Microbiology worksheet with answers

Vaccines protect against disease mainly by:

1. AStimulating the immune system to form memory cells
2. BProviding ready-made antibodies that remain in the blood for life
3. CBlocking all viruses from entering cells
4. DKilling bacteria directly in the blood

Which is part of the body's first line of defence against infection?

1. AIntact skin
2. BCytotoxic T cells
3. CAntibodies
4. DMemory B cells

Why are viruses called obligate intracellular parasites?

1. AThey can only replicate inside a living host cell
2. BThey can only be seen inside a cell under a microscope
3. CThey always kill the host cell immediately
4. DThey only live inside the intestine

Cholera causes profuse "rice-water" diarrhoea. What is the most important treatment?

1. AAntifungal drugs
2. BReplacing fluid and salts by oral or intravenous rehydration
3. CAntiviral drugs
4. DStopping all oral fluid intake so that the bowel can rest and recover

In the lysogenic cycle of a bacteriophage, what happens to the phage DNA?

1. AIt leaves the cell through the pilus
2. BIt is integrated into the bacterial chromosome as a prophage
3. CIt is immediately used to make new phages that burst the cell
4. DIt is destroyed by the bacterium

Which type of immunity is given by breast milk antibodies?

1. AArtificial active immunity
2. BNatural passive immunity
3. CNatural active immunity
4. DArtificial passive immunity

Corynebacterium diphtheriae causes diphtheria only if it produces diphtheria toxin. When does it make this toxin?

1. AOnly after it has conjugated with E. coli and received a plasmid
2. BWhen it carries a bacteriophage with the toxin gene
3. COnly when it is grown at high temperature
4. DWhenever it is exposed to antibiotics

Why are penicillins ineffective against Mycoplasma pneumoniae?

1. AIt lives only inside red blood cells
2. BIt has a thick waxy mycolic acid layer that blocks entry
3. CIt has no cell wall for penicillin to act on
4. DIt produces large amounts of beta-lactamase