disease Flashcards by Cian Zolfagharinia

What is meant by the term pathogen?

disease-causing (organism) ;

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Plasmodium is described as a parasite.

Define the term parasite.

lives , in / on , host ;
gains nutrition / feeds , from (host) ;
at the expense of / harms (host) ;

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Explain why the human body’s primary defences do not prevent the entry of Plasmodiuminto the body.

mosquito / vector / Anopheles , feeds on blood ;
breaks skin / skin cannot act as barrier / mosquito pierces
skin / mosquito bites skin ;

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Suggest why malaria is much more common in tropical areas than in other parts of the world.

suitable / AW , climate / temperature , for , mosquito / vector
/ Anopheles ; ora
more mosquitoes live there / AW ; ora
idea of relatively poor so methods of prevention less
effective ;

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Suggest two reasons why governments in parts of the world other than tropical areas, are also becoming increasingly concerned about malaria.

climate change / global warming / AW , may result in
spread to other parts of the world / AW ;
idea of increased movement of (infected) people ;
idea that (non-malaria) countries fund anti-malaria
measures via international aid ;
resistance of , parasite to drugs / mosquito to
insecticides ;

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In patients with IDA, anaemia is caused by the destruction of erythrocytes (red blood cells) by phagocytosis.
Suggest why erythrocytes that contain Plasmodium are more likely to be destroyed by phagocytosis than healthy erythrocytes

(different) chemicals that attract phagocytes (released from

infected erythrocytes) ;

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Antibodies are important biological molecules. Describe how the structure of antibodies allows them to perform their function.

2 light chains and 2 heavy chains / 4 polypeptide
chains ;
variable region allows , binding / attachment , to
antigen ;
two variable regions allow binding of more than
one (of the same) antigen ;
variable region on different antibodies allows specificity
to different antigens ;
constant region allows , recognition by / attachment to /
binding to , (named) phagocytes ;
hinge (region) allows flexibility ;
disulfide , bonds / bridges , hold , polypeptides / light
and heavy chains , together ;

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Outline the mode of action of antibodies in defending the body against pathogens by describing the processes of neutralisation and agglutination.

neutralisation
cover / block , binding site / antigen / receptor site (on
pathogen) ;
bind to toxins ;
prevent , binding / entry , to (host) cell ;
agglutination
clump / bind together , (many) pathogens ;
(clump) too large to , enter (host) cell / cross
membranes ;
increase likelihood of being consumed by (named)
phagocyte / more can be consumed by phagocyte at
once ;

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State what is meant by the term health.

mental and physical well-being ;

absence of disease ;

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The term immunity is often used when describing how vaccines work.
In a piece of school homework a student wrote:“Bacteria can evolve quickly and many are now immune to antibiotics.”
Explain why the student’s use of the word ‘immune’ was incorrect.

immunity involves / bacteria do not have , lymphocytes /
white blood cells / antibodies / memory cells /
plasma cells / an immune system ;
(correct term is) resistant ;
bacteria are unicellular / only multicellular organisms
(can) have an immune response;

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Why are phagocytes described as a secondary defence against pathogens?

(involved) after , pathogen / AW , has entered the

body ;

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Why is the response involving phagocytes regarded as non-specific?

(phagocytes) able to, digest / break down / engulf /
target / deal with, a range of / many
different , pathogens ; ora

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Explain how phagocytes, such as those shown in Fig. 3.1, are able to pass from the blood into the tissue fluid.

lobed / narrow , nucleus ;
(cells) can change shape ;
can squeeze / move / fit / AW , between cells
/ through pores , in (walls of) capillaries ;
histamine makes , capillary walls /
endothelium , leaky ;

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Bacterial pathogens initially attach to receptors on the surface of phagocytes.
Describe the process by which a pathogen is destroyed after it has become attached to the surface of a phagocyte.
In your answer you should describe clearly the sequence of events that takes place.

(pathogen) engulfed / enveloped / surrounded
by cytoplasm (from phagocyte) ;
endocytosis / phagocytosis ;
(formation of) phagosome / phagocytic
vacuole / phagocytic vesicle ;
(phago) lysosomes ;
(lysosomes / phagosome) move towards /
fuse with (each other) ;
(named) enzyme(s) / lysins / hydrogen
peroxide / free radicals (in lysosomes) ;
(pathogen) digested / broken down /
hydrolysed ;
(to) amino acid / sugar / glucose / fatty acid /
glycerol ;
(break down products) absorbed / AW (into
cytoplasm)
or
unwanted products removed (by exocytosis) ;
cytoskeleton involved in (endocytosis /
movement of vesicles) ;

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Name the infective agent that causes TB.

