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Edexcel Biology Gcse > treating, curing and preventing diseases > Flashcards

treating, curing and preventing diseases Flashcards

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1
Q

agar plate

definition

A

A Petri dish that contains agar gel and usually some nutrients. Agar plates are used to culture (grow) bacteria and fungi in the lab.

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2
Q

agar gel

definition

A

A jelly-like substance that is derived from a type of seaweed and used in the lab as a medium on which to grow bacteria and fungi.

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3
Q

anaerobic

meaning

A

Without oxygen.

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4
Q

antibiotic

definition

A

Substance that controls the spread of bacteria in the body by killing them or stopping them reproducing.

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5
Q

antibiotic resistant

definition

A

The ability of bacteria to survive exposure to antibiotics. It is caused by mutations in their genes.

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6
Q

antibody

definition

A

A protein produced by the immune system in humans (and other animals) that attacks foreign organisms (antigens) that get into the body.

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7
Q

antigen

definition

A

A foreign organism that gets into the body and triggers an immune response.

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8
Q

antiseptic

definition

A

A substance that kills or stops the growth of germs which cause disease.

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9
Q

antiseptic techniques

meaning of the term

A

Name given to the laboratory procedures carried out to prevent the contamination of pure cultures of microorganisms.

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10
Q

What is a autoclave?

A

A strong heated container used to sterilise equipment.

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11
Q

bacteria

definition

A

Single-celled microorganisms, some of which are pathogenic in humans, animals and plants. Singular is bacterium

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12
Q

What is cilia?

A

Tiny hair-like projections from a cell that usually allow it to move a substance past the cell (for example, in the bronchioles in the lungs).

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13
Q

ciliated

definition

A

Cells with tiny hair-like structures on their surface are said to be ciliated.

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14
Q

What is conjunctivitis?

A

Irritation of the membrane that surrounds the eye.

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15
Q

What is a culture vial?

A

Small glass bottle with lid, often filled with a liquid in which bacteria grow.

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16
Q

What is a disease?

A

An illness affecting plants and animals.

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17
Q

enzyme

definition

A

A protein which catalyses or speeds up a chemical reaction.

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18
Q

What are goblet cells?

A

Cells in the lining of the airways that produce mucus to trap dust and pathogens.

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19
Q

herd immunity

definition

A

The protection given to a population against an outbreak of a specific disease when a very high percentage of the population have been vaccinated against it

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20
Q

immune system

definition

A

The body’s defence system against entry of any foreign body, including pathogens and agents such as pollen grains. The role of the immune system is to prevent disease.

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21
Q

What is immunisation?

A

The introduction of an inactive form of a disease into the human body that causes the immune system to produce antibodies against that disease.

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22
Q

immunity

definition

A

When a person’s body is not prone to a disease because they have a resistance to it.

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23
Q

What are lymphocytes?

A

White blood cells which attack pathogens by producing antibodies.

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24
Q

What are lysozymes?

A

Enzymes found in tears that destroy bacterial cells.

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25
Q

What is mucus?

A

Slimy white protein, which lines the respiratory tract and alimentary canal

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26
Q

mutation

definition

A

A random and spontaneous change in the structure of a gene, chromosome or number of chromosomes.

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27
Q

pathogen

definition

A

Microorganism that causes disease.

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28
Q

What is a petri dish?

A

A clear glass or plastic dish, used to grow living cells from organisms so they can be studied.

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29
Q

What are phagocytes?

A

Cells, such as white blood cells, that engulf and absorb waste material, harmful microorganisms, or other foreign bodies in the bloodstream and tissues.

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30
Q

What is protein synthesis?

A

The production of proteins from amino acids, which happens in the ribosomes of the cell.

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31
Q

toxin

definition

A

A type of natural poison produced by an organism, often as a form of protection.

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32
Q

trachea

definition

A

The windpipe, the tube that leads from the mouth towards the lungs.

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33
Q

vaccine

definition

A

Substances containing disabled antigens of a particular disease, usually administered via injection. Vaccines stimulate the body to produce antibodies to provide immunity against that disease.

