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Biology > B5 and B6 Communicable diseases and Preventing and Treating Diseases > Flashcards

B5 and B6 Communicable diseases and Preventing and Treating Diseases Flashcards

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1
Q

What is a communicable disease (or infectious disease)?

A

A disease caused by a pathogen which can be passed between animals or plants eg. flu. What causes the disease is either directly the pathogen or toxins released by it

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2
Q

What is a pathogen?

A

A disease-causing micro-organism eg bacteria, virus, protists, fungi

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3
Q

How do bacteria cause disease?

A

Once inside the body, they divide rapidly by binary fission. They kill cells and produce harmful toxins. Sometimes they directly damage your cells

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4
Q

How do viruses cause disease?

A

They invade and take over the cells in your body and reproduce inside living body cells, leading to cell damage and destruction. Viruses reproduce rapidly by inserting their genetic material into host cells and creating new protein capsules to build new viral particles. Once many copies have been made, the host cell may burst open releasing the viral particles which can go on to infect other cells

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5
Q

Give three ways in which pathogens can be spread

A
  • By air: flu, tuberculosis and common cold are spread by droplet infection. When you are ill you expel tiny droplets full of pathogens when you talk, breathe or sneeze. Other people breathe in the droplets and pick up the infection. Also pathogens in plants can be carried by the wind
  • By water: fungal spores in water spread plant diseases. In humans drinking water contaminated with sewage can cause diseases such as cholera, diaorrahea, salmonellosis
  • By direct contact: sometimes diseases are spread by direct contact between an individual who is infected and an healthy one. This is very common in plants where an infected piece of crop left in a field might destroy and entire crop. Also infections such as hepatitis and ADS enter the body through sexual contact, cut, scratches and needles. Also animals can act as vectors
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6
Q

Give four ways in which the spread of pathogens can be reduced

A

Hygene - handwashing, disinfectants, tissues
Reducing contact with infected individuals- quarantine
Removing vectors: use of pesticides and insecticides, removal of habitats
Vaccination

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7
Q

Why is it important to prevent the spread of viral diseases?

A

Because scientists have not yet developed cures for many viral diseases

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8
Q

What is measles?

A

Measles is a serious viral disease that can cause blindness and brain damage. It is spread by droplets from infected people. The main symptoms are a fever and a red skin rash

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9
Q

How is measles spread?

A

By air through the inhalation of droplets from coughs and sneezes

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10
Q

What is HIV/ AIDS?

A

HIV is a virus which attacks and damages the immune system until it can no longer function properly. AIDS is the condition resulting from a long term HIV infection. There is no cure of vaccine for HIV/AIDS

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11
Q

How is HIV spread?

A

Direct sexual contact and the exchange of bodily fluids eg blood, breastmilk

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12
Q

How can the spread of HIV / AIDS be prevented?

A
  • Condoms
  • Screening of blood transfusions
  • Not sharing needles
  • Bottle feeding by HIV-positive mothers
  • Use of antiretroviral drugs to prevent the development of AIDS
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13
Q

What is tobacco mosaic virus?

A

A plant pathogen which causes leaf discolouration when cells are damaged. Affected areas cannot photosynthesise, reducing the crop yield. As there is no treatment, farmers grow TMV resistant crop strains to avoid infection

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14
Q

How is tobacco mosaic virus spread?

A

Contact between infected and healthy plants. Insects might act as vectors which transfer the virus between different plants

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15
Q

What is salmonella?

A

A type of bacteria found in raw meat, poultry and eggs. If they enter the body, they can affect natural gut bacteria. One common cause for catching it is eating undercooked food.

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16
Q

What are the symptoms of salmonella food poisoning?

A
  • Fever
  • Abdominal cramping
  • Vomiting
  • Diarrhoea
    may be fatal to very young and elderly due to risk of dehydration
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17
Q

How can the spread of salmonella be limited?

A
  • Vaccinating animal intended for consumption
  • Keep raw meat away from cooked meat
  • Disinfect hands and surfaces after contact with raw meat
  • Thoroughly cook meat
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18
Q

What is gonorrhoea?

