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Biology GCSE > Infection and Response > Flashcards

Infection and Response Flashcards

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1
Q

How are infections caused?

A

Infections are caused whenever a foreign pathogen invades an organism.

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2
Q

What are viruses?

A

Viruses are tiny, non-living (do not contain cells) particles that can reproduce rapidly within the body.

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3
Q

What is bacteria?

A

Bacteria are small living cells that either damage cells directly or by producing toxins (poisons).

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4
Q

What is fungi?

A

Some fungi are single-celled organisms that have a body made up of hyphae (thread-like structures).

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5
Q

What are protists?

A

Protists are single-celled eukaryotic organisms (they have a nucleus).

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6
Q

How can a disease spread?

A
  • Water
  • Air
  • Direct contact
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7
Q

How can you prevent infectious spread?

A
  • Vaccination
  • Hygiene
  • Decrease vectors
  • Isolation
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8
Q

How does hygiene prevent infectious spread?

A

By being hygienic, we can destroy pathogens or wash them away so that they are not spread.
Using antibacterial products to clean surfaces, washing our hands and sneezing into a handkerchief are all hygienic measures to prevent the spread of infection.

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9
Q

How does a disease spread by water?

A

Some pathogens contaminate water supplies. Organisms drinking this contaminated water can be infected by pathogens.
Cholera is a disease spread in this way.

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10
Q

How does a disease spread by air?

A

Some pathogens are released into the air inside droplets when an organism coughs or sneezes. These droplets can then be inhaled (breathed in) by other organisms.

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11
Q

How does a disease spread by direct contact?

A

Some pathogens live on the surface of other organisms, such as the skin. If infected skin touches a surface, some of the pathogens can transfer from the infected skin to the surface.
The pathogen then spreads to other people who also touch that surface.

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12
Q

Describe how fungi infect:

A

The hyphae are able to grow and penetrate tissues, such as human skin or the surface of plants.
The hyphae produce spores that can spread to other plants and animals.

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13
Q

Describe how protists infect:

A

Many are parasites, meaning that they live on or inside other organisms.
They are often transferred to the host organism by a vector, such as an insect or mosquito.
They make us feel ill by damaging our tissues.

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14
Q

Describe how viruses infect:

A
  • To survive and replicate, they invade host cells (animals or plant cells).
  • The virus particle inserts its own DNA into the host cell’s DNA, which is then copied and used to make more viruses.
  • Once the new virus particles have been synthesised (made), they cause the cell to burst. This releases the new viruses to invade more cells.
  • This cell damage makes us feel ill.
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15
Q

Describe how bacteria infect:

A

Bacteria can reproduce rapidly in the appropriate conditions: warm, moist areas with a good supply of oxygen.
The toxins released by bacteria can damage cells and tissues, making us feel ill.

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16
Q

What diseases are caused by viruses?

A
  • tobacco mosaic virus (TMV)
  • measles
  • HIV
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17
Q

Describe TMV:

A

Tobacco mosaic virus (TMV) is a pathogen that affects plants, such as tomatoes.
The unique ‘mosaic’ pattern of the discolouration of the plant stunts the growth of the affected plant, because photosynthesis cannot take place.

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18
Q

Describe measles:

A

Measles is a virus that can be fatal if complications arise.
The measles virus is spread by breathing in (inhaling) droplets from sneezes and coughs.
Symptoms include a fever and red skin rash.

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19
Q

Describe HIV:

A

HIV is spread by sexual contact or the exchange of body fluids (e.g blood from sharing needles).
Initially, HIV causes a flu-like illness. However, unless antiretroviral drugs are used successfully, the HIV virus enters the lymph nodes and attacks the body’s own immune cells.

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20
Q

What are properties of a virus?

A
  • need a host cell to replicate
  • non living
  • smaller than 1 millimeter
  • acellular
  • rapid reproduction
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21
Q

What is AIDS?

A

AIDS is caused by HIV. It is the name given to the life-threatening infections that can happen when a person’s immune system has been badly damaged by HIV.

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22
Q

Describe gonorrhoea:

A

Gonorrhoea is a sexually transmitted disease.

Its symptoms include pain when urinating and a thick yellow or green discharge from the vagina or penis.

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23
Q

Describe salmonella:

A

If food has not been cooked properly or has been prepared in unhygienic conditions, then we may ingest (eat) Salmonella bacteria that cause food poisoning.
The bacteria release toxins (poisons), causing fever, stomach pain, vomiting and diarrhoea.

24
Q

Describe rose black spot:

A

Rose black spot can be spread in water or in the air (wind).
It causes purple or black spots on the leaves of rose plants.
Eventually, the leaves discolour and fall off. This makes it harder for plants to photosynthesise and plant growth slows.

25
Q

Describe malaria;

A

Malaria is spread by the female anopheles mosquito (a vector).
If a mosquito is carrying malaria, then it transfers the infection into a person’s bloodstream when it bites them.
Malaria leads to recurring and severe fevers, which can cause death.

26
Q

How many deaths were caused by malaria?

A

There were 212 million cases of Malaria in 2015 and it caused 429,000 deaths.

27
Q

How can you protect against gonorrhoea?

A

Barrier methods of contraception, such as condoms, can be used to stop the bacteria spreading from person to person.

28
Q

How can you protect against salmonella?

A

The bacteria release toxins (poisons), causing fever, stomach pain, vomiting and diarrhoea.

29
Q

How is skin a defence system for humans?

