B3 - Infection & Response

Question 1

What is a pathogen?

Answer 1

A microorganism that causes disease

Question 2

What type of diseases do pathogens cause?

Answer 2

Communicable diseases (infectious, easily spread)
They infect both plants and animals

Question 3

What are bacteria? How do they make you feel ill?

Answer 3

Very small living cells (around 1/ 100 of your body cells), which reproduce rapidly.
When the reproduce, they produce toxins that damage cells and tissues

Question 4

A bacterium is about 1/100th the size of your normal body cell. So how big is a virus?

Answer 4

Around 1/100th of a bacterium. VIRUSES ARE NOT CELLS!

Question 5

How do viruses reproduce?

Answer 5

They live inside cells and replicate themselves using the cells’ machinery to produce copies of themselves. Eventually the cell will burst, releasing all new viruses and making you feel ill too

Question 6

What are protists?

Answer 6

Single-celled eukaryotes.
Some are parasites, which live on or inside another organism and can cause them damage. They’re often transferred to the organism by a vector, which doesn’t get the disease itself (e.g. an insect that carries the protist)

Question 7

Fungi come in different shapes, some are single celled, but others havea body made from what?

Answer 7

Hyphae - a thread like structure. These can grow and penetrate human skin and the surface of plants, causing diseases.
The hyphae can produce spores, which can be spread to other plants & animals

Question 8

What can hyphae produce?

Answer 8

Spores, as some fungi are made up from hyphae, a thread like substance

Question 9

What are the 3 main ways which pathogens spread?

Answer 9

1) Water (drinking/ bathing in dirty water. Cholera is an example)
2) Air (pathogens can be carried by the air. Some airborne pathogens are carried by droplets produced from coughing or sneezing. The influenza virus that causes flu is a example)
3) Direct contact (by touching contaminated surfaces, including skin, pathogens can be picked up. Athletes foot (a fungal infection making the skin itch and flak off) is an example of this, as it can be spread by touching the same thing the infected person touched like shower floors and towels)

Question 10

What virus causes the flu?

Answer 10

Influenza virus

Question 11

What examples of diseases do you need to know from:

a) Viral
b) Fungal
c) Protist
d) Bacterial

Answer 11

a) Measles, HIV, Tobacco Mosaic Virus (TMV)
b) Rose black spot (don’t need to know athletes foot, but it is fungal)
c) Malaria
d) Salmonella, Gonorrhoea

Question 12

Talk about measles

What type of disease, how spread, symptoms, dangers, cure

Answer 12

It is a viral disease spread by dropletes from an infected person’s sneeze/ cough
People develop a red skin rash & they’ll show signs of a fever (high temperature)
It can be very serious & fatal if there are complications. Measles can sometimes lead to pneumonia (lung infection), or a brain infection called encephalitis
Most people are vaccinated against it when they are young, so they are immune to it

Question 13

Talk about HIV

What type of disease, how spread, symptoms, dangers, cure

Answer 13

It is a virus spread by sexual contact, or by exchanging bodily fluids such as blood (e.g. from sharing needles when taking drugs)
Initially, it causes flu-like symptoms for a few weeks. Usually, then they don’t experience more symptoms for a few years. During this time, HIV can be controlled with antiretroviral (anti-retro-viral ya spelling loser) which stops the virus replicating in the body
The virus attacks immune cells, making it difficult for your body to fight any disease
If a body’s immune system is badly damaged, it can’t cope with other infections or cancers, at this stage, the virus is known as “late stage HIV infection” of AIDS

Question 14

Talk about Tobacco Mosaic Virus

What type of disease, how spread, symptoms, dangers, cure

Answer 14

It is a virus that affects many plant species, such as tomatoes
It causes a mosaic pattern on the leaves of the plants - parts of the leaves become discoloured
The discoloration means plants can’t conduct photosynthesis as well, so the virus affects growth. Photosynthesis is important for plant growth because it produces glucose
The book doesn’t give a cure, but I think you trim any contaminated leaves to save the majority

