4.3 Infection and Response

Question 1

What are pathogens?

Answer 1

Microoraganisms that cause infectious diseases

Question 2

What can pathogens infect?

Answer 2

Plants

Animals

Question 3

How can pathogens be spread?

Answer 3

Direct contact
Water or air
Vectors

Question 4

What are Vectors?

Answer 4

Organisms that carry and pass on the pathogen without getting the disease

Question 5

How can the spread of disease be reduced?

Answer 5

Simple hygiene measures e.g. Washing hands
Destroying vectors
Isolating infected individuals
Giving people at risk a vaccination

Question 6

How did viruses cause damage to cells?

Answer 6

Reproduce rapidly in body cells

Question 7

Describe measles

Answer 7

• Symptoms are fever and red skin rash
• Measles is spread by breathing in droplets from sneezes and coughs
• fatal complications
• most young people vaccinated

Question 8

Describe HIV

Answer 8

• spread through sexual contact and sharing body fluids
• first flu like illness
• if untreated virus enters lymph nodes and attacks body’s immune cells

Question 9

How do bacteria damage cells?

Answer 9

Directly or produce toxins that damage tissues

Question 10

Describe Salmonella

Answer 10

Type of food poisoning caused by bacteria
Bacteria ingested in food
Secrete toxins which cause fever abdominal cramps vomiting and diarrhoea
Chicken and eggs can contain bacteria

Question 11

Describe gonorrhea

Answer 11

Sexually transmitted disease
Spread through sexual contact
Thick yellow or green discharge from vagina or penis
Easily hearted with penicillin but resistant trains now appeared
Contraception can act as a barrier and protects

Question 12

What are Protists?

Answer 12

Single cells organisms that are eukaryotic

Question 13

Describe malaria

Answer 13

Caused by protists
The protists uses mosquito as a vector
Passed on by being bitten by mosquito
Malaria causes severe fever 
Kill mosquitos or use nets

Question 14

Describe rose black spot

Answer 14

Fungal disease
Spread when spores are carried from plant to plant by water or wind
Black spots develop on leaves
Stunted growth due to reducing of photosynthesis
Fungicides can be treatment
Remove affected leaves also is a treatment

Question 15

Name some non-specific defences of the body that work against all pathogens

Answer 15

Glands in stomach Wall that produce hydrochloric acid that kills bacteria in food

Sebaceous gland in skin that produces sebum-kills bacteria and fungi

The nose traps particles

Enzymes in tears destroy microorganisms

Goblet cells create mucus which traps particles and bacteria

Question 16

What does the immune system do?

Answer 16

Tries to destroy pathogens that enter the body

Question 17

What does phagocytosis involve?

Answer 17

Pathogen being surrounded engulfed and digested

Question 18

How do white blood cells help to defend against pathogens?

Answer 18

Phagocytosis

Production of special protein molecules called antibodies which attach to antigen molecules on the pathogen

Production of antitoxins which are chemicals that neutralise the poisonous effects of the toxins

Question 19

What happens when someone has a vaccination?

Answer 19

Small quantities of dead or inactive forms of pathogen are injectors into the body

Vaccination stimulates the white blood cells to produce antibodies and to develop immunity

Question 20

Why does vaccination work?

Answer 20

If a large proportion of the population can be made immune to a pathogen, then the pathogen cannot be spread easily

Question 21

What are antibiotics?

Answer 21

Medicines that kill bacteria inside the body. However they cannot destroy viruses

Question 22

What is MRSA?

Answer 22

A strain of bacteria that is resistant to antibiotics

Question 23

What can we do to reduce the rate at which resistant strains of bacteria develop?

Answer 23

Doctors should not prescribe antibiotics unless they are really needed, for non serious infections and viral infections

Patients must complete their course of antibiotics so that all bacteria are killed and none survive to form resistant strains

Question 24

What have new pain killers been developed to do?