A

A sexually transmitted bacterial infection caused by unprotected sex with an infected individual. Early symptoms include yellow/ green discharge from genitals and painful urination, although it may be symptomless.
Its spread can be controlled though the use of antibiotics (no longer penicillin as many strains are resistant) and using condoms

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19
Q

What is rose black spot?

A

A fungal disease which causes purple or black spots to develop on rose leaves, It reduces the area of the leaf which is available for photosynthesis and causes leaves to turn yellow and drop prematurely

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20
Q

How is the rose black spot fungus spread?

A

Fungal spores are spread by the wind and in water

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21
Q

How can rose black fungus be treated?

A

Fungicides
Destroying infected leaves

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22
Q

What is malaria?

A

Malaria is a disease caused by protist pathogens. The disease is carried from host to host by mosquitoes, and the protists enter the human bloodstream when the mosquito bites a human. Symptoms include fever and shaking and it can also be fatal

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23
Q

How can the spread of malaria be reduced?

A

Using insecticides
Using insects nets to avoid bites
Prevent mosquito breeding by removing stagnant water
Antimalarial drugs

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24
Q

How does the skin prevent pathogens from entering the body?

A
  • Acts as a physical barrier
  • Scab formation after skin is cut/ wounded
  • Antimicrobial secretions which can kill pathogens
  • Healthy skin is covered with microorganisms that help keep you healthy and acts as an additional barrier
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25
Q

How does the respiratory system prevent pathogens from entering the body?

A

Nose - has hair and mucus which trap pathogens
Trachea and Bronchi have mucus that traps pathogens. Ciliated cells move mucus to the mouth so it can be swallowed

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26
Q

How does the stomach prevent pathogens infecting the body?

A

Secrets hydrochloric acid which kills pathogens present

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27
Q

How do white blood cells protect us against disease?

A

White blood cells help to defend against pathogens by:
Phagocytosis: Phagocytes engulf and digest pathogens, this can be non-specific or helped by antibodies which cause agglutination (clumping) of pathogens. The phagocyte surrounds the pathogen and releases enzymes to digest and break it down to destroy it
Production of antibodies
Production of antitoxins (these are special types of antibody)

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28
Q

How does antibody production protects us against disease?

A

White blood cells produce special chemicals called antibodies. These target a specific virus or bacteria and kill it. You need a unique antibody for each type of pathogen.
In the case of a second infection, the correct antibodies can be produced rapidly, preventing the person from getting the same disease again

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29
Q

How does antitoxin production protect us from disease?

A

Antitoxins bind to toxins released by pathogens and neutralise them

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30
Q

What is a vaccination?

A

Contains a dead or inactivated form of the pathogen which stimulates white blood cells to produce complementary antibodies to the pathogen. In the case of a second infection, memory cells can rapidly produce the correct antibodies and prevent illness

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31
Q

What is herd immunity?

A

If a sufficient high proportion of a population are immune to a disease (especially through vaccination), the spread of the disease will be limited

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32
Q

What are the advantages of vaccination?

A
  • The have eradicated many deadly diseases eg smallpox
  • Many epidemics can be prevented by vaccinations
  • Herd immunity protects those who cannot have vaccinations
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33
Q

What are the disadvantages of vaccinations?

A
  • Not guaranteed to work - might not protect against multiple strains of a pathogen
  • May have side effects or adverse reactions
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34
Q

What drugs are used to cure some bacterial diseases?

A

Antibiotics they can kill bacterial pathogens inside the body

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35
Q

How do antibiotics work?

A

Antibiotics (eg. penicillin) kill bacterial pathogens inside the body, but do not kill human cells. Whilst some antibiotics kill a wide range of bacteria, it is important that the right antibiotic is used for specific bacteria

36
Q

Why can antibiotics not be used to treat viral diseases?

A

Antibiotics have no effect on viral pathogens as they live inside the hosts’s (human) cells. Therefore, it is difficult to design drugs that would kill the virus and not destroy the human cell at the same time

37
Q

What is antibiotics resistance?

