9th grade - Diseases and immunity

Which one of the following is least important in preventing the contamination of food?

• Not smoking while preparing food.

• Washing the hands before preparing food.

• Not coughing or sneezing over food.

• Keeping food away from flies

Which one of the following is the most appropriate description of a contagious disease? A contagious disease is one which is spread by

• contaminated food.

• contaminated drinking water.

• contact with an infected person.

• droplets from an infected person.

What is the purpose of the gauze mask worn by surgeons during an operation?

• The masks worn by surgeons prevent infected droplets from reaching the patient.

• The masks worn by surgeons prevent infected droplets from reaching the surgeon.

• The masks worn by surgeons prevent looking bad in fron of cameras.

• The masks worn by surgeons is only for decoration.

What sources of water are most likely to contain pathogenic bacteria?

• Water most likely to contain pathogenic bacteria will be that which receives untreated or partially treated sewage.

• Water least likely to be contaminated will be that which comes from unpopulated areas or has filtered through rock layers into underground aquifers.

• Water most likely to contain pathogenic bacteria will be that which receives no chemical treatment to be purified.

• Water least likely to be contaminated will be that which comes from very populated areas or has filtered through rock layers into water dams.

Which one of the following is least likely to prevent contamination of food by houseflies?

• A well-fitting trash can.

• Swatting or killing flies.

• Covering food with cling-film.

• Efficient sewage disposal

Which body cells are attacked by the malarial parasite?

• Red blood cells.

• White blood cells.

• Platelets.

• Lymphocytes.

Anti-malarial drugs kill the parasites in the blood but they do not cure the disease. Why is this?

• Anti-malarial drugs do not kill the parasites in the liver.

• Anti-malarial drugs are not strong enough to fight the parasite.

• Anti-malarial drugs kill the parasite, but also red cells.

• Anti-malarial drugs kill all the parasites, but humans must wait to get better.

Why was the use of DDT (dichlorodiphenyltrichloroethane) insecticide not successful in eradicating malaria?

• The mosquitoes became resistant to the DDT (dichlorodiphenyltrichloroethane) insecticide.

• The mosquitoes can migrate as birds when the season is upon them.

• The DDT (dichlorodiphenyltrichloroethane) is not used to erradicate plagues such as mosquitoes.

• The mosquitoes overcome in population the amout DDT (dichlorodiphenyltrichloroethane) insecticide used.

Which one of the following is least likely to give rise to food poisoning?

• Cooking and eating a partially defrosted turkey.

• Eating a cooked chicken leg straight from the refrigerator.

• Preparing a fresh chicken for the oven and immediately making a lettuce and tomato salad.

• putting an uncooked chicken on the same plate as some cold ham.

Salmonella species are non-spore-forming, predominantly with really small cell diameters.They are chemotrophs, obtaining their energy from oxidation and reduction reactions using organic sources. Salmonella in humans may cause several symptoms if the food is not well-prepared. What is the usual method of killing Salmonella bacteria in food?

• Cutting and chopping the food into small pieces so bacteria can no longer survive to a knife.

• Cooking usually kills Salmonella bacteria in food.

• Adding salt to the food, so bacteria may die from dehydration (osmosis).

• Washing the food with soap in the external parts.