infection and response

Question 1

What are white blood cells made from?

Answer 1

white blood cells are produced by the bone marrow

Question 2

what do lymphocytes do?

Answer 2

They recognize proteins on the surface of pathogens called antigens. Lymphocytes detect that these are foreign not naturally occurring within your body and produce antibodies. The antibodies cause pathogens to stick together and make it easier for phagocytes to engulf them.

Question 3

what do phagocytes do?

Answer 3

Phagocytes surround any pathogens in the blood and engulf them. They are attracted to pathogens and bind to them. The phagocytes membrane surrounds the pathogen and enzymes found inside the cell break down the pathogen in order to destroy it. As phagocytes do this to all pathogens that they encounter, they are called ‘non-specific’.

Question 4

What is the immune system made up of?

Answer 4

white blood cells, antibodies, lymph nodes, spleen, thymus gland

Question 5

What is measles?

Answer 5

measles is a viral disease. it is spread via droplets from an infected persons’ sneeze or cough. measles can lead to death if there is complications. most people are vaccinated at a young age

Question 6

What is HIV?

Answer 6

HIV is a virus is spread by sexual contact, or by exchanging bodily fluids like blood. HIV causes flu-like symptoms. The virus attacks the immune cells, and if the immune system is damaged, it cannot cope with any other infections.

Question 7

what is tobacco mosaic virus (TMV)?

Answer 7

TMV is a virus that affects many species of plants. It causes a mosaic pattern on the leaves of plants - some parts become discoloured. This means photosynthesis cannot be carried out (as well), affecting growth.

Question 8

what is rose black spot?

Answer 8

rose black spot is a fungus that causes purple or black spots to develop on the leaves of rose plants, they sometimes turn yellow and drop off. This means there is less photosynthesis, so the plant cannot grow very well.

Question 9

what is malaria?

Answer 9

malaria is caused by a protist. A mosquito is a vector (carrier) and infect other animals. Malaria causes repeating episodes of fever (can be fatal)

Question 10

what are bacteria?

Answer 10

bacteria are very small living cells, they produce toxins that damage your cells/tissues, causing you to feel ill

Question 11

what are viruses?

Answer 11

viruses are not cells, they are tiny and reproduce rapidly inside your body. they live inside your cells and replicate inside, causing the cell to burst, releasing all the new viruses

Question 12

what are protists?

Answer 12

protists are single-celled eukaryotes. some are parasites that live on or inside other organisms and are spread by vectors.

Question 13

what are fungi?

Answer 13

Some are singled celled, others have a body made up of hyphae. These hyphae can grow and penetrate living surfaces, causing disease.

Question 14

How can pathogens be spread?

Answer 14

• water - drinking or bathing in dirty water
• air - carried in the air and inhaled or water droplets in air
• direct contact - touching contaminated surfaces, including skin

Question 15

What is phagocytosis?

Answer 15

The process by which cells engulf and digest foreign substances, such as bacteria.

Question 16

Summarise the white blood cells role in defence

Answer 16

1) the white blood cells can engulf foreign cells and digest them. This is phagocytosis
2) each invading pathogen has unique molecules (antigens) on its surface. When some types of white blood cell come across a foreign antigen they produce proteins called antibodies to lock onto the invading cells so it can be found and destroyed
3) antibodies are rapidly produced and carried around the body
4) if the person is infected with the same pathogen again the white blood cells will rapidly produce the antibodies to kill it

Question 17

what is salmonella?

Answer 17

A type of bacteria that causes food poisoning. Symptoms include fever and sickness. These are caused by the toxins produced by bacteria. You can get salmonella food poisoning by eating contaminated food.

Question 18

what is Gonorrhoea?

Answer 18

A sexually transmitted disease (STD). It is caused by bacteria and is passed on by sexual contact. Symptoms include pain whilst urinating and a yellow/green discharge. In the past, it was treated with Penicillin, but this is more difficult now as the bacteria has become resistant.

Question 19

How can the spread of disease be reduced or prevented?

Answer 19

1) Being hygienic - having basic hygiene like washing your hands thoroughly
2) destroying vectors - getting rid of the organisms by using insecticides or destroying their habitat
3) isolating infected individuals - if it is a communicable disease, it prevents the spread
4) vaccinations - vaccinating against a disease means the person has a higher chance of fighting a disease, and means they cannot develop and pass on the infection

Question 20

what is a vaccination?

