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GCSE Biology > Topic 3 - Infection and Response > Flashcards

Topic 3 - Infection and Response Flashcards

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1
Q

What is a pathogen?

A

Pathogens are microorganisms that enter the body and cause disease. They cause communicable (infectious) diseases - diseases that can be spread. Both plants and animals can be infected by pathogens.

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2
Q

8 key facts about Bacteria

A
  • Prokaryotes
  • Single celled organisms
  • Don’t have a true nucleus, but a circular strand of DNA
  • Do not contain mitochondria
  • Have a tail, known as a flagella, to help it move
  • Produce toxins that damage cells and tissues
  • Living cells
  • Largest bacteria are 10 micrometers long
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3
Q

6 Key facts about Viruses

A
  • Not cells
  • Much smaller than bacteria
  • Reproduce rapidly inside host cells
  • Viruses consist of genetic material and a protein coat
  • Once inside a cell, viruses can make thousands of copies of itself, this continues until the host cell bursts open
  • Cell damage is what makes humans feel unwell
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4
Q

4 Key facts about Protists

A
  • eukaryotes
  • single celled organisms
  • can be parasitic, means they live on or in side another organism causing harm
  • can be animal like, plant like, or fungi like
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5
Q

6 Key facts about Fungi

A
  • single celled fungus => yeast
  • multicellular fungus => toadstools, mushrooms, and mould
  • cell walls are made from chitin
  • use saprotrophic nutrition, they secrete enzymes to digest food and then absorb it
  • threadlike structures called hyphae
  • hyphae can produce spores, enabling the fungus to be easily spread
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6
Q

What 4 ways are pathogens spread?

A
  • Water
  • Air
  • Direct Contact
  • Indirect contact
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7
Q

How are measles transmitted?

A

Spread through droplets from an infected persons cough.

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8
Q

What are the symptoms of measles?

A

Red skin rash, signs of a fever

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9
Q

What causes measles?

A

a virus

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10
Q

How do you treat/prevent measles?

A

Vaccinations at a young age.

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11
Q

How is Rose Black Spot transmitted?

A

Spreads through the environment in water or by the wind.

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12
Q

What are the symptoms of Rose Black Spot?

A

Causes purple/black spots to develop on the leaves, which can then turn yellow and drop off.

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13
Q

What causes Rose Black Spot?

A

a fungus

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14
Q

How can Rose Black Spot be treated/prevented?

A

Can treat the plant by using fungicides, and by stripping the plant of affected leaves and burning them because of spores.

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15
Q

How is Malaria transmitted?

A

Mosquitos pick up the malaria protist when they feed on infected animals - every time it feeds on another animal, it infects it by inserting the protist into the animals blood vessels.

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16
Q

What are the symptoms of Malaria?

A

Repeating episodes of fever

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17
Q

What is the cause of Malaria?

A

a protist

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18
Q

How can Malaria be treated/prevented?

A

Spread can be reduced by stopping mosquitos from breeding, people can also be protected from bites.

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19
Q

How is Tobacco Mosaic transmitted?

A

By contact between plants

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20
Q

What are the symptoms for Tobacco Mosaic?

A

Causes a mosaic pattern on the leaves of the plant, parts of the leaves become discoloured.

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21
Q

What causes Tobacco Mosaic?

A

a virus

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22
Q

How can Tobacco Mosaic be treated/prevented?

A

Dig up and destroy infected plants.

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23
Q

How is Salmonella transmitted?

A

Can get it by eating food that’s been contaminated with salmonella bacteria.

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24
Q

What are the symptoms of Salmonella?

A

Fever, stomach cramps, vomiting and diarrhoea

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25
Q

What causes Salmonella?

A

a bacteria

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26
Q

How can Salmonella be treated/prevented?

A

In the Uk most poultry are given vaccinations, stopping the spread of bacteria and people from getting the disease.

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27
Q

How is Gonorrhoea transmitted?

A

Sexual contact, e.g. unprotected sex

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28
Q

What are the symptoms of Gonorrhoea?

