Infection and Response

Question 1

What is a communicable disease?

Answer 1

A disease that can be spread from person to person or between animals and people such as measles and malaria.

Question 2

What is a non-communicable disease?

Answer 2

A disease that can’t be spread between people or between animals and people such as asthma, cancer and coronary disease.

Question 3

What are pathogens?

Answer 3

Microorganisms that enter the body and cause disease.

Question 4

How are different examples of pathogens spread?

Answer 4

› viruses live inside cells and replicate themselves using cells’ machinery to produce many copies of themselves which then burst releasing all the new viruses.
›protists are single-celled eukaryotes who are parasites that live on or inside other organisms and can cause damage. They are normally spread by a vector which doesn’t get the disease itself.
› fungi are single-celled which can be made up of hyphae which can then grow and penetrate human skin and the surface of plants causing diseases.

Question 5

How can pathogens be spread?

Answer 5

› water - drinking or bathing in dirty water (cholera).
›air - breathed in when someone sneezes or coughs (influenza virus).
›direct contact - touching contaminated surfaces including skin (athlete’s foot).

Question 6

How does bacteria make you feel ill?

Answer 6

By producing toxins that damage your cells and tissues.

Question 7

What are ways to reduce/prevent the spreading of diseases?

Answer 7

› hygienic.
› destroying vectors.
›isolating infected individuals.
› vaccination.

Question 8

Describe the disease measles.

Answer 8

› virus.
› spread by droplets from an infected person’s sneeze of cough.
› red skin rash and fever.
› measles can lead to pneumonia or encephalitis making it serious an even fatal if complications arise.
› can be prevented through vaccinating people when children.

Question 9

Describe the disease HIV.

Answer 9

› virus.
› spread by sexual contact or bodily fluids such as blood (when sharing needles when taking drugs).
› flu-like symptoms for a few weeks. then gone for several years.
›virus attacks immune cells.
› badly damaged immune system leads to it not copping with the infections or cancers.
› can be prevented through the use of condoms, avoiding sharing needles and antiretrovirals.

Question 10

Describe the disease tobacco mosaic virus.

Answer 10

› virus.
› mosaic pattern on leaves of plants, discolouration.
›discolouration = plant can’t carry out photosynthesis so it affects growth.

Question 11

Describe the disease salmonella.

Answer 11

› bacteria that causes food poisoning.
› spread by eating contaminated food.
› causes fever, stomach cramps, vomiting and diarrhoea.
› to prevent you could vaccinate the poultry and keep the food preparation hygienic.

Question 12

Describe the disease gonorrhoea.

Answer 12

› bacteria.
› sexually transmitted disease.
› causes pain when urinating, yellow or green discharge from vagina or penis.
› condoms and antibiotics can prevent it from spread.

Question 13

Describe the disease rose black spot.

Answer 13

› fungus.
› spread by water or wind.
› causes purple or black spots to develop on the leaves of rose plants which can turn yellow and drop off.
› less photosynthesis so bad growth.
› fungicides or stripping the plant of its affected leaves can treat the disease.

Question 14

Describe the ways in which the human body defends itself against the tuberculosis bacterium.

Answer 14

› skin stops the bacterium entering the body.
› blood cots to stop bacteria entering.
› stomach acid/hydrochloric acid will kill the bacterium if it is in food.
› nose have mucus to trap the bacteria.
› nose have cilia/hair to move mucus out.
› white blood cells destroy the bacteria if infected.
› by phagocytosis.
› by antibodies.
› by antitoxins.

Question 15

What is the role of the immune system?

Answer 15

To attack and destroy any pathogens that make it into your body.

Question 16

How do white blood cells destroy pathogens?

Answer 16

1. By consuming them where they engulf foreign cells and digest them which is called phagocytosis.
2. Producing antibodies.
3. Producing antitoxins.

Question 17

How does vaccination work?

Answer 17

It involves injecting small amounts of dead/inactive pathogens which carry antigens causing your body to produce antibodies to attack them even though the pathogen is harmless.
Therefore, if the live pathogen of the same type appear after that, the white blood cells can rapidly mass-produce antibodies to kill it off.

Question 18

How are antibiotics and painkillers used to treat diseases?

