Download Chapter 7: Infection and Disease Name____________________

Chapter 7: Infection and Disease
Name____________________
Part 1: Complete the sentence by circling the correct term:
1. Exotoxin: Toxins (poisons) released from a (virus/microorganism) into the surrounding medium or tissue during
the growth phase of infection.
2. Endotoxin: are produced by (live/dead) gram-negative bacteria, notably Salmonella.
3. A cyst is a protective (whip/capsule) that allows survival of the protozoan when conditions are unfavorable. The
cyst enables a protozoan to survive because it (propels/protects) the organism from adverse conditions, allowing
the organism to survive outside a host and thus enabling it to reinfect another suitable host.
4. Kuru was spread by (contact/consumption) of the brain tissue of dead relatives.
5. Prions contain (some/no) nuclear material (DNA or RNA): they are self-replicating proteins capable of infection.
6. Prions are able to replicate by initiating a change in a (harmful/harmless) (normal) protein PrP so that it too
becomes infectious. The infectious form may originate through a point mutation.
7. Amoebic dysentery is most likely to be (controlled/transmitted) where there are a large number of infected
individuals using one water supply for all their water requirements (hygiene, drinking), or where effluent is
entering the drinking supply.
8. Fungal infections tend to be chronic because fungi grow (quickly/slowly) (host’s immune system has opportunity
to fight the infection as it grows, keeping it at a low level).
9. An endoparasite is a parasite that lives (inside/outside) an organism (or its cells), whereas an ectoparasite lives
(on/off) the body surface.
10. Many diseases carried by insect vectors are restricted to tropical regions because these regions have large
populations of insects (which can breed (rapidly/slowly) & throughout the year in areas with high temperatures).
11. Cysts of the giardia parasite are found in water contaminated with faecal material and often occurs in remote
areas where reliable toileting facilities are not available (the parasite also favours conditions where the water is
(cool/warm), as in forested streams).
12. The cyst enables a protozoan to survive because it protects the organism from adverse conditions, allowing the
organism to survive (inside/outside) a host and thus enabling it to reinfect another suitable host.
13. The (bacterium/virus) Vibrio cholerae: The symptoms of cholera include vomiting and acute, watery, painless
diarrhoea. If untreated, the copious diarrhoea can quickly lead to severe dehydration and a consequent collapse
of all body systems (particularly kidney and heart failure).
14. HIV mutates very (slowly/rapidly), changing its protein coat. Any vaccine is quickly rendered useless as the virus
has already changed. There are also many different strains of HIV, each requiring a different vaccine.
15. Endocytosis is the means by which foreign material is normally (expelled/engulfed) by cells, prior to being
destroyed. This response of the cell enables the virus to gain entry into the cell.
16. Viruses are entirely (dependent/independent) on using the host’s cellular machinery to reproduce. Features that
equip them for this role include a minimal structure which is essentially just genetic material enclosed in a
protein coat, attachment structures which aid entry into the host, envelopes around the protein coat which
enable immune evasion, & specific enzymes, such as reverse transcriptase, which enable integration into the
host's chromosome.
17. Glycoprotein spikes are important in host recognition and attachment of the virus to the (pathogen/host) cell
18. Viruses may disrupt the normal cell mediated immune response, causing disease through (stopping/weakening)
the immune system
19. Viruses can directly destroy or disrupt the activities of the cells they (invade/engulf).
20. The immune response to the virus may (stop/trigger) symptoms of infection or lead to a disease in itself.
21. (Bacteria/Viruses) may interact with the host’s chromosomes to trigger cell changes leading to cancer.
22. Some viruses (e.g. Influenzavirus) acquire mutations (e.g. to their surface proteins) so rapidly that vaccines are
(easy/difficult) to develop and are quickly ineffective against new strains.
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23. Virion structure: A (double stranded/single) type of nucleic acid (DNA or RNA, double or single stranded) and a
few enzymes (e.g. reverse transcriptase in HIV), enclosed in a protein coat or capsid. The capsid may be covered
by an envelope of lipid, protein, or carbohydrate.
24. In developed countries a (greater/smaller) proportion of deaths are due to heart disease and cancers, and a
relatively small proportion (2%) are associated with infectious disease. In developing countries, infectious
diseases account for a much greater proportion of deaths (21%).
25. Intracellular protozoan parasites that cause disease are highly specialised with complex life cycles involving one
or more hosts. Because they are intracellular (reside (outside/within) the cells), it is difficult to control or treat
them without also damaging the host (human) cells. In addition, many pass part of their life cycle as cysts, during
which they are relatively resistant to treatment.
Part 2: Multiple Choice questions:
1. A slippery outer covering in some bacteria that protects them from phagocytosis by host cells is
a. capsule
b. cell wall
c. flagellum
d. peptidoglycan
2. A bacterial cell wall does all of the following except
a. gives shape and rigidity to the cell
b. is the site of action for some antibiotics
c. is associated with some symptoms of disease
d. protects the cell from Phagocytosis
3. A Gram negative cell wall is __________ than a Gram positive one.
a. thicker
b. thinner
4. Because penicillin prevents peptidoglycan synthesis, it is more effective on _______________ cells.
A. Gram positive
b. Gram negative
5. The genetic information of bacteria is stored in _______, in one circular chromosome located in the cytoplasm.
a. DNA
b. protein
c. phospholipids
d. RNA
6. The fact that viruses are obligate intracellular parasites means that they require a ____________________ for
reproduction.
a. culture dish
b. host cell
c. phenol red broth
d. secondary virus
7. The cell wall type that is most vulnerable to the action of penicillin is
a. Gram negative
b. Gram positive
8. Phagocytosis of the bacteria that cause pneumonia is ____ likely if the bacteria are protected by a capsule.
a. less
b. more
9. If you use a visible light microscope to examine a live culture of a bacterium possessing flagella, you will be able to
see the flagella moving the bacteria.
a. true
b. false
10. The optimum temperature for an organism is the one at which
a. it grows with the shortest generation time
b. it has the longest time between cell divisions
c. it is near one extreme of its range of tolerated temperatures d. its enzymes begin to denature
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Part 3: Short answers:
Question 1:
The figure shows the transovarian
passage of R rickettsii in the tick vector.
Horizontal transmission (i.e., acquisition
of the bacteria by uninfected ticks
feeding on infected animals) occurs less
often and is not shown. Humans become
incidental hosts after being bitten by an
infected adult tick.
How could the life cycle of the tick be
controlled to prevent infection to the
human?
Question 2:
Clubroot is caused by the pathogen
Plasmodiophora brassicai. This agent is
regarded as a protist, which means it is
an organism with plant, animal, and
fungal characteristics. P. brassicai is an
obligate parasite.
What is meant by obligate parasite?
What feature of the zoospore allows
this pathogen to “seek out” potential
hosts?
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Part 4: Read over the 4 pages of this revision & highlight all key terms = how many did you highlight?
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