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Biology > B3 - Infection And Response > Flashcards

B3 - Infection And Response Flashcards

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1
Q

What are pathogens?

A

Pathogens are microorganisms that cause infectious disease

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2
Q

What are the four types of pathogen?

A

Bacteria
Fungi
Protist
Virus

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3
Q

How do bacteria make us feel ill?

A

Reproduce rapidly in the body
And produce toxins that damage cells

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4
Q

How do viruses make us feel ill?

A

Live and replicate inside cells
Causing cell damage such as cell bursts

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5
Q

What are protists?

A

Single-celled eukaryotes
That are Transferred by a vector

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6
Q

How can pathogens be spread?

A

Water
Air
Direct contact

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7
Q

How can the spread of diseases be reduced or prevented?

A

Hygiene - regular hand washing before preparing food and by disinfecting surfaces

Vaccination of (make specific to question) - to provide (herd) immunity

Isolation - to reduce contact with healthy people

Destroy vectors - by using insecticides for example

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8
Q

What are three types of viral disease?

A

Measles
HIV
Tobacco mosaic virus (TMV)

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9
Q

What are the symptoms of measles?

A

Fever
Red skin rash

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10
Q

How is measles spread?

A

Inhalation of droplets from sneezes and coughs from infected people

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11
Q

How can the spread of measles be reduced or prevented?

A

Most young children are vaccinated against measles

By isolating infected people

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12
Q

What are the symptoms of HIV?

A

Initially a flu-like illness
Often no symptoms for years
If AIDS develops, recurrent infections and longer recovery

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13
Q

How is HIV spread?

A

Sexual contact

Exchange of bodily fluids such as blood when drug users share needles

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14
Q

How can the spread of HIV be prevented or reduced?

A

Antiretroviral drugs control HIV to stop AIDS developing

Avoid sexual intercourse/use a condom

Do not share needles

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15
Q

Unless cured by antiretroviral drugs, how does HIV develop?

A

HIV attacks immune cells

Late stage HIV infection, or AIDS, occurs when the immune system becomes so damaged that it can no longer deal with other infections / cancer

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16
Q

What are the symptoms of TMV?

A

Mosaic pattern of discolouration on leaves

Restricted growth due to lack of photosynthesis

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17
Q

How is TMV spread?

A

Direct contact between diseased / healthy plants

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18
Q

How can the spread of TMV be reduced or prevented?

A

Remove infected plants / their leaves

Wash tools in disinfectant after using them on an infected plant

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19
Q

Explain why TMV causes restricted growth in tomatoes (any plant species)

A

Parts of the leaves have no chlorophyll
So less light energy is absorbed for photosynthesis
Therefore less glucose made from photosynthesis
And so less proteins made from glucose for growth

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20
Q

Why do Antibiotics not treat HIV, measles or tobacco mosaic virus?

A

Antibiotics are only effective against bacteria as they do not kill viruses

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21
Q

Suggest reasons for the decrease in the number of new HIV cases in recent years

A

Better education into the prevention of spread of HIV

Condoms more widely available, easier to source or cheaper

More effective drugs and antiretrovirals to prevent HIV spread

More testing and identification of people with HIV

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22
Q

What is one disadvantage to using antiretroviral drugs to treat HIV?

A

They do not eliminate HIV completely, so are not considered a cure

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23
Q

What are two bacterial diseases?

A

Salmonella food poisoning and gonorrhoea

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24
Q

What are the symptoms of salmonella food poisoning?

A

Fever, abdominal cramps, vomiting and bacteria due to toxins secreted by bacteria

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25
Q

How is salmonella food poisoning spread?

A

Through bacteria ingested in foods such as chicken, or on food prepared in unhygienic conditions

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26
Q

How can the spread of salmonella food poisoning be reduced or prevented?

A

In poultry, for example, vaccinate chickens, so fewer bacteria are in chicken and its eggs so fewer bacteria is ingested by humans

Wash hands before preparing food and disinfect surfaces

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27
Q

What are the symptoms of gonorrhoea?

A

Thick yellow or green discharge from the vagina or penis

Pain during urinating

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28
Q

How is gonorrhoea spread?

A

Sexually transmitted disease so spread by sexual contact

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29
Q

How can the spread of gonorrhoea be reduced or prevented?

A

Use of barrier methods of contraception such as condoms

Was easily treated by the antibiotic penicillin until many resistant strains of gonorrhoea appeared

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30
Q

Suggest why the number of cases of salmonella food poisoning is usually higher in summer than in winter

A

Warmer weather so bacteria reproduce faster

Food not cooked properly on barbecues

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31
Q

Other than vaccination, suggest how farmers could prevent the transmission of salmonella from chickens to humans

A

Give chickens antibiotics
Do not sell infected chickens and their eggs
Keep infected chickens isolated
Slaughter infected chickens

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32
Q

Name a fungal disease

A

Rose black spot

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33
Q

What are the symptoms of rose black spot?