Answer 18

PAINKILLERS - drugs that relieve pain and reduce symptoms but don’t kill the pathogens.
ANTIBIOTICS - such as penicillin kill or prevent the growth of the bacteria without killing your own body cells however they don’t destroy viruses such as the flu.

Question 19

Give 3 limitations of using antibiotics.

Answer 19

›bacteria can mutate causing them to become resistant to an antibiotic.
› some of the bacteria might be resistant to antibiotics in an infection so when its treated, only the non-resistant strains of bacteria will be killed leading to the resistant bacteria reproducing. This is an example of natural selection.
› over-prescribing antibiotics.
›not finishing the whole course of antibiotics could worsen bacteria.

Question 20

What is a protist?

Answer 20

A single celled organism that causes diseases.

Question 21

What are antigens?

Answer 21

Proteins specific to each pathogen.

Question 22

What is meant by the term lag time?

Answer 22

The first time a pathogen enters the body, the response takes a day or two.

Question 23

What is meant by the term immunity?

Answer 23

When your immune system can respond so quickly that the pathogen is destroyed before any symptoms are felt. Immunity can be passed on from mother to baby.

Question 24

What is meant by the term herd immunity?

Answer 24

When enough people are vaccinated, even the people who haven’t vaccinated, are protected because the pathogen can no longer spread.

Question 25

What is a placebo?

Answer 25

A fake drug used in clinical trials.

Question 26

How are new drugs tested?

Answer 26

› preclinical testing - drugs tested on human cells and tissues in the lab.
[if the drugs tested affect the whole or multiple body systems so then it is tested on live animals].
› clinical trial - using healthy volunteers, give small doses of the drug to see if safe.
› if safe, it is tested on a small group of patients to see if it treats the disease.
›bigger clinical trials - finding the optimum dose.

Question 27

What is a blind trial?

Answer 27

Where the doctor knows who has the drug and who has the placebo but the patient doesn’t.

Question 28

What is a double blind trial?

Answer 28

Where neither the doctor or patient know who has the drug and who has the placebo.

Question 29

Name three drugs and their source.

Answer 29

> aspirin.
   ↳ painkiller to low fever.
   ↳ chemical found in willow.
> digitalis.
   ↳ heart drug.
   ↳ chemical found in foxgloves.
> penicillin.
   ↳ antibiotic.
   ↳ found in penicillium mould.

Question 30

What three things are drugs tested for?

Answer 30

> toxicity.
↳ how harmful the drug is.
efficacy.
↳ whether the drug works and produces the effect you’re looking for.
dosage.
↳ the concentration that sold be given and how often it should be given.

Question 31

What is malaria an example of?

Answer 31

A protist pathogen.

Question 32

What is are the symptoms of malaria?

Answer 32

> repeating episodes of fever which can be fatal.
> sweats and chills.
> headaches.
> vomiting.
> muscle pains.
> diarrhoea.

Question 33

How is malaria transmitted/spread?

Answer 33

Female anopheles mosquitoes are the vectors that spread malaria. They feed on infected animals and infects other animals.

Question 34

What are 3 ways to prevent malaria?

Answer 34

Malaria is hard to prevent because mosquitoes breed in large quantities making their population wide.

> removing/covering bodies of water.
using insecticides.
using mosquito nets.

Question 35

How can plant diseases be detected?

Answer 35

> stunted growth.
> spots on leaves.
> areas of decay.
> growths.
> malformed stems or leaves.
> discolouration.
> the presence of pests.

Question 36

What are the physical defence responses to resist invasion of microorganisms in plants?

Answer 36

> cellulose cell walls
↳ form a physical barrier against pathogens that make it past the waxy cuticle.
tough waxy cuticle on leaves
↳ barrier to stop pathogens entering.
layers of dead cells around stems which fall off such as the outer part of the bark on trees.
↳ barrier to stop pathogens entering.

Question 37

What are the chemical defence responses to resist invasion of microorganisms in plants?

Answer 37

> antibacterial chemicals
↳ kill bacteria.
poisons to deter herbivores
↳ such as tobacco plants, foxgloves and deadly nightshade.

Question 38

What are the mechanical defence responses to resist invasion of microorganisms in plants?

Answer 38

> thorns and hairs deter animals
↳ stop animals from touching and eating them.
leaves which droop or curl when touched
↳ can prevent themselves from being eaten by knocking insects off themselves and moving away from things.
mimic to trick animals.