats of animals
• 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
• 5 factors that affect food security

  - human population size

  - number of pests and pathogens

  - global warming and climate change

  - high cost of farming methods

  - wealthier parts of the population requiring more variety of foods
• what is hydroponics 


  growing plants in nutrients mediums other then soil
• what is 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 can harm the growth of the plant

  - fertilisers provide the plants with all the nutrients it needs to 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 has the desired trait
• what is genetic engineering

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

  - the organisms 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 insterted into the bacteria along with an antibiotic resistence gene

  - antibiotics are used to remove the bacteria that doesn't have the new genes
• what is a transgenic organism 


  an organism that contains foreign DNA
• give 2 advantages of genetically modified crops

  - better crop yields

  - food will last longer and taste better
• give 2 disadvantages of genetically modified crops

  - the new genes can easily be spread to other plants in the environment

  - we don't know the long term effects of GM crops on health
• what is the difference between communicable and non-communicable diseases

  communicable diseases can be spread whereas non-communicable diseases cannot be spread
• define health 


  a state of complete mental, physical and social well-being - not just the absence of disease
• what is a pathogen 


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

  people with HIV have a weakened immune system which means they are more suseptable to infections such as tuberculosis
• what can HPV lead to

  certain types of cervical cancer
• give 5 ways diseases can be spread

  - droplet infection

  - eating contaminated food

  - drinking contaminated water

  - direct contact

  - entry through wounds
• 3 ways the spread of diseases can be reduced

  - visual identification of diseases

  - DNA identification of diseases

  - screening for antibodies associated with the disease
• describe one bacterial disease that affects humans

  - salmonella

  - transmitted by ingesting contaminated food

  - symptoms: fever, sickness and diarrheoa
• describe one bacterial disease that affects plants

  - crown gall disease

  - transmitted through cuts in the stems of plants

  - symptoms: tumor type growth
• describe one viral disease that affects humans

  - HIV

  - transmitted through bodily fluids and commonly spread through sexual activity

  - symptoms: rash and fever
• describe one viral disease that affects plants

  - tobbaco mosaic virus - TMV

  - transmitted through direct contact

  - symptoms: spots and yellow coloured pattern
• describe one fungal disease that affects humans

  - athletes foot

  - transmitted via direct contact

  - symptoms: dry crackling skin
• describe one fungal disease that affects plants

  - barley powdery mildew

  - transmitted through vectors such as aphids in cold and damp environments

  - symptoms: powdery growth and yellowing on the other side of the leaf
• 2 physical plant defences against disease

  - thick cell wall

  - waxy cuticle
• how do plants use chemical defenses to prevent diseases

  plants contain antimicrobial chemicals that slow down the spread or kill the bacteria
• 3 ways plant diseases can be identified

  - analysing DNA to see if it contains pathogen DNA

  - observation of symptoms

  - antigen detection to find foreign antigens present in the plant
• what is the function of platelets

  blood clotting
• what is the function of white blood cells

  involved in phagocytosis and some produce antibodies that combat the pathogen