Answer 24

To treat the symptoms of disease but they do not kill the pathogens

Question 25

Why are antiviral drugs needed?

Answer 25

That will kill viruses without damaging the body's tissues

Question 26

Why are new antibiotics needed?

Answer 26

Because resistant strains of bacteria are developing

Question 27

What is digitalis?

Answer 27

A heart drug that originates from foxgloves

Question 28

What is aspirin?

Answer 28

A pain killer that originates from willow

Question 29

What is penicillin?

Answer 29

Discovered by Alexander Fleming from the Penicillium mould

Question 30

Why are new medical drugs tested?

Answer 30

New medical drugs have to be tested and trialled before being used to make sure they are safe

Question 31

If a drug is found to be safe, it is then tested on patients to:

Answer 31

See if it works Find out the optimum dose

Question 32

What are double-blind trials?

Answer 32

Some patients are given a placebo and others given the drug Neither doctors or patient knows who has received drug

Question 33

What is a monoclonal antibody?

Answer 33

Produced from a single cell that has divided to make many cloned copies of itself

Question 34

What do monoclonal antibodies bind to?

Answer 34

One type of antigen, so they can be used to target a specific chemical or specific cells in the body

Question 35

What is a hybridoma?

Answer 35

Combining a mouse cell and a tumour cell

Question 36

How can monoclonal antibodies be used?

Answer 36

In pregnancy tests In laboratories In research To treat some diseases

Question 37

How are monoclonal antibodies used in pregnancy tests?

Answer 37

Binds to the hormone HCG found in urine during early pregnancy

Question 38

How are monoclonal antibodies used in laboratories?

Answer 38

To measure the levels of hormones and other chemicals in blood or to detect pathogens

Question 39

How are monoclonal antibodies used in research?

Answer 39

To locate or identify specific molecules in a cell or tissue by binding to them with a fluorescent dye

Question 40

How are monoclonal antibodies used to treat some diseases?

Answer 40

For example in cancer they can be used to deliver a radioactive substance, a toxic drug or a chemical that stops cells dividing, specifically the cancer cells

Question 41

Why are monoclonal antibodies not widely used?

Answer 41

They created more side effects than expected, so they are not widely used.

Question 42

Name signs that show a plant may be diseased

Answer 42

``` Stunted growth Spots on leaves Areas of decay Growths Malformed stems or leaves Discolouration The presence of pests ```

Question 43

How can you identify a plant disease?

Answer 43

Consulting a garden manual or website Taking infected plants to a laboratory Using testing kits

Question 44

What can plants be infected by?

Answer 44

Viral bacterial and fungal pathogens as well as insects

Question 45

Describe TMV

Answer 45

Widespread pathogen Infects tobacco plants and other plants such as tomatoes Produces distinctive mosaic pattern of discolouration on the leaves m, which reduces chlorophyll content and affects photosynthesis It effects growth of plant due to lack of photosynthesis

Question 46

Why are aphids?

Answer 46

Small insects often known as greenfly or black fly. They feed form phloem taking sugars away from the plant

Question 47

What does nitrate deficiency cause?

Answer 47

Stunted growth, because nitrates are needed for protein synthesis

Question 48

What does magnesium deficiency cause?

Answer 48

Chlorosis, because magnesium ions are needed to make chlorophyll

Question 49

Name some physical defences of plants

Answer 49

Cellulose cell walls A tough waxy cuticle on leaves Layers of dead cells around stems, which fall off and take pathogens with them

Question 50

Name some chemical defences of plants

Answer 50

Antibacterial chemicals which are made by plants such as mint and witch hazel Poisons deter herbivores, which are made by plants such as tobacco, foxgloves and deadly nightshade

Question 51

Name some mechanical adaptations of plants

Answer 51

Thorns and hairs to deter animals from animals from eating or touching them Leaves that droop or curl when touched Mimicry to trick animals into not eating them or not paying eggs on leaves e.g. The white dead nettle does not sting but it looks very similar to the stinging nettle