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infection and response Flashcards

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1
Q

What are pathogens?

A
  • microorganisms that cause infectious disease
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2
Q

What are the type of pathogens?

A
  • viruses
  • bacteria
  • protists
  • fungi
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3
Q

How can pathogens be spread?

A
  • direct contact
  • by water
  • by air
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4
Q

How are pathogens spread through direct contact?

A
  • touching contaminated surfaces
    e.g. kissing, contact with bodily fluids, direct skin to skin, microorganisms
    from faeces, infected plant material left in field
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5
Q

How are pathogens spread in water?

A
  • drinking or coming into contact with dirty water
    e.g. cholera
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6
Q

How are pathogens spread in the air?

A
  • pathogens can be carried in the air and then breathed in
  • droplet infection - sneezing, coughing or talking expels pathogens in droplets which can be breathed in
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7
Q

How do viruses cause cell damage?

A
  • move into the cells and use the biochemistry of it to make copies of itself
  • leads to cell bursting and releasing copies into the bloodstream
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8
Q

How do viruses make us feel ill?

A
  • damage and destruction of cells when it bursts make individual feel ill
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9
Q

How does bacteria make us feel ill?

A
  • they produce toxins that can damage cells
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10
Q

What are protists?

A
  • eukaryotic pathogens which are sometimes parasitic - use humans and animals as their hosts
  • often transferred between organisms by vectors
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11
Q

What are fungi?

A
  • can be single-celled or have a body made up of hyphae
  • grow and penetrate human skin and the surface of plants, causing diseases
  • hyphae can produce spores that can be spread to organisms
  • spores can travel through the wind and infect organisms
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12
Q

What are vectors?

A
  • animals that carry a disease but do not get the disease themselves
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13
Q

How do bacteria and viruses spread?

A
  • they reproduce rapidly inside the body - binary fission
  • they divide every 20 minutes under ideal conditions
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14
Q

What is the difference between bacteria and viruses?

A
  • viruses themselves cannot reproduce - only once they enter a host cell
  • bacteria can reproduce by themselves
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15
Q

How can we reduce the spread of pathogens?

A
  • Improving hygiene - hand washing, using disinfectants, isolating raw meat, using
    tissues and handkerchiefs when sneezing
  • Reducing contact with infected individuals
  • Removing vectors - using pesticides or insecticides and removing their habitat
  • vaccination- by injecting a small amount of a harmless pathogen into an individual’s
    body, become immune, will not infect them, cannot pass it on.
  • Use condoms to prevent transmission of STIs
  • Provide clean drinking water rather than containing cholera
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16
Q

What is a communicable disease?

A
  • a disease that can be spread from person to person
  • are infectious and are spread via pathogens
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17
Q

What pathogen causes measles?

A
  • virus
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18
Q

What are the symptoms of measles?

A
  • fever and red skin rash
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19
Q

How can measles be fatal?

A
  • can lead to other problems such as pneumonia (lung infection), encephalitis (brain infection), and blindness
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20
Q

How are measles spread?

A
  • droplets in the air
  • when an infected person coughs or sneezes are inhaled by another person
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21
Q

How can measles be prevented?

A
  • vaccinations for young children to reduce transmission
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22
Q

What pathogen causes HIV?

A
  • virus
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23
Q

What are the symptoms of HIV?

A
  • initially flu-like symptoms
  • disappears after one or two weeks
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24
Q

What happens if HIV isn’t successfully controlled?

A
  • virus attacks the patient’s immune cells
  • over time, immune system becomes severely damaged
  • immune system becomes so badly damaged, that it is unable to fight off other infections
  • patients can now easily contract infections like tuberculosis and cancer
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25
Q

How is HIV spread?

A
  • through sexual contact or exchange of bodily fluids
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26
Q

What is late-stage HIV called?

A
  • AIDS - a state in which the body is susceptible to many different diseases
  • at this point, the disease is fatal
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27
Q

How can HIV be prevented/treated?

A
  • using condoms, not sharing needles, screening blood when used in transfusions
  • use of antiretroviral drugs (stops the virus from replicating)
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28
Q

How do antiretroviral drugs work in HIV?

A
  • prevent the virus from multiplying inside the patient
  • virus does not damage the patient’s immune system any further
  • patients who take these drugs do not go on to develop AIDS, can lead a normal life expectancy
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29
Q

Why aren’t antiretroviral drugs a cure for HIV/AIDS?