A

The use of antibiotics has increased exponentially since they were first introduced in the 1930s. However, since their discovery and widespread use, antibiotics have been
overused and antibiotic resistance has developed in many different types of bacterial species
Bacteria, like all organisms, have random mutations in their DNA
One of these mutations may give them resistance to an antibiotic
If an organism is infected with bacteria and some of them have resistance,
they are likely to survive treatment with antibiotic
The population of the resistant bacteria will increase
If the resistant strain is causing a serious infection then another antibiotic will
be needed
This is concerning as some types of bacteria are becoming resistant to all known antibiotics so the disease they cause cannot be cured

38
Q

How can we prevent antibiotic resistance?

A
  • avoid overuse and unecessary use of antibiotics (eg do not use antibiotics for viral infections
  • finish antibiotic course to ensure the bacteria is killed
39
Q

What effect do painkillers have on infectious disease?

A

They can treat the symptoms but not kill pathogens

40
Q

What plant is the heart drug digitalis extracted from?

A

Foxgloves

41
Q

What painkiller originates from a compound found in willow bark

A

Aspirin

42
Q

What antibiotics was discovered by A. Fleming from a type of mould?

A

Penicillin

43
Q

What are the four qualities of a good medicine?

A
  • Effective
  • Safe
  • Stable
  • Able to be taken in and removed easily
44
Q

What are the three main factors which are tested when developing a new drug?

A
  • Toxicity
  • Efficacy
  • Dose
45
Q

How is preclinical testing carried out?

A

In a laboratory - it uses cells, tissues and live animals

46
Q

How is clinical testing carried out?

A

It uses healthy volunteers and patients. Firstly, the drug is tested at a low dose on healthy people- then tested on patients and on a larger scale to find the optimum dose. Often, one group receives a placebo (not the test drug) and the other group receives the actual drug, in order to assess its efficacy

47
Q

What is the difference between and single blind and a double blind trial?

A

IN a single blind trial only the doctor knows whether the patient is receiving the drug or the placebo. In a double blind trial neither the patient nor the doctor knows. Double blind trials help remove bias on the part of the doctor

48
Q

What is a peer review?

A

Where the results of drug trials are checked over by scientists knowledgeable in the field

49
Q

What are non communicable disease?

A

Diseases that cannot be transmitted from on person to another eg heart disease, cancer

50
Q

Apart from diseases what else can affect health?

A
  • Diet: if you do not get too much to eat or not the right nutrients you may suffer from diseases ranging from starvation to anemia or rickets. Too much food or wrong type of food can lead to issues such as obesity, type 2 diabetes and some forms of cancer
  • Stress: scientists are linking too much stress to the risk of developing a wide range of health problems, eg certain cancers, heart disease, mental health issues
  • Life situations such as: where in the world you live, gender, financial status, ethnic group, level of free health care provided by the country you live in, how many kids you have, local sewage and rubbish disposal
51
Q

What are the most common pathogens in animals and plants?

A

Animals: virus and bacteria.
Plants: funghi and virus

52
Q

Why do scientists culture microorganism?

A

Culturing microorganisms means growing them in large numbers. Scientists do this to study them. Eg they study what nutrients they need to grow and what chemicals kill hem. Bacteria are the most commonly cultured as they divide rapidly

53
Q

Are all bacteria harmful?

A

No. Not all bacteria are harmful (so not all bacteria are pathogens) – both the skin and
large intestine, in particular, are home to hundreds of different bacterial species
that play a vital role in maintaining our health
Bacteria on the skin act as competitors to harmful pathogens
Bacteria in the large intestine digest substances we can’t in food (such as
cellulose) and provide essential nutrients (such as Vitamin K)

54
Q

How do scientists culture microorganisms?

A

You need to provide them with everything they need:
- Giving them a liquid or gel containing nutrients, a culture medium. This contains carbs, minerals and a nitrogen source so they can make proteins
- some need warmth and oxygen to grow
- hot agar gel is poured into a petri dish. this is left to cool and set before adding the microorganism.
- you need uncontaminated cultures to investigate the effects of chemicals such as disinfectants or antibiotics. It is important to avoid contamination.

55
Q

Why great care is needed when culturing microorganisms?

A

What you grow might be harmless but a genetic mutation could happen to produce a dangerous pathogen

56
Q

Why in school and colleges the max temp at which microorganisms are incubated in 25 degrees even though this is not the optimum temperature for them to grow?

