TOPIC 3 INFECTION AND RESPONSE

Question 1

what is a pathogen

Answer 1

microorganisms that enter the body and cause communicable diseases
-BOTH plants and animals can be infected

Question 2

Examples of diseases caused by viruses

Answer 2

-common cold
-flu
-measles

Question 3

how does bacteria make us feel ill

Answer 3

-small cells that produce toxins that damage your cells and tissues

Question 4

what makes us feel ill in viruses

Answer 4

-they live inside cells and replicate using cell machinery to produce many copies of themselves
-the cells burst which releases new viruses

Question 5

state 3 ways pathogens are spread

Answer 5

1. contaminated water, (drinking dirty water)
2. air (pathogens can be carried in air and breathed in)
3. direct contact (by touching contaminated surfaces e.g skin)

Question 6

explain the viral disease measles

Answer 6

-spread by droplets from an infected persons sneeze or cough
symptoms a red skin rash and fever
-leads to pneumonia
-prevent, vaccinated when young

Question 7

state another virus

Answer 7

HIV
-spread by sexual contact or exchanging bodily fluids
-SYMPTOMS flu-like symptoms
-attacks immune cells
-controlled by antiretrovial drugs

Question 8

what is the disease TMV

Answer 8

-tobacco mosaic virus, a widespread plant pathogen
-affects many species of plants
-cause a mosaic pattern on leaves (discoloured)
-**effect **plant cannot carry out photosynthesis

Question 9

state a fungal disease

Answer 9

rose black spot
-causes purple or black spots to develop on leaves and the leaves turn yellow and drop off
-the loss of leaves means that there are less chloroplasts for photosynthesis
-spreads through environment in water or by wind
-**treat **by stripping the plant of its affected leaves

Question 10

state a disease caused by a protist

Answer 10

malaria
-mosquitos are vectors that pick up malarial protst when they feed on infected animal
-every time the mosquito feeds on another animal it infects it
symptoms repeated fevers and shaking
-reduce spread by mosquito nets or stopping them from breeding

Question 11

state 2 bacterial diseases

Answer 11

-salmonella
-gonorrhoea

Question 12

what is salmonella

Answer 12

-a type of bacteria that causes food poisoning, found in the gut of many animals
-causes fever, stomach cramps, vomitting
-get it by eating contaminated food
-most poultry in UK is given a vaccination against this

Question 13

what is gonorrhoea

Answer 13

-sexually transmitted disease (STD)
-**transmitted by sexual contact
-symptom pain when urinating, yellow discharge from the vagina
-treated by **antibiotics
-use condoms to stop spread

Question 14

4ways to reduce disease

Answer 14

1. be hygenic, wash hands with soap thoroughly
2. destroy vectors
3. isolate infected individuals
4. vaccinations

Question 15

how does the skin act as a defence system

Answer 15

-acts as a barrier to pathogens

Question 16

non-specific defence systems of the human body against pathogens

Answer 16

skin
nose
trachea and bronchi
stomach.

Question 17

how does your nose act as a defence system

Answer 17

-hair and mucus trap particles that contain pathogens

Question 18

how does the trachea and bronochi act as a defence system

Answer 18

they secrete mucus to trap pathogens
-lined with cilia

Question 19

how does the stomach act as a defence system

Answer 19

-produces hydrochloric acid

Question 20

How do white blood cells help to defend against pathogens by

Answer 20

-phagocytosis
-production of antibodies
-production of antitoxins

Question 21

Phagocytosis

Answer 21

-Engulf and digest pathogens
-the phagocyte surrounds the pathogen and releases enzymes to digest and break it down to destroy it

Question 22

Antibody production

Answer 22

-lymphocytes produce antibodies
-antibodies are Y shaped proteins and each individual has the potential to make millions of different types of antibodies
-aim of antibody production is to produce the antibody
-is a protein made by lymphocytes that is complementary to an antigen and, when attached, clumps them together and signals the cells they are on for destruction