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34
Q

white blood cell

definition

A

A type of cell found in blood that defends against infection.

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35
Q

zone of inhibition

definition

A

The area around an antibiotic or antiseptic on agar where bacterial growth is not visible. The size of the zone depends on how effective the antibiotic or antiseptic is.

36
Q

Defence against infection
Human body
(overview)

A

The body is constantly defending against attacks from pathogens. The first line of defence against infection stops the pathogens from entering your body. These first lines are general defences, and are not specific to fight against certain types of pathogen. We call this non-specific, and they can be physical or chemical barriers.

37
Q

Defence against infection
Human body
List Physical barriers against infection

A
  • Skin
  • Nose
  • Mucus and ciliated cells
38
Q

Defence against infection
Human body
Physical barriers against infection

Skin

A

The skin covers almost all parts of your body to prevent infection from pathogens. If it is cut or grazed it immediately begins to heal itself, often by forming a scab, which prevents infection as the skin acts as a physical barrier. Parts of the body that do not have skin have developed other ways to prevent infection. For example, the eyes produce tears which contain enzymes. These enzymes are chemical barriers.

39
Q

Defence against infection
Human body
Physical barriers against infection

Nose

A

The nose has internal hairs, which act as a physical barrier to infection. Cells in the nose produce mucus. This traps pathogens before they can enter the lungs. When the nose is blown, mucus is removed and any pathogens are trapped within it.

40
Q

Defence against infection
Human body
Physical barriers against infection

Mucus and ciliated cells

A

The trachea runs from the nose towards the lungs. The cells that line the trachea also have hairs called cilia, which are much smaller than those in the nose. These are called ciliated cells. The ciliated cells waft their hairs in a motion like a Mexican wave at a football match and move mucus and pathogens upwards towards the throat where it is swallowed into your stomach. Other cells called goblet cells create the mucus in order to trap pathogens. The production of mucus in your airways is a physical barrier.

41
Q

Features of skin

cross section of skin

A
  • Hair shaft
  • Capillaries
  • Epidermis
  • Dermis
  • Vein
  • Artery
  • Subcutaneous tissue
42
Q

Defence against infection
Human body

List Chemical barriers against infection

A
  • Stomach acid

- Lysozymes

43
Q

Defence against infection
Human body
Chemical barriers against infection

Stomach acid

A

The hydrochloric acid in our stomachs does not break down food. It is part of the body’s non-specific first line of defence. It is hydrochloric acid and while it does us no harm, it is strong enough to kill any pathogens that have been caught in mucus in the airways or consumed in food or water. Stomach acid is a chemical barrier against infection.

44
Q

Defence against infection
Human body
Chemical barriers against infection

Lysozymes

A

To stop eye infections we have evolved chemicals within our tears called lysozymes. These are enzymes that destroy bacterial cells by breaking down their cell walls. Lysozymes are found in saliva, breast milk and mucus, as well as in tears. Lysozymes are chemicals so, like stomach acid, they are a form of chemical defence against infection.

45
Q

The immune systems defences against disease

how do you catch a communicable disease?

A

You can catch a communicable disease when you are exposed to a pathogen. There are many ways in which this can happen, but some include touching an infected person, drinking dirty water or breathing in an airborne pathogen.

46
Q

The immune systems defences against disease

overview

A

If pathogens pass the non-specific first line of defence they will cause an infection. However, the body has a second line of defence to stop or minimise this infection. This is called the immune system. As a part of this there are two types of white blood cell called phagocytes and lymphocytes.

47
Q

The immune systems defences against disease

Phagocytes

A

Phagocytes are white blood cells. They are attracted to pathogens. They surround them in the blood, bind to them and engulf them.

The phagocytes’ membrane surrounds the pathogen and the enzymes found inside the cell, then break down the pathogen in order to destroy it. As phagocytes do this to all pathogens that they encounter, we call them ‘non-specific’.

