paper 4

• release of undigested food: egestion
• preclinical trials: when drugs are tested on human cells
• fungal infections [barley powdery mildew] are spread through spores being carried in the wind and enter the plant throush the stomata.
• a placebo is used because it serves as a control treatment, and it can act as a comparison to the real drug, it removes any psychological effect.
• a community has the most organisms in any ecosystem
• sampling techniques

  abundance: quadrats

  distribution: transect
• treating cardiovascular disease

  reduce blood pressure:

  • beta blockers - block the effects of adrenaline
  • nitrates - widen blood vessels
• decomposition

  decomposition is caused by microorganisms such as bacteria and fungi. the microorganisms use the process of respiration to release the energy in dead organisms. decomposition also allows minerals to be recycled in nature for plants to use.
• two ways the body's immune system destroys invading cells

  1. Lymphocytes produce antibodies that attack the antigens on pathogens.
  2. Phagocytes engulf pathogens.
• meiosis produces gametes
• explain why the students put different volumes of clean pond water into each beaker

  • keeps the volume constant
  • allows them to observe the effects
• adding sodium bicarbonate keeps the carbon dioxide levels the same in each beaker/experiment
• genomic medicine: designing drugs that are specific to a particular variant of a gene
• adaptation of white blood cells

  they can change their shape to squeeze out of capillaries
• role of an antibiotic resistance marker in genetic engineering

  to identify which bacteria has taken up the plasmid
• antibodies are specific to ONE antigen
• how are antibodies made? [2]

  they are produced by lymphocytes when foreign antigens are detected
• what is an antibody? [2]

  a protein produced by lymphoctyes that clumps pathogens together so phagocytes can engulf them
• two uses of monoclonal antibodies

  • pregnancy tests
  • detecting diseases/cancer
  • treating diseases/cancer
• why are tumour cells used in making monoclonal antibodies? [1]

  they divide rapidly and can produce many cells
• parasite: an organism that lives on or in another living organism causing it harm
• why do gardeners add compost to their soil?

  the compost provides minerals for the plants
• mRNA carries the code for proteins