A
  • must be taken for the rest of the patient’s life
  • otherwise the viruses will start reproducing again and damage the immune system
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30
Q

What pathogen causes TMV?

A
  • virus
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31
Q

What is TMV?

A
  • a widespread plant pathogen affecting many species of plants including tomatoes
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32
Q

What are the symptom of TMV?

A
  • discolouration of the leaves -gives a distinctive ‘mosaic’ pattern
  • stunted growth
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33
Q

Why is TMV bad for a plant?

A
  • discolouration means less chlorophyll - rate of photosynthesis reduces
  • negative effect on the growth of the plant - less glucose is produced, therefore less amino acids and proteins can be produced
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34
Q

How is TMV spread?

A
  • contact between diseased and healthy plants
  • insects act as vectors
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35
Q

How can TMV be prevented?

A
  • good field hygiene and pest control
  • growing TMV-resistant strains
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36
Q

What pathogen causes salmonella?

A
  • bacteria
  • they live in the gut of different animals
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37
Q

What are the symptoms are salmonella?

A
  • fever, stomach cramps, vomiting, diarrhoea
  • caused by the toxins they secrete
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38
Q

How is salmonella spread?

A
  • spread by bacteria ingested in food
  • by food prepared in unhygienic conditions
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39
Q

How can salmonella be prevented?

A
  • poultry are vaccinated against salmonella
  • keeping raw meat away from cooked food
  • wash hands and surfaces when handling
  • cook food thoroughly
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40
Q

What pathogen causes gonorrhoea?

A
  • bacteria
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41
Q

What are the symptoms of gonorrhoea?

A
  • thick yellow or green discharge from the vagina or penis
  • pain when urinating
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42
Q

How is gonorrhoea spread?

A
  • via unprotected sexual contact
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43
Q

How is can gonorrhoea be prevented/treated?

A
  • using contracpetion
  • antibiotics - used to be easily treated with penicillin but bacteria developing antibiotic-resistant strains
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44
Q

What pathogen causes rose black spot?

A
  • fungi
45
Q

What are the symptoms of rose black spot?

A
  • purple or black spots develop on the leaves of a plant
  • often turn yellow and drop early
46
Q

Why is rose black spot bad for a plant?

A
  • rate of photosynthesis is reduced due to a lack of chlorophyll in the yellow areas of the leaves
  • reduces the rate of growth of the plant , less glucose, less amino acids and proteins, less growth
47
Q

How is rose black spot spread?

A
  • spores of the fungus are spread in water or by wind
48
Q

How can rose black spot be prevented/treated?

A
  • using fungicides
  • removing and destroying the affected leaves to prevent the fungus spreading to the other parts of the plant
  • have to be burnt
49
Q

What pathogen causes malaria?

A
  • protists
  • enters the RBC and damages them
50
Q

What are the symptoms of malaria?

A
  • repeating episodes of fevers, shaking (when protists burst out of the cell)
51
Q

How is malaria spread?

A
  • vector is the female mosquito - protists reproduce sexually
  • when mosquito punctures skin, protists enter the human bloodstream via their saliva
  • infected person bitten by another mosquito
  • blood of the person containing malarial pathogen passes into the mosquito
  • infected mosquito bites a different person and passes the malaria protist to them
52
Q

How can malaria be prevented?

A
  • preventing vectors from breeding - draining areas of still water
  • spraying insecticides - kills the mosquitos
  • mosquito nets - avoid being bitten (these nets may be covered in insecticides)
  • antimalarial drugs - kills parasites that enter the blood
53
Q

What are the non-specific human defence systems?

A
  • prevents pathogens from entering the body
  • skin, nose, trachea and bronchi, stomach
54
Q

How does the skin protect the human body against pathogens?

A
  • acts as a protective physical barrier -has a layer of dead cells, difficult for pathogens to penetrate
  • secretes antibacterial substances - kill pathogens on its surface
  • skin flora (good microorganisms) compete with bad for space and nutrients
  • forms scabs when it is damaged
55
Q

How does the nose protect the human body against pathogens?

A
  • lined with nose hair and mucus - traps and prevents pathogens from entering the respiratory system
56
Q

How do the trachea and bronchi protect the human body against pathogens?

