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AQA GCSE BIOLOGY 9-1 > Topic 3 - Infection And Response > Flashcards

Topic 3 - Infection And Response Flashcards

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1
Q

What are pathogens?

A

Pathogens are microorganism a that enter the body and cause disease.

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2
Q

What do pathogens do?

A

They cause communicable diseases.

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3
Q

What can pathogens infect?

A

Both plants and animals.

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4
Q

What type of pathogens are there?

A

That can be:

  • Bacteria
  • Viruses
  • Protists
  • Fungi
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5
Q

What are bacteria?

A

Bacteria are VERY SMALL living cells which can rapidly reproduce inside your body.

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6
Q

What do bacteria do?

A

They can make you feel ill by producing toxins that damage your cells and tissues.

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7
Q

What are viruses?

A

Viruses are not cells. They are very small (much smaller than bacteria).

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8
Q

What do viruses do?

A

They reproduce rapidly inside your body.

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9
Q

What does a virus do inside a cell?

A
  • They live inside cells and replicate themselves using the cells’ machinery
  • The cell usually bursts, releasing all the new viruses.
  • This cell damage is what makes you feel ill
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10
Q

What are all protists?

A

All protists are EUKARYOTES. Most are single-celled.

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11
Q

What are parasites and what to they do?

A

Parasites are a type of protists. They live on or inside other organisms and can cause damage. They are often transferred by a vector, which doesn’ get the disease itself (e.g. an insect which carries the protist).

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12
Q

Fungi

A

Some are single-felled.
Some have bodies made up of hyphae (thread-like structures).
These hyphae can grow and penetrate human skin and the surface of plants.
These hyphae can produce spores, which can be spread to other plants and animals.

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13
Q

Ways pathogens can be spread

A

WATER: Pathogens can be picked up by drinking or bathing in dirty water. (e.g. Cholera)

AIR: Pathogens can be carried in the air and breathed in. (e.g. Influenza virus)

DIRECT CONTACT: Pathogens can be picked up by touching contaminated surfaces. (e.g. Athlete’s foot)

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14
Q

Viral Diseases: Measles

A
  • Measles is spread by droplets from an infected persons sneeze or cough.
  • People with measles develop a red skin rash and they show signs of a fever.
  • Measles can be very serious or even fatal if there are complications. It can sometimes lead to lung and brain infections.
  • Most people are vaccinated against measles when they are young.
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15
Q

Viral Diseases: HIV

A
  • HIV is spread by sexual contact or the exchange of bodily fluids.
  • Initially, HIV causes flu-like symptoms. Usually the person then doesn’t experience symptoms for several years. During that time, HIV can be controlled with antiviral drugs (they stop the virus replicating itself).
  • The virus attacks the immune cells
  • If the body’s immune system is badly damaged, it cannot cope with other infections or cancers. At this stage, the virus is known as late stage HIV infection, or AIDA.
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16
Q

Viral Diseases: Tobacco Mosaic Virus

A
  • TMV is a virus that affects many species of plants.
  • It causes a mosaic pattern on the leaves of the plants (parts of the leaves become discoloured).
  • The discolouration means that the plant can’t carry out photosynthesis as well, so the virus affects the growth.
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17
Q

Fungal Diseases: Rose Black Spot

A
  • Rose black spot is a fungus that causes purple or black spots to develop on the leaves of rose plants. The leaves can then turn yellow and drop off.
  • This means that less photosynthesis can happen, so the plant doesn’t grow very well.
  • It spreads through the environment in water or by the wind.
  • Gardeners treat the disease using fungicides and by stripping the plant of its affected leaves. Theses leaves need to be destroyed so that the fungus cannot spread to other rose plants.
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18
Q