A

if you cultured them at 37 degrees (human body temperature) you might run the risk of growing some dangerous pathogens for humans. Lower temperatures reduce risks for humans. Hospitals and labs grow them at higher temperatures

57
Q

Why are microorganisms incubated at much higher temperatures in labs or industrial platns?

A

to grow more rapidly

58
Q

How do bacteria reproduce and what are the optimum conditions for their reproduction?

A

They grow rapidly by binary fission (ie they split in two). In certain optimum conditions, some bacteria can reproduce rapidly (with the fastest being once every 20 minutes for some species of coli). Optimum conditions usually involve warmth, moisture and a supply of nutrients, oxygen levels and Ph

59
Q

How do you calculate the number of bacteria growth in a population?

A

See pg 80 Biology book

60
Q

How can bacterial growth be limited?

A
  • Raise or lower temperature
  • use of chemicals
61
Q

What is the difference between antiseptic, disinfectant and antibiotics?

A

Disinfectants are chemicals used to kill bacteria in the environment around us
Antiseptic is a disinfectant safe to use on human skin
Antibiotics are chemicals that are safe to use inside our bodies.

62
Q

How do you investigate the effect of disinfectants and antibiotics on bacterial growth?

A

Use agar plate and calculate area See pg 81

63
Q

Are fungal diseases common in humans?

A

Few fungal diseases that affect humans, one example is athletes’ foot. This is spread by contact with surfaces that have been touched by an infected person, such as shower room floors

64
Q

How do fungi work?

A

Often the fungus is unicellular, as in the case of yeast, but can have a body made up of thread-like structures called hyphae
The hyphae can grow and penetrate the surface of plants and animals causing infections
The hyphae can produce spores, which can spread the infection to other organisms
Fungal infections are more common in plants and can destroy a crop or plant

65
Q

What are protists?

A

Protists are a diverse group of eukaryotic and usually unicellular organisms. Only a small number of protists are pathogenic, but the diseases they cause are
often serious. Often need a vector to transfer from one host to the next

66
Q

What are non-specific defence systems of the human body against pathogens?

A

The skin
The nose
The trachea and bronchi
The stomach

67
Q

What is the difference between antigen, antibody and antitoxin

A

Make sure you know the difference between antigen, antibody and antitoxin:
An antigen is a molecule found on the surface of a cell
An antibody is a protein made by lymphocytes that is complementary to
an antigen and, when attached, clumps them together and signals the
cells they are on for destruction
An antitoxin is a protein that neutralises the toxins produced by
bacteria

68
Q

Why is it more difficult to develop medicines against viruses than it has been to develop antibiotics?

A

Since viruses reproduce inside the cell, it is difficult to develop drugs that can destroy viruses without damaging the body cell

69
Q

Does an antibiotics work with any type of bacteria?

A

Only certain antibiotics will work on certain diseases, however, so a doctor will prescribe different antibiotics depending on the type of infection

70
Q

Drugs and plants

A

Traditionally drugs were extracted from plants and microorganisms
New drugs are being developed all the time by scientists at universities and drug
companies around the world
Lots of the medications that we use today are based on chemicals extracted from
plants
The heart drug digitalis originates from foxgloves
The painkiller aspirin originates from willow
Penicillin was discovered by Alexander Fleming from the Penicillium mould
Most new drugs are synthesised by chemists in the pharmaceutical industry.
However, the starting point may still be a chemical extracted from a plant

71
Q

Origin of penicillin

A

Penicillin was first discovered by Alexander Flemming in 1928. He left some Petri dishes that had been contaminated with mould and found the bacteria would not grow near the mould
He discovered that the mould (Penicillium notatum) was releasing a chemical (penicillin) that killed the bacteria surrounding it

72
Q

What are monoclonal antibodies?

A

They are an identical batch (clone) of a single (mono) antibody. Each type is specific to one binding site on a specific antigen so they target specific cells in the body or chemicals

73
Q

How are monoclonal antibodies produced?

A

They are produced by stimulating mouse lymphocytes to make a particular antibody by exposing them to an antigen.
The lymphocytes are combined with a particular type of tumour cell to make a hybridoma cell
(Tumour cells can divide repeatedly which is why they are used)
The hybridoma cell can both divide and produce the antibody
Single hybridoma cells are cloned, resulting in many divisions, making high quantities of identical cells that all produce the same antibody
A large amount of the antibody can be collected and purified ready for use
The cells produced in this way create only one type of antibody, hence the name ‘monoclonal antibodies’.