Mycobacterium /M. tuberculosis / M. bovis ;

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Describe how the infective agent that causes TB is transmitted from one individual to another.

droplets (containing pathogen) ;
(released by) coughing / sneezing ;
inhaled by (uninfected) , individual / AW ;

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Suggest three reasons why the incidence of TB is higher in the low income group.

overcrowded / AW (living space) ;
poorly ventilated (living space) ;
poor diet / malnourished ;
poor health ;
homelessness ;
idea that more likely to consume , meat / milk,
from infected cattle ;
idea of vaccination / medical treatment , more
difficult to access ;

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Explain why the influenza virus is usually described as a pathogen rather than a parasite.

pathogen causes disease / not all parasites cause
disease ;
(influenza) virus causes a disease / influenza is a
disease ;
parasite gains , nutrition / energy , from host ;
or
(influenza virus) does not gain , nutrients / energy ,
from host ;
virus takes over / AW , (host cell) DNA
/ genetic material ;

Define the term immune response.

(response) to an antigen ;

involves , lymphocytes / production of antibodies ;

Outline two ways in which antibodies reduce the threat from pathogens.

Z antibodies bind to antigens (on pathogen) ;
otherwise, mark as follows:
N1 neutralisation ;
N2 antibodies , cover binding sites on pathogen / bind to
toxins ;
N3 prevent , binding / entry , to (host) cell ;
A1 agglutination ;
A2 clump / bind together , (many) pathogens ;
A3 (clump) too large to enter host cell / increase likelihood
of being consumed by (named) phagocyte;
the following could be credited
O1 opsonisation ;
O2 activation of complement ;
O3 increase likelihood of being consumed by (named)
phagocyte ;
L1 lysins ;
L2 destroy / AW , pathogens ;

In an attempt to reduce the consequences of further outbreaks of influenza, the government encourages immunisation of key groups of people, such as the elderly and children that have another risk factor. Suggest two other groups who should be immunised and explain why immunisation for them would be particularly important.

G1 patients with , HIV+ / AIDS / transplant /
chemotherapy ;
E1 weak immune system / cannot produce (many)
antibodies ;
G2 pregnant women ;
E2 foetus / embryo , has undeveloped immune system
or
antibodies can cross placenta ;
G3 health workers
or
people , living / working , close to outbreak ;
E3 likely to be at (increased) risk (of disease) ;
G4 those with (named) chronic diseases ;
E4 idea of inability to withstand further disease / already
being in poor health ;

Other than the direct effects on health or reducing the number of deaths, suggest a reason why spending a large amount of money on immunisation is considered worthwhile.

idea of days lost at work / effect on economy ;
idea of costing more to deal with the ill people (than the cost
of vaccination) ; ora
idea of response to public opinion ;
idea of health service unable to cope ;
idea of eliminating a disease ;

Give one reason why, despite being aware of the immunisation programme, some people choose not to be immunised.

idea of:
being too busy / can’t be bothered / feel it is unnecessary ;
lack of trust in government ;
media scare stories ;
concerned about side effects ;
cost implication to individuals ;
allergic to vaccine ;
altruistic reason / other people more deserving ;
fear of needles ;
religious / cultural / ethical , reasons ;

The malarial parasite is carried by an insect, the female Anopheles mosquito.
Describe how the mosquito transmits the malarial parasite to a human.

(mosquito), is vector ;
Plasmodium / parasite, present in (mosquito), saliva /
salivary gland ;
idea that infected mosquito, feeds on / bites, human ;
Plasmodium / parasite, passes (from saliva) to blood ;

Suggest why the resistance of MRSA to existing antibiotics is of major concern to humans.

MRSA / it, is harder to treat / may become untreatable ; potential for, disease outbreak / epidemic / pandemic / killing many people ; developing new / more powerful, antibiotics, is expensive / takes time ;

Describe the changes in antibody concentration that occur in the patient’s blood during the primary response.

no antibodies detected before 4 days / antibodies appear at 4 days ; increase then decrease / peak ; figures for peak with time and antibody concentration ; decrease less steep than increase / AW ; ora antibody concentration returns to zero at 27 days ;

The patient was subsequently infected with the same pathogen 30 days after the initial infection. Draw a line on the graph to show the likely concentration of antibodies in the patient’s blood from 30 days onwards.

the drawn line should show higher peak and steeper initial increase ; antibodies appear between days 30 and 34 and concentration at 60 days above peak for primary response ;

Complete the table below by stating the name and function of each of the region of an antibody

hinge (region) ; flexibility / binding of more than one antigen ; constant / Fc (region) ; attachment / binding , to phagocytes ; ``` variable / hypervariable / Fab (region) ; binding / attachment , to antigens ; ```