A
  • lined with cilia (hair-like structures) - wafts pathogen-containing mucus upwards where it can be swallowed and killed by stomach acid
  • lined with mucus - traps pathogens
57
Q

How does the stomach protect the human body against pathogens?

A
  • contains hydrochloric acid - kills pathogens and microorganisms found in food
  • prevents them from entering the blood via the digestive system
58
Q

What happens if a pathogen enters the body?

A
  • the immune system tries to destroy it and any toxins they produce
  • protects us in case the same type of pathogen invades us in the future
59
Q

What happens if the non-specific defence systems are unable to prevent and kill the pathogen and it gets into the blood?

A
  • we rely on white blood cells to defend our body from infection
60
Q

What are the 3 ways can white blood cells defend our bodies against pathogens?

A
  • phagocytosis
  • antibody production
  • antitoxin production
61
Q

How does phagocytosis defends our body against pathogens?

A
  • WBC called phagocytes detect the foreign antigen and engulf, ingest and destroy pathogens using enzymes
62
Q

How does antibody production defends our body against pathogens?

A
  • each pathogen has an antigen on their surface which a specific complementary antibody can bind to
  • once antibodies bind, pathogens start to clump together - easier for WBC to find and destroy them
  • if you become infected again with the same pathogen, the complementary antibody will produce at a faster rate - symptoms not felt
63
Q

How does antitoxin production defends our body against pathogens?

A
  • neutralise the toxins produced by bacteria
  • binds to the toxins and prevents them from damaging cells to prevent us feeling ill
64
Q

How do vaccinations work?

A
  • contain small quantities of a dead or inactive form of a pathogen- dead so it will not infect the patient
  • foreign antigen stimulates the WBC to produce antibodies against the dead or inactive pathogen – antibodies will be specific in shape to the antigen binding site of the pathogen
  • lymphocytes become memory cells and divide by mitosis and remain in the body for years
  • when re-exposed to the real pathogen, the memory WBC produce the correct antibody very quickly - destroys the pathogen quickly, preventing the person being infected
65
Q

Why is it important that a very large number of people are vaccinated against pathogens?

A
  • introduces herd immunity - most people are vaccinated, so they protect the unvaccinated people from being infected
  • this is because there is no one who can pass the pathogen onto the unvaccinated person
66
Q

What are the pros of using vaccinations in the prevention of disease?

A
  • vaccines eradicated many infectious diseases that were once common and deadly e.g. smallpox and polio
  • epidemics are prevented through herd immunity - reduces death and costs of diseases
67
Q

What are the cons of using vaccinations in the prevention of disease?

A
  • don’t always work - not effective in providing immunity
  • side effects - some people may react badly to particular vaccines
    e.g. swelling or fevers (however rare)
68
Q

How do antibiotics treat disease?

A
  • are medicines that help to cure bacterial disease
  • can be taken as a pill, syrup or directly into the bloodstream
  • kills infective bacteria inside the body without damaging body cells
  • different antibiotics are effective against different types of bacteria - receiving the correct one is important
  • cannot destroy viruses
    e.g. penicillin
69
Q

What only treats the symptom of the disease?

A
  • painkillers are drugs that relieve pain - reduces symptoms
  • do not kill the pathogen
    e.g. aspirin
70
Q

What are the problems with antibiotics?

A
  • bacteria are becoming resistant to antibiotics
  • mutations can occur during reproduction - results in certain bacteria no longer
    being killed by antibiotics
  • when these bacteria are exposed to antibiotics, only the non-resistant one die
  • resistant bacteria survive and reproduce - population of resistant bacteria increases
  • antibiotics that were previously effective no longer work
  • resistant strain could cause a serious infection that can’t be treated by antibiotics
    e.g. MRSA causes serious wound infections, resistant to meticillin
71
Q

How can we prevent the development of resistant strains in antibiotics?

A
  • stop overusing antibiotics - unnecessarily exposes bacteria to the antibiotics
  • finishing courses of antibiotics to kill all of the bacteria
72
Q

Why is it difficult to kill viruses?

A
  • difficult to develop drugs that kill viruses without also damaging the body’s tissues
73
Q

How are plants used as drugs?

A
  • plants produce a variety of chemicals to defend themselves against pests and pathogens
  • these chemicals can be used as drugs to treat human diseases or relieve symptoms
74
Q

Name drugs traditionally extracted from plants

A
  • Aspirin is used as a painkiller - originates from willow
  • Digitalis is used to treat heart conditions - originates from foxglove
75
Q

How was penicillin discovered?