Protist Diseases: Malaria

A
  • Part of the malarial protist’s life cycle takes place inside a mosquito.
  • The mosquitoes are vectors (they pick up the malarial protist when they feed on an infected animal).
  • Every time the mosquito feeds on another animal, it infects it by inserting the protist into the animal’s blood vessels.
  • Malaria causes repeating episodes of fever. It can be fatal.
  • People can be protected from mosquitoes using insecticides and mosquito nets.
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19
Q

Bacterial Diseases: Salmonella

A
  • Salmonella causes food poisoning
  • Infected people can suffer from fever, stomach cramps, vomiting and diarrhoea.
  • The symptoms are caused by toxins that the bacteria produces.
  • You can get Salmonella by eating food contaminated by the Salmonella bacteria, or by eating food that has been contaminated by being prepared in unhygienic conditions.
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20
Q

Bacterial Diseases: Gonorrhoea

A
  • Gonorrhoea is a sexually transmitted disease.
  • A person with gonorrhoea will get pain when seeing. Also, they will have thick yellow or green discharge from their genitals.
  • Originally, gonorrhoea was treated with penicillin, but no longer as strains of the bacteria have become resistant to it.
  • To prevent the spread of gonorrhoea, people can be treated with antibiotics and should use barrier methods of contraception.
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21
Q

How to prevent the spread of disease: Being Hygenic

A

Using simple hygiene methods can prevent the spread of disease.
E.g. Washing hands thoroughly before preparing food, or after sneezing.

22
Q

How to prevent the spread of disease: Destroying Vectors

A

By getting rid of the organisms that spread disease, you can prevent the disease from spreading. Vectors are insects that can be killed using insecticides or by destroying their habitat so that they can no longer breed.
E.g. The spread of malaria can be reduced by stopping mosquitoes from breeding.

23
Q

How to prevent the spread of disease: Isolating infected Individuals

A

If you isolate me one who has a communicable disease, it prevents them from passing it on to anyone else.

24
Q

How to prevent the spread of disease: Vaccination

A

Vaccination people and animals a against communicable diseases means that they can’t develop the infection and then pass it on to someone else.
E.g. In the UK most poultry is given a vaccination against Salmonella to control the spread of it.

25
Q

Defence System

A

The human body has many features to stop bad things entering the body:

  • The skin acts as a barrier to pathogens. It also secretes antimicrobial substances which kill pathogens.
  • Hairs and mucus in the nose trap parties that could contain pathogens.
  • The trachea and bronchi secrete much us to trap pathogens. They are also lined with cili which waft the mucus up to the back of the through the where it can be swallowed.
  • The stomach produces hydrochloric acid to kill pathogens that make it that far.
26
Q

The Immune System - Overview

A

If pathogens make it into the body them the immune system kicks in to destroy them. The most important part of the immune system is the WHITE BLOOD CELLS. They travel around in the blood and attack microbes when they come across them.

27
Q

The Immune System - Consumption

A

White blood cells can engulf foreign cells and digest them. This is called PHAGOCYTOSIS.

28
Q

The Immune System - Production of Antibodies

A

Every invading pathogen has unique antigens on its surface.
When lymphocytes come across a foreign antigen, they will start to produce antibodies to lock onto invading cells so that they can be found and destroyed by phagocytes. The antibodies produced are specific to that type of antigen.
Antibodies are then rapidly produced and carried around the body to find all similar bacteria or viruses.
If the person is infected with the same pathogen again, the lymphocytes will rapidly produce the antibodies to kill it and then the person will become naturally immune to that pathogen and won’t get ill.

29
Q

The Immune System - Production of Antitoxins

A

These counteract toxins produced by the invading bacteria.

