Which chemical cleans best? How dirty is your desk?

Step 1 bottom with agar lid bottom with agar lid Turn your Petri dish upside down

Step 2 On the bottom of your Petri dish write your initials and the date bottom

Step 3 Mark the bottom of your Petri dish into quarters bottom

Step 4 In each quarter write the object and which chemical was used bottom

Step 5 bottom with agar lid bottom with agar lid Flip over your Petri dish so the lid is back on top Dip one of your cotton buds in water and rub what you want to test

Step 6 Take the lid off your Petri dish Wiggle your cotton bud on the agar GENTLY Remember to put it in the right quarter

Step 7 Put the lid back on your Petri dish between each test Put the used cotton bud in disinfectant Clean the object using your chemical and a paper towel, then re-swab onto agar

Step 8 When you have tested both object twice (clean and dirty) seal your dish with sellotape

How much growth? Rate the level of growth 0, 1, 2 or 3 Nothing is growing A couple areas of growth Mostly covered in growth Completely covered in growth

What cleans best? ChemicalIndividual ResultsClass average Lemon Juice Liquid Soap Surface Cleaner Mouthwash Wipes NOTHING Rate the level of growth 0, 1, 2 or 3 Use the class average results to construct a bar graph.

How is disease spread?

Skin Stomach Nose and Throat Mouth Ear Reproductive Organs Eye Mucus traps pathogens and hair brushes them out Saliva contains digestive juices which break down pathogens. Acid destroys pathogens before they can reach the small intestine. Acidic conditions in the vagina help to kill pathogens. As a whole it acts as a barrier to pathogens If it is damaged a scab will form Produce tears which contain a digestive juice which digests pathogens. Produce wax to trap any pathogens

What happens if microbes get past the first line of defence?

Antibiotics What do antibiotics do?

Antibiotics Antibiotics only kill bacteria. (they don’t work on viruses!) They kill any bacteria; good and bad.

Antibiotic Resistance ehavior/antibioticresistance/

Viruses HIV Antibiotic Resistance Avian flu Swine flu Protozoa Microbes Immune system cartoon BACTERIA

response-[90hSVkaOG_w].cfm immunesystem/ h/boogers/