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Biology Aqa Science > Topic 3 Infection and Response > Flashcards

Topic 3 Infection and Response Flashcards

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1
Q

What are Pathogens

A

Pathogens are microorganisms that enter the body and cause infectious disease. Both plants and animals can be affected by pathogens.

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2
Q

Name the four different types of pathogens

A

Bacteria, Viruses, Protists and Fungi

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3
Q

What are Bacteria and how do they make you feel ill

A

Tiny living cells that reproduce inside the body very rapidly (In Ideal conditions dividing every 20min) producing toxins that damage cells and tissues which in turn makes you feel ill.

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4
Q

What are Viruses

A

Viruses are not cells. They are tiny particles capable of infecting living organisms. They cannot reproduce by themselves and can only reproduce inside a host cell.

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5
Q

Describe the process of a virus replicating inside a human cell

A

1 - The virus invades the body cell
2 - The virus then replicates itself thousands of times causing damage to the cell
3 - The cell will usually burst open causing all the new viruses to be released.
PROCESS IS CALLED LYSE

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6
Q

What are protists

A

Protists are eukaryotic microorganisms and are usually single celled organisms (They have a nucleus). Some protists are parasites that live in or on another organism that can cause damage
Often transferred to the organism by a vector (which doesn’t get the disease itself) (Insect that carries the protist) Example: Malaria (mosquito’s are the vector)

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7
Q

Give an example of different types of bacteria

A

Salmonella - Causes food poisoning

Gonorrhoea - STD

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8
Q

Give an example of a type of Virus

A

HIV - Infects and destroys the immune cells
Tobacco Mosaic virus - (Plant pathogen) attacks chloroplasts changing leaves colours form green to yellow/white reducing the plants ability to photosynthesis

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9
Q

What are fungi

A

Some fungi are single celled.
Some have a body that is made up of hyphae (thread like structures). These hyphae can grow and penetrate human skin and surfaces of plants, causing diseases.
Hyphae can produce spores which can be spread to other plants and animals

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10
Q

Name and describe the 3 ways in which pathogens can be spread

A

Water - Drinking or bathing in dirty water (cholera bacteria spread by drinking dirty water)

Air - Carried in the air and can be breathed in (Influenza spread through coughing or sneezing so virus droplets are breathed in)

Direct Contact - Spread through touching contaminated surfaces (Athletes foot is a fungus most commonly spread by touching same things as infect person e.g. shower floor, towel)

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11
Q

Describe the Measles viral disease and its characteristics

A
  • Spread through droplets from a infected person sneeze or cough
  • Symptoms include Red skin Rash and a High Fever
  • If complications arise can be very serious leading to pneumonia or encephalitis (Brain infection)
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12
Q

Describe the HIV viral disease and its characteristics

A
  • Spread through sexual contact or sharing of bodily fluids such as blood
  • Initially causes flu like symptoms for a few weeks, usually the person does not experience any symptoms for several years.
  • HIV can be controlled with antiviral drugs, these stop the virus replicating in the body.
  • The virus attacks the immune cells, if this is damaged the body can’t cope with other infections or cancers.
  • At this stage, the virus is known as late stage HIV or AIDS.
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13
Q

Describe the Tobacco Mosaic virus and its characteristics

A
  • Virus that affects many species of plants.
  • Causes mosaic pattern on leaves, causing discolouration, meaning the plant can’t carry out photosynthesis as well.
  • The virus affects growth
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14
Q

What is Rose Black spot

A
  • Rose Black spot is a fungus that causes purple black spots to appear on the leaves of a plant which in turn causes leaves to turn yellow and drop off
  • This hinders the plants ability to photosynthesise stunting plant growth
  • Spread through environment e.g wind, water
  • Treatment can be fungicides or removing infected leaves and destroying them
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15
Q

What is Malaria

A
  • Protist disease
  • Malaria is caused by a protist, part of the malarial parasites life cycle takes place inside the mosquito.
  • The mosquitoes are VECTORS, they pick up the protist when they feed on an infected animal.
  • Subsequently passing it on to other animals every time it feeds, by inserting it into the blood stream
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16
Q

How can the spread of malaria be reduced

A
  • Mosquitos can breed on standing water so breeding can be prevented by removing these water sources.
  • People can also protect themselves from mosquito bites by using insect repellent or sleeping under mosquito nets in turn stopping the spread of the disease
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17
Q