30
Q

Vaccination - Protection from Future Infection

A
  • Vaccinations involve injecting small amounts of dead or inactive pathogens. These carry antigens, which cause your body to produce antibodies to attack them, even though the pathogen is harmless.
  • But if live pathogens of the same type later appear, the white blood cell can rapidly mass-produce antibodies to kill off the pathogen.
31
Q

Vaccination - Pros

A
  • Vaccines have helped control lots of communicable diseases that were once common in the UK.
  • Epidemics can be prevented if a large percentGe of the population is vaccinated. That way, even if the people who aren’t vaccinated are unlikely to catch the disease as there are fewer people to pass it on.
32
Q

Vaccination - Cons

A
  • Vaccinations don’t always work, sometimes they don’t give you immunity.
  • Sometime there can be a bad reaction to a vaccine (e.g. swelling, fever, seizures…). But bad reactions are very rare.
33
Q

Fighting Disease with Drugs - Symptom Relief

A
  • Painkillers are drugs that relieve pain. However, they don’t tackle the cause of the disease or kill, layhogens, they just help to reduce the symptoms.
  • Many other drugs do similar things.
34
Q

Fighting Disease with Drugs - Curing Problems

A
  • Antibodies kill/prevent the growth of the bacteria causing the problem without killing the body cells. different antibiotics kill different types of bacteria, so it is important to be treated with the right one.
  • Antibiotics DON’T DESTROY VIRUSES. Viruses reproduce using body cells, which makes it very difficult to develop drugs that destroy just the virus without killing the body’s cells.
  • The use of antibiotics has greatly reduced the number of deaths from communicable diseases caused by bacteria.
35
Q

Bacteria can become Resistant to Antibiotics

A
  • Bacteria can mutate, sometime causing them to be resistant to an antibiotic.
  • If infected, some of the bacteria may be resistant to antibiotics.
  • This means that when treated, only the non-resistant strains of bacteria will be killed.
  • The resistant bacteria will survive and reproduce, and the population of the resistant strain will increase. (NATURAL SELECTION)
  • This resistance strain could cause a serious infection that can’t be treated by antibiotics.
  • To slow down the rate of development of resistant strains, doctors must avoid over-prescribing antibiotics.
  • It is also important to finish the whole course of antibiotics and not stop when feeling better.
36
Q

Plant Drugs

A
  • Plants produce a variety of chemicals to defend themselves against pests and pathogens.
  • Some of these chemicals can be used as drugs to treat human diseases, or relieve symptoms.
  • Many current medicines were discovered by studying plants used in traditional cures.
  • Some drugs are extracted from microorganisms.
  • These days, drugs are made on a large scale pharmaceutical industry, although the process still might start with a chemical extracted from a plant.
37
Q

Drug Testing - Preclinical Stage

A

1)
Drugs are tested on human cells and tissues in a lab.
2)
-The drug is tested on live animals. this is to test EFFICACY (whether the drug works and produces the desired effect), to test its TOXICITY (how harmful it is, and to find the best DOSAGE (the concentration that should be given, and how often).
-Some think it is cruel to test on animals, but others believe that it is the safest way to make sure a drug isn’t dangerous before it is given to humans.

38
Q

Drug Testing - Clinical Stage (Part 1)

A
  • First the drug is tested in healthy volunteers. This is to make sure that it doesn’t have any HARMFUL SIDE EFFECTS when the body is working normally.
  • If the results are good, the drugs can be tested on ill people. The OPTIMUM DOSAGE is then found.
39
Q

Drug Testing - Clinical Stage (Part 2)

A

DOUBLE BLIND TRIAL: Some people are given a placebo (fake drug) and others are given the new one. Neither the doctors nor the patients know who has what u till all the results have been collected. This is so that the doctors monitoring the patients and analysing the results aren’t influenced by their knowledge.

40
Q

Drug Testing - Publication

A

The results of the drug testing aren’t published until they have bee peer reviewed. This helps to prevent false claims.

After the drug has been released, doctors still monitor patients to check for lo germ effects.