Question 15

Talk about Rose Black Spot

What type of disease, how spread, symptoms, dangers, cure

Answer 15

It is a fungus that causes purple or black spots to develop on the leaves of rose plants (“Who’d have guessed” quote book). 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 can treat the disease using fungicides and by stripping the plant of its affected leaves. These leaves then need to be destroyed so the fungus can’t spread to other healthy rose plants

Question 16

Talk about Malaria

What type of disease, how spread, symptoms, dangers, cure

Answer 16

It is a protist disease. Part of the malarial protist’s life cycle takes place inside the 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, and it can be fatal
The spread of malaria can be stopped by stopping mosquitoes from breeding, and people can be protected from mosquitoes using insectides and mosquito nets

Question 17

Talk about Salmonella

What type of disease, how spread, symptoms, dangers, cure

Answer 17

It is a bacterial disease that causes food poisoning
Infected people can suffer from fever, stomach cramps, vomiting and diarrhoea, and these symptoms are caused from the toxins that bacteria produce when reproducing
You can get Salmonella food poisoning by eating food that’s been contaminated with its bacteria (e.g. eating a chicken that caught the disease whilst it was alive, or prepared in unhygienic conditions)
In the UK, poultry (chickens for example) are vaccinated against Salmonella to control the spread of the disease

Question 18

Talk about Gonorrhoea (I know right)…

What type of disease, how spread, symptoms (sorryy), dangers, cure

Answer 18

Is’s a STD. but it is caused by bacteria.
Symptoms include pain when urinating, and thick yellow/ green discharge from the gametes is the polite word I’m guessing as I don’t want to think about it, but remember it affects both males and females
Gonorrhoea was originally treated with an antibiotic called penicillin, but now it is more difficult 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

Question 19

What is 1 of 4 ways of preventing the spread of diseases?

Answer 19

Being hygienic (washing hands)
Destroying vectors (prevents disease being passed on if nothing carries it - insectides or destroying habitat so they can't breed)
Isolating infected individuals (with communicable diseases, prevents it from being passed on to anyone else)
Vaccination (they can't develop the infection and then pass it on to someone else)

Question 20

What prevents pathogens from entering the body in the first place?

Answer 20

Skin is a barrier
Skin also secretes antimicrobial substances which kill pathogens
Hairs and mucus trap particles that contain pathogens
Scabs are formed/ blood clots to cover open wounds prevent the entry of pathogens

Question 21

What defence systems inside the body) other than white blood cells) fight pathogens?

Answer 21

The trachea and bronchi (breathing pipework) secrete mucus to trap pathogens
The trachea and bronchi are also lined with cillia, which are hair-like structures which waft the mucus up to the back of the throat where it can be swallowed (and destroyed in the stomach I guess)
The stomach produces hydrochloric acid kill pathogens that managed to get that far from the mouth

Question 22

What are the 3 ways that white blood cells destroy pathogens?

Answer 22

Consuming them - they engulf foreign cells and digest them (called phagocytosis)
Producing antibodies - pathogens have unique antigens on their surface. When some white blood cells come across a foreign antigen they don’t recognise, they produce proteins called antibodies to lock onto the invading cells so they can’t be found and destroyed by other white blood cells. The antibodies produces are specific to that type of antigen.
Antibodies are then produced rapidly and carried around the body to find all similar bacteria or viruses. If the person is infected with the same pathogen again, the white blood cells will rapidly produce antibodies to kill it - so they are naturally immune
Producing antitoxins - they conteract toxins produced by invading bacteria

Question 23

Give the fancy word for essentially, white blood cells getting hungry so eating diseases as a snack

Answer 23

Phagocytosis

Question 24

What are the white blood cells that produce antibodies also know as if your a posh scientist?