Question 23

Antitoxin production

Answer 23

-pathogens produce substances which act as toxins which make you feel unwell
-lymphocytes produce antibodies against substances
antitoxin is a protein that neutralises the toxins produced by bacteria

Question 24

what is an antigen

Answer 24

a molecule found on the surface of a cell

Question 25

what does the immune system do if pathogens enter the body

Answer 25

-kicks in to destory them -the white blood cells travel around and when coming across an invading microbe they * consume them * produce antibodies * produce antitoxins

Question 26

describe the 1st process of white blood cells

Answer 26

-engulf cells and digest them -called phagocytosis

Question 27

describe the 2nd process of white blood cells

Answer 27

-invading pathogens have antigens on its surface -start to produce proteins called antibodies -antiboides are produced rapidly -if the person ifnected with the same pathogen again, the persons naturally immune to that pathogen

Question 28

3rd process of white blood cells

Answer 28

-produces antitoxins -counteract toxins produced by invading bacteria

Question 29

how does the spread of pathogens be reduced by immunising a large proportion of population

Answer 29

If a large number of the population are vaccinated, it is unlikely that an unvaccinated individual will become infected with the pathogen

Question 30

State the 3 scenarios for this

Answer 30

-There are no vaccinations and the disease spreads quickly Some of the population are vaccinated and the disease spreads to less people Most of the population are vaccinated and this prevents the spread

Question 31

Vaccination processes

Answer 31

-involves introducing **small quantities** of **dead or inactive forms of a pathogen** into the body to stimulate the white blood cells to produce antibodies. -If the same pathogen **re-enters the body **the white blood cells respond **quickly** to produce the **correct antibodies**, preventing infection.

Question 32

PROS of infections

Answer 32

-they control many communicable diseases that were common -outbreaks of diseases can be prevented if a large percentage of the population is vaccinated

Question 33

CONS of infection

Answer 33

-dont always work -can causes bad reactions, e.g swelling or fever

Question 34

state what relieves symptoms

Answer 34

-painkillers

Question 35

the use of antibiotics and other medicines in treating disease

Answer 35

they kill the growth bacteria but dont destory viruses -greatly reduced the deaths from infections in the last century

Question 36

the use of the antibiotic penicillin

Answer 36

is used to kill or stop the growth of bacteria -It is important that specific bacteria should be treated by specific antibiotics.

Question 37

Advantages of antibiotic uses

Answer 37

-it has greatly reduced deaths from infectious bacterial diseases. -but the emergence of strains resistant to antibiotics is of great concern.

Question 38

why can we not develop drugs that kill viruses

Answer 38

as this damages the body’s tissues.

Question 39

3main stages of drug testing

Answer 39

1. preclincal testing, drugs are tested on human cells and tissues in the lab 2. test drug on live animals - tests for efficacy - tests toxicity - LAW must be tested on 2different live mammals 3. if passes them tests its treated on human volunteers in a clincial trial -then tested on people suffering from the illness

Question 40

State traditional drugs which were extracted from plants and microorganisms

Answer 40

-The heart drug digitalis originates from foxgloves. -The painkiller aspirin originates from willow. -Penicillin was discovered by Alexander Fleming from the Penicillium mould.

Question 41

How are new drugs synthesised

Answer 41

by chemists in the pharmaceutical industry. However, the starting point may still be a chemical extracted from a plant.

Question 42

What has to happen to new medical drugs

Answer 42

-have to be tested and trialled before being used to check that they are safe and effective. -New drugs are extensively tested for toxicity, efficacy and dose. -Preclinical testing is done in a laboratory using cells, tissues and live animals.

Question 43

State what happens at clinical trials

Answer 43

they use healthy volunteers and patients -Very low doses of the drug are given at the start of the clinical trial. -If the drug is found to be safe, further clinical trials are carried out to find the optimum dose for the drug. -In double blind trials, some patients are given a placebo.