A

Pain while urinating, thick yellow/green discharge from penis or vagina.

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29
Q

What causes Gonorrhoea?

A

a bacteria

30
Q

How can Gonorrhoea be treated/prevented?

A

Treated with antibiotics (penicillin is no longer as effective), prevented with protected sex.

31
Q

How is HIV transmitted?

A

Through sexual contact, or exchange of bodily fluid (blood etc.)

32
Q

What are the symptoms of HIV?

A

Initially flulike symptoms for a few weeks, the person then doesn’t feel symptoms for a few years. It attacks the body’s immune system, meaning it can’t always cope with other infections (cancer etc.)

33
Q

What causes HIV?

A

a virus

34
Q

How can HIV be treated?

A

Antiretroviral drugs stop the virus replicating.

35
Q

What is the cycle of the Protsist disease Malaria?

A
  • Plasmodium = the protist that causes Malaria.
  • Malaria parasite infects the liver and reproduces quickly =>
  • Malaria Parasite in the blood of humans =>
  • Mosquito consumes infected blood when feeding =>
  • Sexual reproduction of the Malaria parasite =>
  • Female Anopheles mosquito bites human => (cycle repeats)
36
Q

What are the 5 Human defence systems?

A
  • Nose; Nasal hair keeps out dust and larger microorganisms. The production of mucus also helps trap pathogens.
  • Skin; Complete barrier against pathogens (unless cut) and produces antimicrobial secretions.
  • Trachea and Bronchi; Both of these produce mucus to catch pathogens and are lined with cilia (hairs).
  • Stomach; Produces hydrochloric acid to kill any pathogens that may enter.
  • White blood cells; phagocytosis, antibodies and antitoxins
37
Q

4 Stages of Phagocytosis

A
  1. The phagocyte identifies a pathogen and attaches itself to it.
  2. Cytoplasm surrounds and engulfs pathogen.
  3. The pathogen is killed and digested.
  4. The indigestible residue is removed.
38
Q

4 Stages of Antibodies Formation

A
  1. Pathogens contain antigens (unique molecules) on their surface.
  2. When Lymphocytes detect these antigens, they produce antibodies in response.
  3. The antibodies lock onto the antigens, rendering them useless.
  4. Lymphocytes can now destroy the pathogens, as it’s easier for them to target pathogens if they are covered in antibodies.
39
Q

3 Stages of Antitoxins Formation

A
  1. Bacteria can produce toxins that are harmful to the human body.
  2. White blood cells detect the toxins and produce antitoxins.
  3. The antitoxins neutralise the effect of toxins.
40
Q

How do vaccines work (6 steps)?

A
  1. A small amount of dead or inactive (or attenuated/weakened) pathogen is injected into the body.
  2. The pathogen has an antigen on its surface.
  3. Lymphocytes detect the antigen as foreign.
  4. Lymphocytes produce antibodies which lock onto the specific antigen, destroying the pathogen.
  5. Memory white blood cells are produced.
  6. If the pathogen reenters the body, antibodies are mass produced very quickly, preventing reinfection.
41
Q

What is Herd Immunity?

A

This involves a high percentage of a population being immune to a disease (due to vaccinations). The disease cannot be passed on because it cannot find a new host and consequently the disease reduces in the population.

42
Q

Who can’t get vaccinations? (4)

A
  • Babies (particularly under 8 weeks)
  • Pregnant women ( can have flu/whooping cough vaccinations)
  • Immunocompromised people, such as those receiving chemotherapy or have had organ transplants
  • People who have life threatening allergic reactions to something in the vaccine
43
Q

What are the pros of vaccinations? (2)

A
  • Vaccines have helped control lots of diseases that were once common in the UK. (E.g. Polio, measles, rubella etc.) Smallpox no longer exists, and polio infections have fallen by 99%.
  • Epidemics can be prevented if a large percentage of the population is vaccinated.
44
Q

What are the cons of vaccinations? (2)

A
  • Vaccines don’t always work - sometimes don’t give immunity.
  • You can sometimes have a bad reaction to a vaccine (e.g swelling, or something more serious like a fever or seizures). Bad reactions are rare.
45
Q

How do you balance the risks of getting vaccinated?

