infection + response

Question 1

define what a drug is

Answer 1

a substance that changes the way your body works

Question 2

what are the 3 stages of drug trials (full explanation)

Answer 2

STAGE 1 - DRUG DISCOVERY

you test using:
- predictions based on public reaction
- computer models
- cultured cells
- pure proteins

STAGE 2 - ANIMAL TESTING

mostly:
- mice
- rats
- guinea pigs

eventually:
- pigs
- dogs
- monkeys

STAGE 3 - TESTING ON HEALTHY VOLUNTEERS

phase 1 - low dose of safety test on a few patients

phase 2 - more patients checking for efficacy with higher doses (most drugs fail here)

phase 3 - more patients, confirming efficacy, detecting rarer side effects

phase 4 - (after drug is accepted) set to the public but checking for drug effectiveness and identifying adverse reactions

Question 3

define blind trials

Answer 3

patients don’t know if they’ve been given the drug or not

Question 4

define double blind trials

Answer 4

both patient AND doctor don’t know who has been given the drug

Question 5

define placebo

Answer 5

a substance that doesn’t contain any drug

Question 6

define antibody

Answer 6

• Y-shaped protein
• produced by lymphocytes –> these are specific to a pathogen’s antigens

Question 7

define antigen

Answer 7

• the surface or components of a cell or structures
• surface membrane of pathogen

Question 8

explain fully the 4 stages to producing monoclonal antibodies

Answer 8

1) inject the mouse with antigens

2) the mouse produces lymphocytes to produce antibodies

3) remove the lymphocytes from the mouse’s spleen - these can make antibodies but cannot divide

4) fuse the lymphocytes with cancer cells - these cannot make antibodies however they do divide

this creates a HYBRIDOMA which can divide infinitely and make antibodies

Question 9

what is a pure monoclonal antibody

Answer 9

these will attach itself to only one antigen on one kind of bacterium or virus.
antibodies are then used to diagnose infectious diseases with unprecedented speed & certainty

Question 10

what are ‘humanized monoclonal antibodies’

Answer 10

MABs are ‘humanized’ by replacing much of the antibody that triggers the immune response with the corresponding human antibody structure

Question 11

what are transgenic mice

Answer 11

to eliminate huminisation, transgenic mice are used.
a human gene is placed in the mice so that they produce human antibodies
–> raises problems about ethics of genetic engineering

Question 12

uses of monoclonal antibodies in pregnancy tests (6)

Answer 12

1 - hCG hormone is detected in a woman’s urine during a pregnancy test

2- antibodies for hCG are bound to a coloured bead (blue)

3 - when urine is applied to the specified area, any hCG will bind to the antibody on the beads
–> antigen - antibody complex

4 - urine then moves up the stick to the test strip, carrying any beads with it

5 - the test strip contains antibodies to hCG that are stuck in place

6 - the strip turns blue if hCG is present because the immobilised antibody binds to any hCG
if no hCG is present, the bead will pass the test area without binding to anything; no blue

Question 13

what 4 things do plants need

Answer 13

• nitrogen (from nitrate)
• phosphorus (gets from phosphorus)
• potassium (gets from potassium ions)
• magnesium - (gets from magnesium ions)

these are found in salts dissolved in water

Question 14

what are the purposes of the 4 nutrients of a leaf

Answer 14

• nitrogen -> used for making leaves (photosynthesis)
• phosphorus -> used for making rocks
• potassium -> used for making flowers & fruit
• magnesium -> used for making chlorophyll

Question 15

effects on a plant when there is no nitrogen (mineral deficiency)

Answer 15

• stunted growth
• upper leaves pale green
• lower leaves yellow & dead
• weak stem

Question 16

effects on a plant when there is no phosphorus (mineral deficiency)

Answer 16

• purple leaves
• small roots

Question 17

effects on a plant when there is no potassium - (mineral deficiency)

Answer 17

• poor flower/fruit growth
• yellow leaves with dead spots

Question 18

effects on a plant when there is no magnesium (mineral deficiency)

Answer 18

• upper leaves normal
• lower leaves pale green or yellow

Question 19

plant pest and disease symptoms (and identifying)

Answer 19

• stunted growth
• spots on leaves
• area of decay (rot)
• growths
• malformed stems or leaves
• discolouration
• presence of pests

you can identify by:
–> referencing gardening manual/website
–> take infected plants to a lab to identify pathogens
–> using testing kits that contain monoclonal antibodies

Question 20

explain fully:
Ashdieback
Xylella fastidiosa

Answer 20

• it is caused by fungus; transmitted via spores in the wind
• it affects Ash trees by damaging leaves and then spreading through the plant
• it is usually fatal
• imports of ash from Europe is now banned
• UK population of ash is estimated to be 80 million trees

Question 21

physical defences of plants

Answer 21

• waxy cuticle on leaves (stomata still lets them in)
• bark on trees
• cellulose cell walls
• layers of dead cells which fall off taking pathogens with them

Question 22

chemical defences of plants

Answer 22

• produces antibacterial chemicals, such as mint and witch hazel
• produces poisons to deter herbivores, such as tobacco, foxgloves and deadly night-shade

Question 23

mechanical defences of plants

Answer 23

• thorns and hairs deter animals from touching/eating them
• leaves which droop/curl when touched
• mimicry to trick animals into eating or laying eggs on them