74
Q

Uses of monoclonal antibodies

A

Monoclonal antibodies have a variety of uses. Some examples include:
- In pregnancy tests
- In laboratories to measure the levels of hormones and other chemicals in blood (such as some cancer proteins), or to detect pathogens. They can be used to measure and monitor levels of hormones or chemicals in the blood. An example is screening donated blood for HIV infections.
- In research to locate or identify specific molecules in a cell or tissue by binding to them with a fluorescent dye
- To treat some diseases: for cancer the monoclonal antibody can be bound to a radioactive substance, a toxic drug or a chemical which stops cells growing and dividing. It delivers the substance to the cancer cells without harming other cells in the body

75
Q

How does a pregnancy test work?

A

A hormone called human chorionic gonadotrophin (hCG) is present in the urine of women who are pregnant.
Monoclonal antibodies in the test bind to these hormones if they are present and the test stick changes colour

76
Q

Advantages and disadvantages of monoclonal antibodies

A

Monoclonal antibodies have the potential to make big improvements to diagnosis and treatment and when they were first developed there were hopes for their use to become widespread. However
CONS
- monoclonal antibodies create more side effects than expected which has hampered their use. This is because mouse cells are used. To improve this scientists are now using mouse- humans hybrid cells. Also doctors are now prepared for side effects and treat the symptoms
- rather expensive to produce
- It has proved harder than expected to bind MAB to drugs. Although new technologies have alleviated this issue
PRO
- they only bind to the specific disease or damaged cell needing treatment. Healthy cells are not affected. In contrast conventional drugs treatment is carried out on the whole body in the blood and can have devastating effects also on healthy cells (think of cancer treatment)

77
Q

How can MAB treat cancer?

A
  • Direct use of MAB to trigger the immune system to recognise, attack and destroy cancer cells
  • Use MAB to block receptors on the surface of cancer cells and so stop the cell from growing a dividing
  • MAB can be used to carry toxic drugs or radioactive substances for radiation therapy, or chemicals which stop the cell from growing. This attacking tumor cells only and not healthy cells.
78
Q

How do aphids cause damage to plants?

A

They use their sharp mouthparts to extract sap from the plant phloem, weakening the plant. They are also vectors who can transfer diseases from infected to healthy plants

79
Q

How can we reduce the number of aphids?

A
  • chemical pesticide
  • Biological pest control using ladybirds
80
Q

Why are nitrate ions needed by plants?

A

They are needed to convert sugars into proteins. If the are not enough the growth will be stunt

81
Q

Why do plants need a good supply of magnesium ions?

A

Magnesium ions are needed to synthesise clorophyll, which absorbs light energy during photosynthesis. A deficit can cause the plant not to photosinthetise properly and leaves turn yellow

82
Q

What are the symptoms of disease in plants?

A
  • Stunted growth (lack of nitrate ions)
  • spotted leaves
  • pests
  • decay/ rot
  • malformations of stem/ leaves
  • discolouration
83
Q

How can plant disease be identified?

A
  • gardening website
  • MAB test kit
  • Lab test
84
Q

Examples of physical defence responses of plants

A
  • Cellulose cell wall strenghten the plant and also helps to resists invasion from microorganisms. That is why the action of aphids breaking the cell wall is so damaging, because it lets pathogens inside
  • tough waxy cuticle on the surface of leaves
  • bark on trees and layer of dead cells on the outside of stems
  • Leaf fall in autumn
85
Q

Examples of chemical defence responses of plants

A
  • many plants produce antibacterial chemicals (scientists are now investigating these to see if they could used for humans as well since the effect of antibiotics is decreasing)
86
Q

Examples of mechanical defence responses of plants

A
  • thorns/ hairs to deter animals
  • leaves that curle or droop when touched
  • mimicry: some plants droop their leaves to mimic sick plant so animals won’t eat them. Some mimic butterfly eggs on their surface so actual butterflies will not lay eggs on them

Biology (16 decks)

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