Answer 20

protects you from future infections

Question 21

how do vaccines work?

Answer 21

vaccinations involve injecting small amounts of dead or inactive pathogens. These carry the antigens, causing your body to produce antibodies to attack them (even though the pathogen is harmless). This means if live pathogens of the same type appear in future, the white blood cells can rapidly mass-produce the antibodies to kill the pathogen.

Question 22

What are the two advantage of vaccines?

Answer 22

1 - help to control lots of communicable diseases that were one common in the UK (like measles and tetanus). Smallpox no longer occurs at all, and polio infections have fallen by 99%
2 - Big outbreaks of disease (epidemics) can be prevented if a large amount of the population has been vaccinated. This means those unvaccinated are less likely to get ill as less people have the disease overall

Question 23

what are the two disadvantages of vaccinations?

Answer 23

1 - vaccines do not always work, sometimes a person does not become immune
2 - you could have a bad reaction to a vaccine (having swelling or something more serious like a fever or seizures), however bad reactions are very rare.

Question 24

Describe the role of painkillers:

Answer 24

Painkillers are drugs that relieve pain, but they do not affect the cause of the disease or kill pathogens.

Question 25

Describe the role of antibiotics:

Answer 25

Antibiotics prevent the growth of/kill the bacteria causing the disease. Different antibiotics treat different bacteria.

important: ANTIBIOTICS DO NOT DESTROY VIRUSES!

Question 26

What happens when bacteria become resistant to antibiotics?

Answer 26

The bacteria mutates, so, if you have an infection, some of the bacteria is resistant. This means that it is unaffected by the antibiotics, so you may need to use a different treatment.

Question 27

Where is aspirin (used as a painkiller and to lower a fever) from?

Answer 27

Willow bark

Question 28

where is digitalis (used to treat heart conditions) from?

Answer 28

Foxgloves

Question 29

How did Alexander Fleming discover penicillin?

Answer 29

• He was clearing out some petri dishes containing bacteria. He noticed one had mould and the area around the mould was clear of bacteria
• He found the mould on the dish was producing a substance that killed bacteria - penicillin

Question 30

what are the three stages of drug testing?

Answer 30

1 - drugs are tested on human cells and tissues in a lab
2 - the drug is tested on live animals, to test for efficacy (if it works), and toxicity (how harmful), and to find the best dosage. In the UK, it must be tested on 2 different animals
3 - it is tested on human volunteers in a clinical trial in this order: healthy volunteers, infected volunteers, then 2 groups with 1 placebo (blind test - patients do not know but the doctor does), then a double blind test (volunteer nor doctor knows).
If all these stages are successful, it is peer reviewed then rolled out to the public

Question 31

What are monoclonal antibodies?

Answer 31

Identical antibodies

Question 32

how are monoclonal antibodies produced?

Answer 32

A hybridoma cell is made from a mouse B-lymphocyte and a tumour cell as this will cause it to rapidly divide, and be identical.

Question 33

What are monoclonal antibodies used for?

Answer 33

• treat diseases
• in labs to find specific substances
• pregnancy tests

Question 34

how are monoclonal antibodies used in pregnancy tests?

Answer 34

• a hormone can be found in women only when they are pregnant
• the part of a pregnancy test that you wee on has some of the antibodies to the hormone
• the test strip (where you see the result) has more antibodies to the hormone, these are stuck in place
• If you are pregnant:
  1) the hormone will bind to the antibodies attached to the coloured beads
  2) the urine moves up the stick, carrying the hormone and beads
  3) the beads and hormone bind to the antibodies on the test strip, so it turns blue.

Question 35

what are the pros and cons of monoclonal antibodies?

Answer 35

P- they can be used for cancer treatment, without effecting the other cells too much
C - it has more side effects than originally planned, so it is not as widely used as scientists thought.

Question 36

what are signs a plant is infected?

Answer 36

• stunted growth
• abnormal growths
• spots on leaves
• malformed parts
• patches of decay
• discolouration

Question 37

what are the three types of plant defences?

Answer 37

• physical
• mechanical
• chemical

Question 38

give an example of a physical defence:

Answer 38

• waxy cuticle
• cell walls
• layers of dead cells

Question 39

give an example of a mechanical defence:

Answer 39

• thorns or hairs
• droop/curl when touched
• mimic other organisms

Question 40

give an example of a chemical defence:

Answer 40

• poisons
• antibacterial chemicals which kill bacteria