A

Purple or black spots develop which turn yellow and drop early

34
Q

How is rose black spot spread?

A

By wind/water

35
Q

How can the spread of Rose blackspot be prevented or reduced?

A

Using fungicides or removing affected leaves

36
Q

What is the effect of rose black spot on plant species?

A

A reduction in the rate of photosynthesis, causing stunted growth

37
Q

Name a protist disease

A

Malaria

38
Q

What is a symptom of malaria?

A

Repeating episodes of fever that can be fatal

39
Q

Describe how mosquitoes are vectors

A

Mosquitoes pick up the malarial protest when they feed on infected animals

40
Q

How can the spread of malaria be prevented or reduced?

A

Preventing vectors (mosquitoes) from breeding, using insecticides, using mosquito nets to avoid being bitten and killing mosquitoes

41
Q

Describe the non-specific defence systems of the human body that prevent the entry of pathogens

A

The skin is tough, dry, has a dead outer layer and platelets form scabs over cuts. This acts as a barrier. The skin has antimicrobial secretions that kill pathogens. The skin has sebum that repels pathogens

The nose has hair and mucus that traps pathogens that enter

The trachea and bronchi produce mucus that traps pathogens breathed in and contain cilia that waft mucus up to the throat to be swallowed

The stomach contains hydrochloric acid that kills most pathogens in food or swallowed mucus

The eyes produce antiseptic tears that contain enzymes to kill bacteria

42
Q

Explain the role of the immune system in the defence against disease

A

If a pathogen enters the body after passing non-specific defence systems, the immune system tries to destroy the pathogen.

  • White blood cells ingest pathogens by phagocytosis. White blood cells can change shape to engulf pathogens and destroy them by secreting enzymes
  • B-Lymphocytes produce antibodies which help destroy pathogens by binding to specific antigens on the pathogen.
  • White blood cells produce antitoxins to counteract and neutralise the toxins released by pathogens by binding to toxic molecules to prevent them from damaging cells
43
Q

What are the three ways white blood cells help to defend against pathogens?

A

Phagocytosis
Antibody production + memory cells
antitoxin production

44
Q

Define vaccination

A

Introducing small quantities of dead, inactive (specific) pathogens into the body to stimulate the release of antibodies from white blood cells.

45
Q

What are the advantages and disadvantages of vaccination?

A

Vaccines have helped control many communicable diseases and they mean that epidemics can be prevented

However, vaccines are not always effective as they don’t always work and individuals may have bad reactions to it

46
Q

Explain how immunisation protects us from a named disease

A

The name disease can be measles, malaria and MMR

A dead or inactive form of the pathogen is injected. The body produces specific antibodies to the antigen on the surface of the pathogen. Memory cells for the antigen on the surface of the pathogen are produced. If the same pathogen enters the body again, memory white cells recognise the pathogens, and produce antibodies rapidly

47
Q

What are antibiotics?

A

Antibiotics, such as penicillin, are medicines that help to cure bacterial disease by killing infected bacteria inside the body

48
Q

It is important that specific bacteria should be treated by specific antibiotics

A

!

49
Q

The use of antibiotics has greatly reduced deaths from infectious bacterial diseases. However, what is the growing concern?

A

The emergence of strains resistant to antibiotics

50
Q

What can antibiotics not kill?

A

Viral pathogens

51
Q

What are painkillers used for?

A

To treat the symptoms of the disease, but do not kill pathogens

52
Q

Why is it difficult to develop drugs that kill viruses?

A

Because it may damage the bodies tissues

53
Q

Explain why antibodies cannot treat viral infections

A

Viruses are found in the host cell. antibodies cannot get inside the cell. They only target and destroy bacterial cells

54
Q

Name two antibiotics

A

Amoxicillin and penicillin

55
Q

Where does the heart drug digitalis originate from?

A

Foxgloves

56
Q

Where does the painkiller aspirin originate from?

A

Willow

57
Q

Where does penicillin originate from?

A

Discovered by Alexander Fleming from the penicillium mould

58
Q

Most new drugs are synthesised by chemists in the pharmaceutical industry. however, the starting point may still be a chemical extracted from a plant

A

!

59
Q

Students should be able to describe the process of discovery and development of potential new medicines

A

!

60
Q

Why do new medical drugs have to be tested and trialled before use?

A

To check they are safe and effective

61
Q

What are new drugs tested for?