48
Q

The immune systems defences against disease

Lymphocytes

A

Lymphocytes are another type of white blood cell. They recognise proteins on the surface of pathogens called antigens. Lymphocytes detect that both the proteins and pathogens are foreign, not naturally occurring within your body and produce antibodies. This can take a few days, during which time you may feel ill. The antibodies created by the lymphocytes cause pathogens to stick together, and make it easier for phagocytes to engulf them.

49
Q

The immune systems defences against disease

memory lymphocyte

A

A specific type of lymphocyte called a memory lymphocyte can ‘remember’ the antigens from an infection by a previous pathogen. A second exposure to it will result in a much faster immune response. Antibodies will be produced much faster, which often stops us becoming ill again. There are hundreds of common colds caused by different viruses. It is very unlikely you will become infected by the same virus because memory lymphocytes exist to fight the infection immediately. This response to a known antigen is called the secondary response and it is much quicker than the response to an antigen for the first time.

50
Q

The immune systems defences against disease

vaccines
immune systems response during primary and secondary infections.
anibodies

A

During the primary infection the antibodies slowly increase, peak at around ten days and then gradually decrease. A second exposure to the same pathogen causes the white blood cells to respond quickly in order to produce lots of the relevant antibodies, which prevents infection.

51
Q

The immune systems defences against disease

Toxins and antitoxins

A

Some pathogens produce toxins which make you feel ill. Lymphocytes can also produce antitoxins to neutralise these toxins. Both the antibodies and antitoxins are highly specific to the antigen on the pathogen, thus the lymphocytes that produce them are called ‘specific’.

52
Q

Immunisations

A

Pathogens are microbes that cause diseases. Immunisations allow an inactive form of the disease causing pathogen to be introduced into the body, which contain a specific antigen. This causes the immune system, specifically the white blood cells, to produce complementary antibodies, which target and attach to the antigen.

53
Q

Immunisations

step by step

A

1) Syringe injects an altered or weakened form of the pathogen.
2) White blood cells release complementary antibodies to the specific antigen.
3) They attach and clump pathogens together.
4) White blood cells engulf the pathogens. Phagocytosis occurs.

54
Q

Herd immunity

A

Following an immunisation, a person can become immune to the specific disease. This immunity gives protection against illness in an individual. When the majority of the population are immunised against serious diseases, this means that even those people who have not been immunised will still be protected because they are less likely to come into contact with an infected person. This type of immunity is herd immunity.

55
Q

There are three recognised scenarios in relation to herd immunity, described below.

A

1) The majority of the population are not immunised against a specific disease, however, a few people are ill and contagious. This can develop easily into a mass infection because the majority of the population aren’t immunised.
2) Most of the population are not immunised against the specific disease but are well, some are immunised and healthy, and a few are not immunised, but ill and contagious. Mass infection can result again, but a small number of immunised individuals remain healthy and some that are not immunised will also be healthy.
3) The majority of the population are immunised and healthy against a specific disease, a few are not immunised but well. A few are not immunised against the disease, and they are ill and contagious. The result is that the majority are protected due to the high level of immunisation. A few individuals will still become ill, but the large number of immunised individuals gives protection.

56
Q

Herd immunity

What happens if the number of people immunised against a specific disease drops in a population?

A

If the number of people immunised against a specific disease drops in a population, it leaves the rest of the population at risk of mass infection, as they are more likely to come across people who are infected and contagious. This increases the number of infections, as well as the number of people who could die from a specific infectious disease.

57
Q

Antibiotics

A

Antibiotics are substances that slow down or stop the growth of bacteria. They are commonly prescribed medicines, examples include penicillin and amoxicillin. These can be taken to cure the diseases by killing the pathogens, but only cure bacterial diseases and not viral ones.

58
Q

Antibiotics

Penicillin

A

Penicillin was the first antibiotic discovered in 1928 by Alexander Fleming. He noticed that some bacteria he had left in a Petri dish had been killed by the naturally occurring Penicilliummould.

59
Q

How do antibiotics work?