Answer 24

B-lymphocytes

Question 25

When you’re infected with a new pathogen, your body will immediately start to deal with it and you’ll never feel ill. True or false?

Answer 25

False - it can take a while for the white blood cells to learn how to deal with it, and by that time you can be quite ill

Question 26

What does a vaccination do? How does it work?

Answer 26

It injects small amounts of a dead, weak or inactive pathogen. These carry antigens, so the body produces antibodies to attack them even though it is harmless.
The next time you are exposed to this pathogen, the memory cells (or B cells & T cells?)had recorded how to kill it, so you don’t need to spend a few days learning how to (which could mean death), your body is immediately able to mass-produce antibodies to kill off the pathogen

Question 27

Which of these does the vaccine MMR contiain?

a) Malaria
b) Mumps
c) Measles
d) Mortallo
e) Rubato
f) Rubella

Answer 27

b) Mumps
c) Measles
f) Rubella (German measles?)

Question 28

Will vaccinating more children against measles lead to an increase or decrease in the pathogen? Why?

Answer 28

A decrease in the pathogen, because more vaccination means children are less likely to come into contact with the virus, so it can’t spread

Question 29

Give some pros and cons of vaccination

Answer 29

+ Vaccines have helped control lots of commuicable diseases that were once common in the UK (e.g. polio, measles, whooping cough, rubella, mumps, tetanus). Small pox no longer occurs at all, and polio infections have fallen by 99%
+ Big outbreaks of disease - called epidemics - can be prevented if a large percentage of the population is vaccinated. That way, even the people who aren’t vaccinated aren’t likely to catch the disease because fewer people are able to pass it on. But if a significant number aren’t vaccinated, the disease can quickly spread through them and cause lots of people to be ill at the same time
- They don’t always work, sometimes they don’t give immunity
- You can sometimes have a bad reaction to a vaccine (e.g. swelling, or maybe serious effects such as fever or seizures) but bad reactions are rare.
(i mean, if you read the risks on cough medicine or something simple like that, some of the side effects are worse than the cough. Kidding?!)

Question 30

Some drugs can cure the problem, but what do other drugs do?

Answer 30

Relieve the symptoms

Question 31

Give some examples of drugs that

a) Relieve pain
b) Kill pathogens/ cure disease

Answer 31

a) Painkillers, “cold remedies”

b) Penicillin - antibiotics

Question 32

How can bacteria can become resistant to antibiotics?

Answer 32

Bacteria can mutate, which can cause them to be resistant to certain antibiotics. (This often happens if you stop taking the antibiotic when there are still bacteria alive. This surviving bacteria can then mutate, and reproduce with the new strain of resistant bacteria)

If you have an infection, some of the bacteria might be resistant to antibiotics. This means that when you treat the infection, only the non-resistant strains of bacteria will be killed. The individual resistant will survive and reproduce, and the population of the resistant strain will increase. This is an example of natural selection

Question 33

Give an example of natural selection

Answer 33

When bacteria that has developed antibacterial resistance survives and reproduces, causing the population of the resistant strain to increase

Question 34

What is MRSA?

Answer 34

(Meticillin-resistant Staphylococcus aureus) - a resistant strain which can’t be treated by antibiotics. This one causes serious wound infections and is resistant to the powerful antibiotic meticillin

Question 35

How can you slow down the rate of developing resistant strains?

Answer 35

It is important for doctors to stop over-prescribing antibiotics. So they won’t prescribe them for a sore throat for example, but only for more serious conditions.
It is also important to finish the whole course of antibiotics and not just stopping once you feel better

Question 36

Many drugs originally come from plants. True or false?

Answer 36

True - plants produce a variety of chemicals to defen themselves from pests and pathogens

Question 37

Talk about how the following medicines came from traditional cures - plants

a) Aspirin
b) Digitalis

Answer 37

a) Used as a painkiller and to a lower fever. Developed from a chemical found in willows
b) Used to treat heart conditions. Developed from a chemical found in foxgloves

Question 38

What drug was extracted from microorganisms? Who and how?