A
  • Alexander Fleming was growing bacteria on plates
  • he found mould (Penicillium mould) on his culture plates with clear rings
    around the mould - indicated there was no longer any bacteria there
  • found that the mould was producing a substance called penicillin, which
    killed bacteria
76
Q

How are most new drugs made?

A
  • are synthesised by chemists in the pharmaceutical industry
  • however, the starting point may still be a chemical extracted from a plant
77
Q

What are the cautions for new medical drugs?

A
  • new medical drugs have to be tested and trialled before being used
  • to check that they are safe and effective
78
Q

What are new drugs extensively tested for?

A
  • toxicity - how harmful it is
  • efficacy - whether the drug works and produces the effect you’re looking for
  • dose - the concentration that should be given, and how often it should be given
79
Q

What is preclinical testing?

A
  • uses cells, tissues and live animals
  • to test efficacy, find out about its toxicity, and find the best dosage
  • some people think it’s cruel, however is the safest way
80
Q

What is clinical testing?

A
  • using volunteers and patients
81
Q

How do clinical trials take place?

A
  • first, it’s tested on healthy volunteers with a low dose to ensure there are no harmful side effect
  • if safe, further clinical trials are carried out to find the optimum dose for the drug
  • to test how well it works, patients are split into two groups
  • one group receives the drug and one receives a placebo - so the effect of the new drug can be observed
  • can be single-blind or double-blind
  • before results are published, they are peer reviewed to check for repeatability - prevents false claims
82
Q

What is the placebo effect?

A
  • when the patient expects the treatment to work and so feels better, even though the treatment isn’t doing anything
83
Q

How can a placebo be given?

A
  • as a sugar pill
84
Q

What are double blind trials?

A
  • neither the patient or doctor knows
    whether they are receiving the drug
  • removes any biases the doctor may
    have when they are recording the results
85
Q

What are monoclonal antibodies?

A
  • are identical antibodies, that have been produced from the same immune cell
  • ability to bind to only one protein antigen - means they can be used to target chemicals and cells in the body
  • have many different medical uses
    e.g. pregnancy testing.
86
Q

How are antibodies produced?

A
  • by a type of WBC called a B-lymphocyte
87
Q

What do lymphocytes produce?

A
  • antibodies that are used against anything that the body detects as foreign (has a foreign antigen)
88
Q

What is an antigen?

A
  • a protein on the surface of all cells, specific to each cell
  • WBC can detect when a foreign antigen of a pathogen is present
89
Q

How do you produce monoclonal antibodies?

A

1) mice are injected with desired antigen to simulate lymphocytes to produce antibodies specific to the antigen
2) lymphocytes are collected from the mice - produces antibodies but do not divide
3) combined with tumour cells - do not produce antibodies but divide rapidly
4) a hybridoma is formed - produces antibodies and divides rapidly through mitosis
5) hybridoma is left to produce clones of itself and produce lots of antibodies
6) antibodies are collected and purified

90
Q

What is present in a pregnant woman’s urine?

A
  • a hormone called human chorionic gonadotrophin (hCG)
91
Q

How are monoclonal antibodies used in pregnancy tests?

A
  • there are two sections of the stick.
  • the first section has mobile antibodies complementary to the hCG hormone - also attached to blue beads.
  • the second section has stationary antibodies complementary to the
    hCG hormone - stuck down to the stick.
    1) the individual urinates on the first section - if hCG is present it binds to the mobile antibodies attached to blue beads to form hCG/antibody complexes.
    2) are carried in the flow of liquid and moves up the stick to the second section.
    3) the stationary antibodies then bind to the HCG/antibody complexes - as they are bound to a blue bead, it results in a blue in
    4) this indicates that you are pregnant
    5) if not, urine still moves up, but there is nothing to stick the blue beads onto the test strip - doesn’t go blue
92
Q

What are found in cancer cells?

A
  • have antigens on their cell membranes that aren’t found on normal body cells
  • known as tumour markers
93
Q

How are monoclonal antibodies used to treat diseases?