What is salmonella describe the symptoms and control measures

A
  • Bacteria causes food poisoning
  • Symptoms include stomach cramps, vomiting and diarrhoea (bacteria produce toxins which make us feel ill)
  • you can get salmonella by eating food that has been infected with the salmonella bacteria
  • Vaccinations are given to poultry in order to control the spread of disease through human consumption.
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18
Q

What is Gonorrhoea describe the symptoms and control measures

A
  • STD passed on by sexual contact
  • Symptoms include pain urinating and a thick yellow discharge form genitals
  • Treated with antibiotics namely penicillin although certain strains of bacteria have become increasingly resistant to it
  • Prevention can include barrier methods of contraception such as condoms.
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19
Q

How can we prevent the spread of disease

A
  • Being hygienic - Simple hygiene methods can help reduce the spread of disease e.g. washing hands thoroughly before food prep
  • Destroying vectors - Insects and organisms that carry disease can be killed using insecticides or destroying the habitat so they can no longer breed
  • Isolating infected individuals - isolating someone infected with a communicable disease prevents the disease from further spreading to other individuals
  • Vaccination - Vaccination means that individuals cant develop the infection and pass it on to other people
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20
Q

What are non specific defences

A

Features which the human body has to prevent pathogens entering

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21
Q

Name the body’s non specific defences and explain how they help prevent the entry of pathogens

A

Skin - acts as a barrier for pathogen entry and also secretes anti microbial substances which kill pathogens

Hair/Mucus - in the nose help trap particles that could contain pathogens

Trachea and Bronchus - secrete mucus to trap pathogens. Lined with cilia which waft the mucus containing the pathogens up to the back of the throat where it can be swallowed

Stomach acid - Hydrochloric acid (PH1) within the stomach destroys most pathogens that make it that far

22
Q

Name and explain three ways in which White Blood cells defend against pathogens

A

Consuming them - They can engulf foreign cells and digest them in a process known as Phagocytosis

Producing Anti toxins - Which counteract toxins produced by the invading bacteria

Producing Antibodies/B-lymphocytes - Every invading pathogen has a unique code antigens on its surface. White blood cells produce antibodies specific to the foreign antigen which lock onto them so they can be found and destroyed by other white blood cells.

23
Q

explain why someone who has previously suffered from the measles virus are unlikely to get ill from the virus again

A

Upon the initial illness the body would have produced antibodies specific to the antigens of the measles pathogen to help identify and destroy the virus. This means that if the body was exposed to the measles pathogen again it will already have the antibodies specific to the antigen therefore the body will be able to defend against infection and produce antibodies to rapidly kill the virus.

24
Q

What are Vaccinations

A

A vaccination is the introduction of a dead or inactive pathogen into the body carrying a specific antigen. This induces the white blood cells to produce an antibody specifically for the antigen which attach to and attack it. This means if a person is exposed to the same pathogen at a later date the body can produce the antibodies to destroy it and the vaccinated person is ow immune to that pathogen.

25
Q

What are the pros of vaccination

A
  • Vaccines have helped to control lots of infectious disease that were once common in the uk e.g. measles, mumps, rubella polio.
  • Big outbreaks of disease called epidemics can be prevented through large scale vaccination. In turn even people who aren’t vaccinated are unlikely to catch the disease because fewer people are able to pass it on.
26
Q

What are the cons of vaccination

A
  • Vaccines don’t always work or give you immunity

- Bad reactions to vaccines are a possibility

27
Q

What are pain killers

A
  • Drugs that relieve pain by reducing the symptoms without tackling the root cause of the disease
28
Q

What are antibiotics

A
  • Antibiotics are drugs that kill or prevent the growth of bacteria.
  • They don’t destroy viruses (viruses reproduce use your own body cell so killing the virus without killing the host cell is very difficult
29
Q

Give an example of an antibiotic

A
  • Penicillin (used in first world war to treat soldiers with pneumonia a bacterial infection of the lungs)
30
Q

Why is it important to be treated with the right antibiotic for a particular infection

A

Because certain bacteria may be resistant to the wrong antibiotics in which case the resistant strain will grow and reproduce increasing their population

31
Q

Why is it important not to overuse antibiotics

A

As this will slow down the development of resistant strains.

