B6b: Harmful microorganisms

Question 1

How can the transmission of diseases be prevented? (4)

Answer 1

food poisoning (bacterial) by food; good hygiene, properly cooking food

cholera (bacterial) by water; good sanitation, clean water supplies

influenza (viral) by airborne droplets; sneeze into tissue, wash hands, disinfect contaminated surfaces

athlete’s foot (fungal) by contact; wash feet regularly, do not walk bare foot, disinfect contaminated surfaces

Question 2

Stages of an infectious disease (4)

Answer 2

microbes enter into body (e.g. nose/mouth)

rapid growth/reproduction using moisture/warmth/food in body, incubation period

production of many toxins; damages cells+tissues

toxins causes symptoms, such as fever and pain

Question 3

Why do natural disasters cause a rapid spread of diseases? (4)

Answer 3

damage to sewage systems and water supplies, contaminated drinking water, +cholera

damage to electrical supplies/fridges causing rapid food decay, +food poisoning

displacement of people, live crowded together in poor sanitation camps, +spread of disease by contact

crowded/disrupted health facilities by damaged transport links

Question 4

Describe the pioneering work of Pasteur (3)

Answer 4

proved decay was caused by microbes in air, microbes entering the body would cause disease (germ theory)

carried out experiments to prove his theory

said if we could stop microbes entering body, we could prevent illness

Question 5

Describe the pioneering work of Lister (3)

Answer 5

developed antiseptics to kill microbes

surgeon; sprayed instruments with carbolic acid, killing microbes, ­ reducing postoperative infections

safer antiseptics now used to kill bacteria on surfaces + skin, ­reducing spread of microbes and ­infections

Question 6

Describe the pioneering work of Fleming (2)

Answer 6

discovered penicillin mould produced chemical that would kill bacteria

it grew on one of his agar plates of bacteria, caused area where bacteria could not grow as they were killed by the penicillin

Question 7

What are antiseptics and antibiotics used in and how? (3)

Answer 7

the control of disease

antiseptics kill bacteria on surfaces + skin, ­spread of microbes

antibiotics are drugs that kill bacteria (not viruses)

Question 8

How are some strains of bacteria developing resistance to antibiotics? (1+4)

Answer 8

natural selection

random mutations in some bacteria making them resistant to antibiotic

antibiotic kills bacteria without mutation

bacteria with resistance survive + reproduce, passing resistance gene on

eventually, whole population becomes resistant

Question 9

Explain the importance of various procedures in the prevention of antibiotic resistance (2)

Answer 9

only prescribe antibiotics when necessary; not for viral conditions or minor illnesses; reduce chance of resistant bacteria becoming common

complete dose of antibiotics given so all microbes killed before resistance can fully develop