A

Toxicity, Efficacy and dose

62
Q

What is a placebo?

A

A tablet or injection with no active drug in it

63
Q

Explain how vaccines work for populations

A

Through herd or community immunity

If an outbreak occurs, if there is a greater proportion of people immunised against the disease, the less likely it is to spread. A vaccinated population effectively isolates the unvaccinated people from contracting or transmitting disease.

64
Q

What is a monoclonal antibody?

A

An antibody made by cloning a white blood cell

65
Q

Describe how monoclonal antibodies are produced (6)

A

Inject a mouse with chosen antigen from pathogen
This will stimulate the production of antibodies from B-lymphocytes. This is because the antigen is specific to the antibody
Isolate the lymphocytes that produce the specific antibody from the mouse
Fuse the lymphocytes with tumour cells to form a hybridoma
Clone this
The hybridoma divides rapidly and produces many identical antibodies that are harvested and purified

66
Q

Explain why monoclonal antibodies are useful

A

Monoclonal antibodies are produced from single clone of cells

The antibodies are specific to one binding site on one protein antigen

So are able to target a specific antigen chemical or cell in the body

67
Q

What are some of the uses of monoclonal antibodies?

A

For diagnosis, such as in pregnancy tests

In laboratories to measure the levels of hormones and other chemicals in blood

To detect pathogens

To treat some diseases such as cancer

In research to locate or identify specific molecules in a cell tissue by binding to them with a fluorescent dye

68
Q

Describe how monoclonal antibodies can treat diseases

A

The monoclonal antibody can be bound to a radioactive substance, a toxic drug or a chemical

The mAb will only target diseased/cancerous cells as it is complementary without harming other cells in the body

This stops the Diseased/cancerous cells from growing and dividing as it blocks growth receptors

69
Q

Describe how monoclonal antibodies are used in pregnancy tests

A
70
Q

Why are monoclonal antibodies so powerful?

A

Powerful research tool as they can be made specific to any antigen

71
Q

Describe how monoclonal antibodies and a fluorescent dye could be used to detect pathogens on a slide

A

Bind the fluorescent dye to the monoclonal antibodies

Put the bound dye on the slide and rinse off

mAbs will bind to the antigens on the Candida albicans pathogen and the dye will make it identifiable under the microscope

72
Q

Explain how increased phagocytosis of the Candida Albicans pathogen will help the patient

A

The pathogen will be engulfed by pathogens
So there is less damage to cells

73
Q

How can plant diseases be detected? (7)

A

Stunted growth
spots on the leaves
areas of decay
growths
malformed stems or leaves
discolouration
Presence of pests

74
Q

How can plant diseases 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 (this could be an application question)

75
Q

What does nitrate deficiency and magnesium deficiency result in?

A

Nitrate deficiency results in stunted plant growth

Magnesium deficiency results in chlorosis (yellow leaves)

76
Q

What are the physical defence responses to resist the invasion of microorganisms in a plant?

A

Cellulose cell walls
Tough waxy cuticle leaves
Layers of dead cells around stems and bark on trees which fall off

77
Q

What are chemical plant defence responses?

A

Antibacterial chemicals
Poisons that deter herbivores

78
Q

What are mechanical adaptations of a plant?

A

Thorns and hairs that deter animals. Nettles have specialised hairs that act as hypodermic needles, injecting poison

Leaves that droop or curl when touched
Mimicry to trick animals

79
Q

Explain how clinical trials are carried out

  • What is the purpose of placebos and double blind trials?
A
80
Q

Suggest two advantages of using a vaccine made of only a small part of the virus, rather than a weakened form of the whole virus

A

Still contains the antigen for stimulating the release of antibodies

It is safer and there is no risk of contracting disease as viruses CANNOT reproduce

81
Q

Why do vaccinations contain a small quantity of dead or inactive pathogens instead of live forms?

Explain why diseases can still be prevalent in countries, even if many people are vaccinated against it

A

Contains the antigen responsible for stimulating the release of antibodies by B-lymphocyte, yet does not cause illness or symptoms

Disease could be spread easily by sneezing or coughing and antibiotics may not be available or too expensive

82
Q

Explain how MRSA bacteria have evolved to become resistant to antibiotics

(this can be any named bacteria)

A

Bacteria reproduce rapidly every 20 minutes by binary fission

Mutations of bacterial pathogens can produce new strains

The non-resistant strains are killed and reduce competition

Certain MRSA strains may be resistant to antibiotics and so are not killed

These strains survive and reproduce, so the population of the resistant strain increases

The resistant stain will continue dividing and spread because people are not immune to it and there’s no treatment

Biology (9 decks)

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