32
Q

Who discovered penicillin and how a was it discovered

A
  • Alexander Fleming
  • He noticed a Green mould that was killing bacteria he was growing in Petri dishes in his lab. The substance being released by the mould was penicillin
33
Q

What are the origins of drugs

A

A large amount of drugs are derived from studying plants and the chemicals secreted by them.

34
Q

What plant is asprin derived from

A
  • Asprin is a pain killer used to lower fever and is derived from the plant WILLOW
35
Q

What is the drug Digitalis and what plant was it developed from

A
  • Digitalis is used to to treat Heart conditions

- It was developed form a chemical found in the plant Foxglove

36
Q

What are the three main stages of drug testing

A
  1. Preclinical Testing on Cells and Tissues - Drugs are tested on human cells and tissues in a lab. (when testing drugs that affect whole body systems whole body systems need to be used not just body cells and tissue e.g. blood pressure drugs must be tested on an intact circulatory system
  2. Preclinical trials on Live animals - The next step is to test the drug on a live animal. This is to test the efficacy (does the drug work and produce the desired effect your looking for). It also tests the toxicity of the drug to find out the best dosage which should be given (concentration that should be given and how often it should be taken)
  3. Clinical trials - tested on humans. Firstly low dose on healthy volunteers to ensure there’s no harmful side effects. Then tested on ill people to find optimum dose.
37
Q

What is Clinical Trials

A
  • Clinical trails are the stage of drug testing directly after pre clinical trails.
  • At this stage the drugs are to be tested on humans
  • Drugs are firstly tested on healthy volunteers to ensure it doesn’t have any harmful side effects on a healthy working body.
  • Low dose at start of the trial which is gradually increased.
  • If the results are good the drug can then be tested on people suffering from the illness. The optimum dose is found (this is the dose the drug is most effective at with the least side effects.
38
Q

What is a Placebo

A
  • A substance that’s like the drug being tested but doesn’t actually do anything
  • It allows the doctor to see the actual difference a drug is making.
39
Q

Briefly describe what is involved in a double blind trial

A
  • Its a clinical trial where the doctor nor the patient actually know who has been given the drug or the placebo until the results of the trail have been gathered.
40
Q

What two things are fused together to make a hybridoma

A

A mouse b-lymphocyte + Tumor cell

41
Q

What are monoclonal antibodies

A
  • Monoclonal antibodies are antibodies made from lots of clones of a single white blood cell (lymphocyte)
  • This means this means all the antibodies will be identical and target the same specific antigen
42
Q

What happens in monoclonal antibody production after the hybridoma cell has been made

A
  • Hybridoma cells are cloned to get multiple amounts of identical antibodies, they are then collected and can be purified for future use.
43
Q

What are antibodies

A
  • Y-shaped proteins that are produced by the immune system to help stop intruders from harming the body
44
Q

What happens to plants lacking in magnesium ions

A
  • Magnesium ions are needed for making chlorophyll an essential element of photosynthesis. Lack of magnesium causes chlorosis (yellowing of leaves)
45
Q

What happens to plants lacking in nitrate ions

A
  • Nitrates are needed to make proteins and therefore for growth
  • Lack of Nitrates causes stunted growth
46
Q

What are the 3 defences plants have against pests and pathogens

A

Physical defences:

  • Waxy cuticle to stop pathogens entering
  • Cell walls made from cellulose forming a physical barrier for pathogens that get past waxy cuticle
  • Layer of Dead cells e.g bark to stop pathogens entering

Chemical Defences:

  • Produce antibacterial chemicals which kill bacteria
  • Produce poisons which deter herbivores e.g. foxglove, night shade

Mechanical Defences:

  • Adaptations like thorns to stop animals touching or eating them
  • Mimic other organisms to trick animals into not eating them e.g. passion flower has yellow spots which look like butterfly eggs to stop other butterflies laying eggs on their leaves
47
Q

Describe the difference between how drugs are made now and how they were traditionally made

A

Traditionally made from extracting chemicals from plants where as nowadays they are synthesised on a large scale by chemist’s in labs

48
Q

Name three signs of plant disease

A

Stunted growth
Discoloration
Patches of decay
Malformed stems/leaved

49
Q

How can rose black spot be spread

A

Fungal infection carried in the wind or carried by water

50
Q

How should a plant with rose black spot be treated

A
  1. Treated with a fungacide solution

2. Strip the plant of its affected leaves and destroy them

Biology Aqa Science (15 decks)

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