A
  • producing monoclonal antibodies that bind to the tumour markers, - stimulates the immune system to attack the cell
  • binds to receptor sites on the cell surface membrane of the cancer cells - growth-stimulating molecules cannot bind, stopping the cell from dividing.
  • used to transport toxic drugs, chemicals or radioactive substances as they can only bind to cancer cells - doesn’t kill normal body cells
94
Q

How are monoclonal antibodies used in laboratories?

A
  • can be used to measure and monitor levels of hormones or chemicals in the blood.
    1) monoclonal antibodies are modified - will bind to the molecule you are looking for.
    2) the antibodies are also bound to a fluorescent dye.
    3) if the molecules are in the sample then the antibodies bind to it, and the
    dye can be observed.
    e.g. screening donated blood for HIV infections.
95
Q

How are monoclonal antibodies used in research?

A
  • to find or identify certain molecules on a cell or tissue
  • the same method as laboratories is used - scientists look for a build up of the fluorescence
96
Q

What are the disadvantages of monoclonal antibodies?

A
  • in certain trials have been found to produce very harmful side-effects - fever. vomiting, low blood pressure
  • aren’t as widely used as everyone hoped for when first developed
  • expensive to develop
  • hard to attach monoclonal antibodies to drugs
97
Q

What are the advantages of monoclonal antibodies?

A
  • only bind to specific cells - healthy cells are not affected
  • able to produce mouse-human hybrid cells to reduce the chance of triggering an immune response
  • can be engineered to treat many different conditions
98
Q

What can plants be attacked by?

A
  • pathogens
    e.g. TMV and rose black spot
  • insects
    e.g. aphids - extract nutrients like sugars from the plant by piercing phloem with their mouthpiece
  • lack of glucose = less amino acids can be produced = less proteins produced = stunted growth
99
Q

What makes up amino acids?

A

*glucose and nitrate ions

100
Q

How can plant diseases can be detected?

A
  • stunted growth - nitrate deficiency
  • spots on leaves - black spot fungus on roses
  • areas of decay (rot) - black spot fungus on roses, blights on potatoes
  • abnormal growths e.g. crown galls - bacterial infection
  • malformed stems or leaves - aphid infestation
  • discolouration - magnesium deficiency, TMV
  • the presence of pests
101
Q

How can plant diseases can be identified?

A
  • reference to a gardening manual or website
  • taking infected plants to a laboratory to identify the pathogen
  • using testing kits that contain monoclonal antibodies
102
Q

What can plants be infected by, and what can plants be damaged by?

A
  • infected by a range of viral, bacterial and fungal pathogens, as well as by insects
  • damaged by a range of ion deficiencies
103
Q

How can plants be damaged by nitrate deficiency?

A
  • nitrate ions are needed to make amino acids - makes proteins by converting sugars made in photosynthesis
  • a lack of nitrate ions means less proteins are synthesised
  • leads to stunted growth in plants
104
Q

How are plants damaged by magnesium deficiency?

A
  • magnesium ions are needed to make chlorophyll,
  • magnesium ion deficiency leads to chlorosis
  • leaves of the plant become yellow
105
Q

Why is the understanding of ion deficiencies important?

A
  • it allows horticulturists (people that cultivate plants) to provide optimum conditions for plants
106
Q

What are the 3 different types of plant defences?

A
  • physical
  • chemical
  • mechanical
107
Q

Name the physical plant defence responses

A
  • strong cellulose cell walls - act as a physical barrier against microorganisms
  • thick, tough waxy cuticle on leaves - stops entry into leaves and their cells from becoming infected by bacteria and fungi
  • layers of dead cells around stems - form a physical barrier against microorganisms and fall off with the pathogens
    e.g. bark
108
Q

Name the chemical plant defence responses

A
  • produce antibacterial chemicals - kills bacteria
    e.g. mint plant, witch hazel
  • produce poisons - deters herbivores
    e.g. foxglove, deadly nightshade
109
Q

Name the mechanical plant defence adaptations

A
  • thorns and hairs - make it difficult and painful to eat, avoid being eaten, doesn’t defend against insects
  • leaves which droop or curl when touched - prevent themselves from being eaten, knock insects off and move away from things
  • mimicry to trick animals
  • some plants droop to look unhealthy
  • plants can have patterns that look like butterfly eggs - butterflies do not lay eggs
    e.g. passion flower
  • stone pebble like appearance - avoide predation
    e.g. ice plant famliy

ZZ Biology P1 (4 decks)

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