Each winter, the UK government recommends that vulnerable members of the public are vaccinated against the influenza (flu) virus. State two groups of people that the government would consider as being vulnerable.

``` the elderly / older people ; ‘at risk’ children / young people ; pregnant women ; those with compromised immune systems ; those with chronic diseases ; health workers ; poultry workers / pig farmers ; ```

Suggest why the influenza vaccine has to be changed each year.

different strains of the virus / virus mutates (each year) ; (new strains have) different antigens ; idea that antibody produced , needs to match new strain / antigen ; ora

state two differences between the primary and secondary immune responses.

secondary response , starts earlier / has shorter delay before response ; ora secondary response , more rapid / faster ; ora secondary response , higher / produces more antibodies ; ora

Describe the role of these memory cells when the influenza virus enters the body.

recognise , virus / antigen / pathogen ; produce a clone ; can , change to / form , plasma cells (on infection) ; make antibodies (against influenza , virus / antigen) ; responsible for secondary response / destroy virus before symptoms appear ; can , change to / form , named T-cell ;

State why a doctor would not prescribe antibiotics to treat influenza.

(antibiotics) are, not effective against viruses / effective | (only) against bacteria (and fungi / protozoa ) ;

Suggest how Tamiflu® could help to reduce the spread of influenza.

fewer , viruses / pathogens , produced ; fewer , viruses / pathogens , (in droplets) when , sneezing / coughing ; (as) viruses / pathogens , cannot leave cell ; (so) cannot , infect / spread to , other cells ; idea of treating , large / proximate , population ;

Suggest why researchers in Nepal concentrated their research on plants that had been used in traditional medicine.

(plants) already identified as likely to have , medicinal properties / few side effects / AW ; reduces , time / effort , in finding , plants / active chemicals ; (possibly) reduces cost ;

Identify the infective agent that causes AIDS.

human immunodeficiency virus / HIV ;

The government has introduced needle exchange programmes for drug users. Explain how this may help reduce the transmission of AIDS.

(infective agent), in blood / body fluids ; idea of: used needles are contaminated ; ora reduces chance of sharing needles ; ora

State three factors that increase the chance of infection with TB.

not vaccinated against TB ; weakened immune system ; (lifestyle) e.g. poor diet / lack of protein / malnourished / smoking / alcoholism ; homelessness ; poor ventilation (of housing) / AW ; overcrowding ; close contact with people from / visiting, area where TB is common ; close / prolonged, contact with individual(s) with TB ; consumption of milk or beef, from infected cattle / in developing countries

Describe how cytokine molecules can stimulate specific groups of B lymphocytes to divide.

cytokine / interleukin / receptor has, specific / unique, shape ; (cytokine / interleukin), binds / attaches / bonds to / fits into, receptor ; receptor on (cell surface) membrane (of B lymphocyte) ; (receptor and cytokine have) complementary shapes ; activates / stimulates, clonal expansion / mitosis ;

State two features of the body that form part of the primary defence. For each feature explain how it helps to prevent the entry of pathogens and parasites into the body.

skin ; idea of: physical barrier to prevent entry of microorganisms ; mucous membrane(s) / goblet cells ; (produce) mucus to trap, pathogens / parasite ; OR mucus ; traps pathogens ; cilia / ciliated epithelium ; remove, pathogen / parasite, laden / AW, mucus ; blood clotting ; prevents, pathogens / parasite, entering bloodstream ; ear wax / nasal hairs ; traps, pathogens / parasite ; lysozyme / tears / nasal secretions / saliva ; kills bacteria / contains antibacterial agent ; gastric juice / stomach acid ; kills, pathogens / parasite ;

Define the term parasiteand suggest how the threadworm benefits from this relationship.

lives, on / in / in contact with, and harms host ; takes nutrition from / feeds on (host) ; warmth ; protection / safe place / AW ; allows transmission / spread, to a new host / AW ;

suggest two ways in which the cycle of infection could be broken.

wash / clean / disinfect / sterilize, hands ; not, scratching / touching, of anus ; drugs to, kill / remove, parasite / eggs ;

Suggest two further benefits of using antibiotics.

reduces / prevents (infectious) disease ; prevent, problems / named problem, with gut ; digest food more, efficiently / easily / quickly ; greater proportion of, food / energy, can contribute to growth ; reduce risk of transmitting, pathogens / named pathogen, to humans

The use of antibiotics as growth promoters in animal production was banned in the European Union in 2006.Suggest a concern that led to this ban.

(antibiotic) resistant, pathogens / bacteria ; antibiotics kill useful, bacteria ; idea of: antibiotic passing into human food ;