A

Antibiotics damage the bacterial cells by inhibiting their cellular processes, but do not damage the host cells. They have the ability to cure some bacterial diseases that would have previously killed many people. Since their introduction, they have had a large influence on the world’s health and death rate.

Different bacteria cause different diseases. One antibiotic may only work against one type of bacteria, or a few types. This means that a range of different antibiotics is needed for the treatment of the whole range of bacterial diseases.

60
Q

Antibiotics

Viral diseases

A

Viral diseases cannot be cured by antibiotics, as they reproduce inside the host cells. It is very difficult to develop antiviral drugs, as they might damage the host cell whist killing the virus. Antiviral drugs only slow down viral development, and viruses change their antigens quickly which means new drugs have to be generated regularly.

61
Q

Viruses in a cell

step by step

A

1) A virus enters a cell.
2) Substances in the cell begin to to strip of the virus’ outer protein coat.
3) The nucleic acid in the centre of the virus is released.
4) the nucleic acid gets into the cell’s chemical manufacturing system.
5) The cell ignores it’s own chemical needs and switches to making new viruses
6) The cell is sometimes destroyed in the process. Many of the new viruses are released to infect other cells.

62
Q

Antibiotic resistance

overview

A

Since Penicillin was discovered in 1928, the use of antibiotics for the treatment of diseases has increased exponentially. Antibiotics are being overused in many ways in our world today.

63
Q

Antibiotic resistance
Problems with antibiotics

  • Commonly prescribed antibiotics are becoming less effective due to a number of reasons:
  • What does this lead to
A
  • over use of antibiotics
  • failing to complete the fully prescribed course by a doctor
  • use of antibiotics in farming

These can lead to the effectiveness of antibiotics being reduced, and the incidence of antibiotic resistance increasing. These bacteria are commonly known as superbugs.

64
Q

Antibiotic resistance

Over use

A

People feel unwell and when going to the doctors, they expect antibiotics to be prescribed. If patients have viral infections, such as the common cold and not a bacterial one, the antibiotics are ineffective and unnecessary.

65
Q

Antibiotic resistance

Failing to complete the course

A

Patients should always fully complete the prescribed course of antibiotics, every time they are taken. This ensures all bacteria are killed, and so none survive which can subsequently mutate and produce resistant strains. Some patients begin to feel well after a few days of taking the medicine, and stop taking them. This is potentially very harmful, as random mutations can occur which can lead to antibiotic resistance. The resistant bacteria reproduce quickly, and the resistance spreads.

66
Q

Antibiotic resistance

Agricultural use

A

Previously, antibiotics were regularly used in farming, and these can be used to prevent disease, keep the animals well and allow them to grow quickly. The high use in agriculture may have a cost, as it could lead to spread of antibiotic resistance from animals into human hosts. Legal controls are now in place to try and reduce the use of antibiotics in this way.

67
Q

Antibiotic resistance

Ways to reduce antibiotic resistance

A
  • Only take when necessary.
  • Treat specific bacteria with specific antibiotics.
  • High hospital hygiene levels, including regular hand washing by staff and visitors.
  • Patients, who are infected with antibiotic resistant strains of bacteria, should be isolated from other patients.
68
Q

Antibiotic resistance

The future

A

The development of new antibiotics has slowed down as it becomes difficult to find new versions to tackle different bacterial infections. Some limited success with new antibiotic search has occurred recently. People are concerned that in the near future, some bacteria will be resistant to all known antibiotics.

69
Q

Bacterial growth in cultures

How often can bacteria replicate?
How?
What does this depend on?

A

Bacteria can replicate approximately every 20 minutes by binary fission, which is a simple form of cell division. This level of replication will depend on the availability of nutrients and other suitable conditions such as temperature.

70
Q

Bacterial growth in cultures

There are many ways to culture bacteria, and these include:

A
  • nutrient broth solution in a culture vial

- colonies on an agar plate

71
Q

Bacterial growth in cultures

Function of nutrient broth solution or culture medium

A

Nutrient broth solution or culture medium, allows a liquid or gel to provide all the nutrients needed for bacteria to grow successfully. These must include: carbohydrates for energy, nitrogen for protein synthesis, plus other minerals.