A

The risk of catching the disease if you don’t have a vaccine, against the risk of having a bad reaction if you do have the vaccine. You need to look at the evidence.

46
Q

What are the 2 types of drugs?

A
  • Painkillers; relieve pain. Do not tackle the cause of the disease, just help to reduce the symptoms. (e.g aspirin)
  • Antibiotics; kill/prevent the growth of the bacteria causing the problem without killing your own body cells => specific antibiotics treat specific bacteria. They don’t destroy viruses, as they reproduce using your own body cells, making it hard not to kill your body cells as well.
47
Q

What is an example of a mutated bacteria, resistant to antibiotics?

A

MRSA, a type of bacteria that causes wound infection. It can no longer be treated by the antibiotic methicillin due to its mutations.

48
Q

How does antibiotic resistance work? (3 steps)

A
  1. Non-resistant bacterium and Resistant bacterium are together inside the body.
  2. They are treated with antibiotics, but the resistant bacterium survives.
  3. The population of the resistant bacterium increases due to natural selection.
49
Q

How do you slow down the rate of development of resistant bacteria strains? (2)

A
  • Doctors need to stop overprescribing antibiotics, so they are only given to you for important/more serious things.
  • It is important to finish the course of antibiotics, instead of just stopping them when you feel better.
50
Q

What is the origin of Aspirin?

A

Aspirin = a painkiller and lowers fevers. Developed from a chemical found in willow.

51
Q

What is the origin of Digitalis?

A

Digitalis = used to treat heart conditions. Developed from a chemical found in foxgloves.

52
Q

What is the origin of Penicillin?

A

Discovered by Alexander Fleming. He was clearing out petri dishes containing bacteria, and one of the dishes had grown penicillium mould. The mould was producing a substance that killed the bacteria.

53
Q

What are new drugs tested for? (4)

A
  • Efficiency = do they work the way you want them to?
  • Toxicity = how harmful is it/are they poisonous?
  • Optimum dosage = what concentration and how often is safe, but still works?
  • Side effects = what/how severe are they?
54
Q

What are the 6 stages of drug trials?

A
  1. Scientists, with the aid of computer models, investigate whether a drug can be synthesised.
  2. Scientists test the drugs on human cells/tissues in laboratories - only works if the drug doesn’t affect whole or multiple body systems, e.g blood pressure needs to be tested on animals with intact circulatory systems.
  3. The drugs are tested on animals in a laboratory. Scientists carefully monitor them, looking for side effects, efficiency, toxicity and best dosage.
  4. A low dosage of the drug (which can be gradually increased throughout the trials) is given to healthy volunteers, doctors are looking for harmful side effects.
  5. Patients suffering from the condition are allowed the drug. It is important the drug does what it should, and there are no major side effects. This is also when the optimum dosage is determined.
  6. Having passed all the stages, including peer reviews from other specialists in the field, the drug can be licensed. Medical companies can mass produce the drug and doctors can start prescribing it to patients.
55
Q

What is a placebo?

A

This looks like the drug, but does nothing. It is often a sweet tablet, or an injection containing no drugs.

56
Q

What are blind trials?

A

The patients don’t know who has the the drug and who has the placebo.

57
Q

What are double blind trials?

A

Both the patients and the doctors don’t know who has the drug and who has the placebo.

58
Q

How are Monoclonal Antibodies produced (5 steps)?