41
Q

Monoclonal Antibodies

A
  • Antibodies are produced by B-lymphocytes
  • Monoclonal antibodies are produced from lots of clones of a single white blood cell. This means all the antibodies are identical and will only target one specific antigen.
  • Lymphocytes don’t divide easily.
  • Tumour cells don’t produce antibodies but divide lots (grow very easily).
  • It is possible to fuse a mouse B-lymphocytes with a tumour cell to create a cell called hybridoma.
  • Hybridoma cells can be cloned to get lots of identical cells which all produce the same antibodies which can be collected and purified.
42
Q

Treating Diseases using Monoclonal Antibodies

A
  • Different cells have different antigens.
  • Cancer cells have antigens on their cell membranes that aren’t found on normal body cells. They’re called tumour markers.
  • In the lab, monoclonal antibodies which bind to the tumour markers can be made.
  • An anti-cancer drug can be attached to those monoclonal antibodies. This might be a radioactive substance, a toxic drug, or a chemical to storm cells growing and dividing.
  • The antibodies are given through a drip.
  • The antibodies target specific cells because they only bind to the tumour markers.
  • The drug kills the cancer cells but doesn’t kill any normal body cells near the tumour.
43
Q

Substance Research using Monoclonal Antibodies

A

Monoclonal antibodies are used to:

  • Bind hormones and other chemicals in blood to measure their levels.
  • Test blood samples in laboratories for certain pathogens.
  • Locate specific molecules on a cell or a cell or in a tissue: First monoclonal antibodies are made that will bind to the specific molecules you’re looking for. The antibodies are then bound to a fluorescent dye. If the molecules are present in the sample, then the monoclonal antibodies will attach them, and they can be detected using the dye.
44
Q

Monoclonal Antibodies: Pros & Cons

A

Pros:
-Other cancer treatments can affect normal body cells as well as killing cancer cells, whereas monoclonal antibodies target specific cells. This means the side effects are lower than for standard treatments.

Cons:
-They can cause fever, vomiting and low blood pressure. This means they are not used as often as scientists originally thought they would be.

45
Q

Why do plants need mineral ions?

A

Plants need mineral ions from the soil. If there aren’t enough, plants suffer from deficiency symptoms.

46
Q

What does a lack of nitrate do in plants?

A

Nitrates are needed to make PROTEINS and therefore for GROWTH.

A lack of nitrates causes STUNTED GROWTH.

47
Q

What does a lack of magnesium do in plants?

A

Magnesium ions are needed for making CHLOROPHYLL, which is needed for PHOTOSYNTHESIS.

Plants lacking in magnesium suffer from CHLOROSIS and have YELLOW LEAVES.

48
Q

Diseases Plants

A

Plants can be infected by VIRAL, BACTERIAL and FUNGAL pathogens. They can also be infested and damaged by insects. Common signs of disease are:

  • Stunted growth
  • Discolouration
  • Spots on leaves
  • Patches of decay
  • Abnormal growths
  • Malformed stems or leaves
49
Q

How to spot diseases

A
  • Looking up/comparing to pictures in a gardening manual or on a gardening website.
  • Taking the infected plant to a laboratory, where scientists can identify the pathogen.
  • Using testing kits that identify the pathogen using monoclonal antibodies.

Infestations of pests are easy to visually spot.

50
Q

Plant Defences: Physical

A
  • Most plants and stems have a waxy cuticle which provides a barrier to stop pathogens entering.
  • Plant cells are surrounded by cell walls made from cellulose. These also form a barrier against pathogens.
  • Plants have layers of dead cells around their stems. These also act as barriers.
51
Q

Plant Defences: Chemical

A
  • Some produce antibacterial chemicals which kill bacteria.

- Others produce poisons which can deter herbivores from eating them.

52
Q

Plant Defences: Mechanical

A
  • Some plants have adapted to have thorns and hairs which stop animals from touching and eating them.
  • Others have leaves the droop or curl when something touches them. This prevents them from being eaten by knocking insects off themselves and moving away from things.
  • Some can mimic other organisms. this tricks other organism into not eating them, or into becoming easy prey.

AQA GCSE BIOLOGY 9-1 (7 decks)

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