A

Skin is a waterproof barrier that pathogens cannot pass through.
Good bacteria live permanently on our skin, covering the surface and preventing pathogens from growing on our skin.

30
Q

How is mucus a defence system for humans?

A

Mucus is produced in the respiratory system and traps the particles and bacteria entering our airways.

31
Q

How is stomach acid a defence system for humans?

A

Glands in the stomach wall produce hydrochloric acid, which destroys any pathogens that enter the stomach.

32
Q

How are tears a defence system for humans?

A

Tears contain enzymes that destroy any pathogens that make contact with our eye.

33
Q

What is the immune system?

A

The immune system protects your child’s body from outside invaders. It is made up of different organs, cells, and proteins that work together.

34
Q

What are antibodies?

A

White blood cells recognise foreign antigens (proteins) on the surface of pathogens and produce protein molecules called antibodies.
Antibodies are specific to particular pathogens.

35
Q

What is phagocytosis?

A

A white blood cell finds the pathogen and engulfs it by changing shape.
The white blood cell ingests (absorbs) and digests the pathogen, destroying it.

36
Q

How does the immune system fight against toxins?

A

The immune system produces antitoxins, which neutralise the toxins released by bacteria and prevent them from causing harm.

37
Q

Describe the defence of the respiratory system:

A

Protected by a non-specific system.

  • Goblet cells in the lining of the respiratory system produces mucus which traps particles and bacteria entering our airways.
  • These airways have tiny hair-like structures on their surface called cilia which sweep the mucus upwards to the mouth.
38
Q

How do antibodies protect the body?

A

Antibodies, produced by white blood cells, have a complementary shape to the antigen and lock onto the antigen, effectively ‘tagging’ the pathogen. This causes the microorganisms to cluster, allowing other white blood cells to come and ingest (eat) them.

39
Q

What are antibodies?

A

Antigens are proteins found on the surface of cells.
White blood cells can recognise foreign antigens on the surface of pathogens and produce protein molecules called antibodies.

40
Q

What does vaccination do?

A
  • A vaccination injects a dead or inactive form of a pathogen into the blood.
  • White blood cells recognise that the antigens are foreign and produce antibodies against them.
  • Some of these white blood cells remain in the blood as memory cells so next time the same pathogen infects the vaccinated person, it will be destroyed by the immune system before it can cause illness.
41
Q

What is the use of memory cells?

A
  • Produce antibodies faster.

- Produce more antibodies, meaning that the antibody concentration remains in the blood for longer.

42
Q

What is herd immunity?

A

When we immunise a large proportion (or percentage) of the population, making it very hard for a pathogen to be spread.

43
Q

What is an antigen?

A

Proteins found on the surface of cells that antibodies bind to. They identify cells as ‘self’ or ‘foreign’.

44
Q

What are antibiotics?

A

Drugs developed to cure infections caused by bacteria. Some antibiotics work by destroying the cell wall of the bacteria so that they can’t replicate.
-Antibiotics do not destroy viruses because viruses stay inside host cells and are not living cells.

45
Q

How can we stop antibiotic resistance?

A
  • Doctors should only prescribe antibiotics if they are needed and not for minor infections or viral infections.
  • Patients should complete their course of antibiotics to ensure all bacteria are killed.
46
Q

How can bacteria become resistant to antibiotics?

A

Within populations of bacteria, some can mutate to be resistant to antibiotics.
The resistant bacteria can reproduce rapidly because their competition (the non-resistant bacteria) has been destroyed by the antibiotic.
When the resistant bacteria reproduce, they produce genetically-identical copies.

47
Q

Where did we get drugs from in the past vs now?

A

In the past, most drugs were extracted (taken from) from plants and microorganisms.
Nowadays, most drugs are synthesised (made) by chemists in the pharmaceutical industry using the ingredients of chemicals extracted from plants.

48
Q

What are the different drugs being produced today?

A
  • Painkillers
  • Antiviral drugs
  • Antibiotics
49
Q

What are painkillers?

A

Painkillers are used to relieve the pain caused by an infection.
They do not cure diseases or kill pathogens, but they do relieve the symptoms.

50
Q

What are antiviral drugs?

A

Viruses are found inside cells. This means it’s hard to destroy them without damaging the body’s cells and tissues.
Antiviral drugs are used to treat viral infections.

51
Q

What are antibiotics?

A

Scientists are always trialling new antibiotics for when new strains of resistant bacteria appear.

52
Q

What three main criteria are drugs tested on to ensure they are safe and effective for use?

A
  • Toxicity
  • Dose
  • Efficacy
53
Q

Describe preclinical testing:

A

Scientists carry out early stage testing on human cells and tissues grown in the laboratory (maybe animals).
Testing on animals is useful for working out how toxic (harmful) a drug is to cells.
In the UK, new medicines have to undergo tests on two different live mammals.
Many drugs fail at this stage if they damage cells or do not work.

54
Q

Describe clinical testing:

A

Clinical trials test drugs on healthy volunteers and patients to check that they are safe. They usually use low doses of the drug.
If a drug is found to be safe at low doses, there are more clinical trials to work out the optimum (best) dose for the drug.

55
Q

What are double blind trials?

A

In clinical trials, some patients are given a placebo (an alternative that does not contain any of the drug). Whether a patient gets the drug or the placebo is randomly chosen. Neither the patient nor the doctor knows who has received which.

Biology GCSE (2 decks)

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