72
Q

Bacterial growth in cultures

Agar plates

A

Agar plates are created by pouring hot molten agar into sterile Petri dishes, which are then allowed to set. Bacteria can be streaked onto the plates using a loop, and allowed to form individual colonies of the specific bacterium. Alternatively, bacteria can be spread all over the agar plate to form a lawn of bacterial growth, rather than individual colonies.

73
Q

Bacterial growth in cultures

Sterilisation of equipment

A

Nutrient broth solutions, culture vials, agar solution and Petri dishes are all sterilised to stop any other microorganisms growing on or in them. This is often done in an autoclave. These are strong containers, a little like ovens, which use high temperatures and pressures to kill microorganisms.

74
Q

Bacterial growth in cultures

Uncontaminated cultures

A

If a specific bacterium is going to be cultured or grown, other contaminating bacteria would compete for nutrients in the broth or agar. Plus some bacteria could be harmful (such as pathogens) and would complicate the results of experiments when testing the efficiency of antibiotics or other anti-microbial compounds.

75
Q

Bacterial growth in cultures
Aseptic technique

To avoid contaminating cultures a special set of
processes are used that are called aseptic technique. This includes:

A
  • killing all microorganisms on equipment such as inoculating loops by flaming equipment in a Bunsen burner or dipping them in alcohol
  • keeping all lids on equipment when not in use
  • wearing gloves, eye goggles, lab coats or other protective equipment
76
Q

Bacterial growth in cultures
Aseptic technique

Why?

A

This avoids contaminating cultures that should already be sterile. The growth medium (broth solutions and agar) will be sterile after autoclaving. The containers (Petri dishes and culture vials) will also be sterile after autoclaving.

77
Q

How to calculate the number of bacteria in a population

eg. The mean division time for bacteria population A is 20 minutes. The starting bacteria population of A is 1. Calculate how many bacteria will be present after 6 hours.

A

In order to answer this, you can split the calculations into two sections.

1) Calculate how many times the bacteria divide in 6 hours.
Bacteria divide every 20 minutes, and will divide three times every hour (60 ÷ 20 = 3)
3 × 6 = 18

2) Calculate the number of bacteria in the population.

Every time the bacteria reproduce, the number doubles. You can use an equation to calculate this.

Bacteria at the end of the growth period = bacteria at the beginning × 2number of divisions of the growth period

Number of bacteria at the beginning = 1

Number of divisions = 18

Using the above equation: 1 × 218 = 1 × 262,144 = 262,144 bacteria

For a higher mark, you could express answers in standard form.

For example, the above answer of 262,144 bacteria can also be written as 2.62 × 105 bacteria.

78
Q

How to calculate the number of bacteria in a population
Question

The mean division time for a bacterial population is 30 minutes. Calculate how many bacteria will be present after 8 hours, when starting with 1 bacterium.

A

2 divisions per hour. 2 × 8 = 16 total divisions, therefore 1 × 216 = 1 × 65,536 which is 65,536 bacteria or 6.55 × 104 bacteria (standard form).

79
Q

How to calculate the number of bacteria in a population
Question

The mean division time for bacteria population C is 20 minutes. Calculate how many bacteria will be present after 2 hours, when starting with 10 bacteria.

A

3 divisions per hour. 3 × 2 = 6 total divisions, therefore 10 × 26 = 10 × 64 which is 640 bacteria or 6.4 × 102 bacteria (standard form).

80
Q

What type of cell engulfs pathogens?

A

Phagocytes

81
Q

Who discovered the first antibiotic?

A

Alexander Fleming

Penicillin

82
Q

Give an example of a non-specific defence against disease

A

Antibodies

83
Q

Give an example of a non-specific defence against

infection

A

Skin

84
Q

What do goblet cells produce?

A

Mucus

85
Q

What do phagocytes produce to destroy pathogens?

A

Enzymes

Edexcel Biology Gcse (36 decks)

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