A
  1. An antigen is injected into a mouse.
  2. The mouse naturally produces lymphocytes, which produce antibodies specific to the antigen.
  3. Spleen cells which produce the lymphocytes are removed from the mouse during a small operation.
  4. The specific lymphocytes, in a lab, are fused with human cancerous cells (tumour cells) called nyeloma cells to form hybridoma cells which divide indefinitely.
  5. These hybridoma cells divide and produce millions of monoclonal antibodies specific to the original pathogen.
59
Q

How are MABs used in pregnancy tests? (4 steps)

A
  1. Urine is applied to the end of the stick.
  2. Mobile antibodies specific to HCG are found in the reaction zone. They can move and have dye attached to them.
  3. HCG specific immobilised antibodies are found in the result window. If the person is pregnant, and produces a positive test, the immobilised antibodies will bind with the mobile antibodies attached to HCG from the reaction zone. The dye produces a line in the result window.
  4. Immobilised antibodies, specific to the mobile antibodies from the reaction zone are found here. If the test has worked they will bind with the mobile antibodies (that aren’t attached to HCG).
60
Q

How can MABs be used to treat cancer? (5)

A
  • Cancer cells have antigens on their cell membranes that aren’t found on normal body cells, called tumour markers.
  • In the lab, you can make MABs that will bind to the tumour markers.
  • An anticancer drug can be attached to the MABs. This could be a radioactive substance, a toxic drug or a chemical which stops cancer cells growing and dividing.
  • Due to the MABs binding to the tumour markers, the drug kills the cancer cells but not normal body cells near the tumour.
  • The patient receives the MABs through a drip.
61
Q

What are 2 uses of MABs in laboratories with examples?

A
  • MABs can be used to bind hormones and other chemicals in blood to measure their levels, e.g. the ELISA test can be used to detect banned drugs in athletes urine.
  • MABs also used to test blood samples for certain pathogens, e.g. different strains of the pathogen that causes gonorrhoea can be identified using MABs.
62
Q

How can MABs be used in research? (4)

A
  • Can locate specific molecules on a cell or tissue.
  • First MABs are made that will bind to the specific molecule you’re looking for.
  • The antibodies are then bound to fluorescent dye.
  • If the molecules are present in the sample being analysed, the MABs will attach to them and they can be detected using the dye.
63
Q

What is the Problem with MABs?

A

They cause more side effects than were expected, i.e. fevers, vomiting, and low blood pressure. Scientists originally thought they wouldn’t cause any side effects as they target very specific cells/molecules, meaning they aren’t as widely used treatments as expected.

64
Q

What are the 3 types/causes for plant diseases?

A
  • Deficiency diseases; plants need mineral ions from the soil. If there aren’t enough, plants suffer from deficiency symptoms.
  • Diseases caused by pathogens; plants can be infected by viral, bacterial and fungal pathogens.
  • Pest infestations; plants can also be infested and damaged by insects. They are easily spotted as you should be able to see them on the plants.
65
Q

What are 2 examples of plant deficiency diseases?

A
  • Nitrates are needed to make proteins and therefore for growth. A lack of nitrates causes stunted growth.
  • Magnesium ions are needed for making chlorophyll, which is needed for photosynthesis. Plants without enough magnesium suffer from chlorosis (when not enough chlorophyll is made) and have yellow leaves.
66
Q

What is an example of a pest that commonly harms plants?

A

aphids

67
Q

What are 6 common signs a plant has a disease?

A
  • stunted growth
  • spots on the leaves
  • patches of decay (rot)
  • abnormal growth e.g. lumps
  • malformed stems or leaves
  • discolouration
68
Q

How can you identify plant diseases?

A
  • look up the signs in a gardening manual or on a gardening website
  • taking the infected plant to a laboratory, where scientists can identify the pathogen
  • using test kits that identify the pathogens using MABs
69
Q

What are 3 physical plant defences?

A
  • waxy cuticle on stems/leaves
  • cellulose cell walls
  • layer of dead cells around stems
70
Q

What are 2 chemical plant defences?

A
  • antibacterial chemicals
  • posions to deter herbivores
71
Q

What are 3 mechanical plant defences?

A
  • thorns and hairs
  • leaves that droop or curl when touched
  • mimicry (imitating other organisms), e.g. looking like they have an insects egg on them so other insects don’t lay eggs on them, or looking like stones etc.

GCSE Biology (8 decks)

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