Answer 38

Alexander Flemming was clearing out some Petri dishes with bacteria. He noticed that the dishes of bacteria also had mould on it and the area around the mould was free of the bacteria.
He found that the mould (Penicillium notatum) was producing a substance that killed the bacteria - this is penicillin

Question 39

How are drugs made nowadays?

Answer 39

Large scale in the pharmaceutical industry - they’re synthesised by chemists in labs. However, the process may start with a chemical extracted from plants

Question 40

There are 3 main stage of drug testing. Talk about the 1st one

Answer 40

Preclinical testing
Drugs are tested on human cells and tissues in the lab
However, you can’t use human cells and tissues to test drugs that affect whole or multiple body systems (e.g. testing a drug for blood pressure must be done on a whole animal because it has a complete & intact circulatory system)

Question 41

There are 3 main stage of drug testing. Talk about the 2nd one

Answer 41

Next step of preclinical testing
Drugs are tested on live animals. This is to test the efficacy (if it works & produces effect looking for), to find out its toxicity (how harmful it is) and to find the best dosage (the concentration that should be given, and ho often)
The law in Britain says any new drug must be tested on 2 different live mammals. Some people think it’s cruel, but others believe it’s the safest way to make sure it isn’t toxic or dangerous before given to humans

Question 42

There are 3 main stage of drug testing. Talk about the 3rd one

Answer 42

Clinical trials
Drugs are tested on human volunteers. First on healthy volunteers, to check there are no harmful side effects when the body is working normally. At the start of the trial, a very low dosage is given, then gradually increased.
If the results are good, it can be tested on people suffering from the illness The optimum dose is found (the most effective dose with the least side effects)
To test how this drug works, patients are put randomly into 2 groups. One is given the new drug, and another is given the placebo. This is so the doctor can see the actual difference the drug makes - it allows for the placebo effect (when the patient expects it to work so feels better, even though the treatment isn’t doing anything
Clinical trials are blind - the patient in the study definitely doesn’t know if they’re getting a placebo or a real drug, and often they are double-blind, so the doctor doesn’t know either. This removes bias, so the doctors monitoring the patients aren’t subconsciously influenced and only paying attention to the group getting the real drug

The results of drug testing aren’t published until they’ve been through peer review (other scientists checking). This helps to prevent false claims

Question 43

What is a placebo

Answer 43

Often a sugar pill, a drug which looks and tastes exactly like the real drug, but does nothing to the body (contains no medicinal properties, but due to the placebo effect he patient may believe it works then become better)

Question 44

What is a double blind trial?

Answer 44

When neither the doctor or the patient know which group in the clinical trials has the placebo or the real thing

Question 45

What is peer review?

Answer 45

When other scientists check that the work is valid and has been carried out rigorously.
As the results of drug tests & trials aren’t published until they have been through peer reviews this helps to prevent false claims,

Question 46

Sum up the stages of drug testing

Answer 46

1) Preclinical tests - tested on human cells and tissues in the lab (+ not fatal as not connected to anyone, - can’t see effects on a whole or multiple body systems)
2) Preclinical tests again - testing on live animals to test for efficacy & toxicity & best dosage (+ more accurate as closer to humans, - unethical, but law in UK says test on 2 different live mammals)
3) Clinical trials - testing on healthy human volunteers to check it causes no harm on healthy body (starts low dosage), THEN tested on those with illness in 2 groups, one given placebo & other given actual drug to see how effective the drug actually is. It is double-blind, then peer reviewed before any results go out (+effective, double-blind removes bias of doctors ignoring placebo patients. - placebo patients could be very ill by time trial is over & too late to get actual drug [that isn’t from book, so who knows, but you know it has happened in Philomena]

Question 47

What is the optimum dosage?

Answer 47

The amount that is the most effective and with the least side effects