2.8 DISEASE, DEFENCE AND TREATMEANT

Question 1

WHAT IS A PATHOGEN?

Answer 1

a micro-organism which causes disease

Question 2

WHAT ARE SOME EXAMPLES OF PATHOGENS?

Answer 2

• bacteria
• virus
• fungi

Question 3

HOW CAN PATHOGENS PASS FROM ONE PERSON TO THE NEXT?

Answer 3

by contact, aerosol, body fluids, water, insects and contaminated food

Question 4

WHAT IS THE CAUSATIVE AGENT OF AIDS?

Answer 4

HIV (passed by blood to blood contact + sexual contact)

Question 5

WHAT IS THE CAUSATIVE AGENT OF CHLAMYDIA?

Answer 5

Chlamydia trachomatis bacterium (passed by sexual contact)

Question 6

WHAT IS THE CAUSATIVE AGENT OF MALERIA?

Answer 6

Plasmodium single celled organism (passed by female mosquitoes)

Question 7

WHAT IS THE EFFECT OF AIDS?

Answer 7

infects lymphocytes which are part of the body’s immune system. Without immunity, the body can become infected with a variety of micro-organisms, e.g. tuberculosis or pneumonia

Question 8

WHAT IS THE EFFECT OF CHLAMYDIA?

Answer 8

could cause infertility in adults. It could also cause conjunctivitis in babies during the process of birth if the mother is infected

Question 9

WHAT IS THE EFFECT OF MALERIA?

Answer 9

causes a fever when it destroys red blood cells in humans

Question 10

WHAT IS THE TREATMENT/PREVENTION OF AIDS?

Answer 10

the use of condoms, and disposable gloves should be used where there is any danger of contact with contaminated blood. Antiviral agents can be used, but they only prevent the multiplication of the virus inside cells and must be taken throughout life

Question 11

WHAT IS THE TREATMENT/PREVENTION OF CHLAMYDIA?

Answer 11

prevented by the use of condoms. It can be treated with antibiotics such as tetracycline or erythromycin

Question 12

WHAT IS THE TREATMENT/PREVENTION OF MALERIA?

Answer 12

Treatment - killing Plasmodium with anti-malarial drugs, such as paludrine or daraprim.
prevention - a vaccine against Plasmodium, killing mosquitoes with insecticide, releasing large numbers of infertile male mosquitoes, biological control of mosquitoes, and use of mosquito nets and repellents

Question 13

WHAT ARE THE TWO WAYS OUR BODY STOPS THE ENTRY OF MICROBES?

Answer 13

Skin - provides physical barrier
Blood clotting - seals wounds and prevents entry through the cut skin

Question 14

WHAT ARE THE TWO WHITE BLOOD CELLS OF DISEASE DEFENCE?

Answer 14

Phagocyte and Lymphocyte

Question 15

WHAT DOES THE LYMPHOCYTE DO?

Answer 15

1) detects the foreign antigen
2) splits itself by mitosis, makes many plasma cells and produces antibodies
3) antibodies are specific to the antigen
4) antibodies attach to the antigens making it a noticeable microbe for phagocytes
5) memory cells are made for immunity to the specific antigen

Question 16

WHAT DOES THE PHAGOCYTE DO?

Answer 16

Detects microbe and engulfs it to break it down.

Question 17

WHAT IS THE PRIMARY IMMUNE RESPONSE?

Answer 17

the response that takes place the first time an individual encounters an antigen. the primary immune response takes time

Question 18

WHAT IS THE SECONDARY IMMUNE RESPONSE?

Answer 18

the response that takes place the second time an individual encounters an antigen. The lymphocytes recognise the antigen so produce antibodies much faster.

Question 19

WHY CAN PEOPLE SUFFER FROM THE FLU MULTIPLE TIME?

Answer 19

the antigens on the surface of the flu virus mutate and change rapidly, giving rise to new strains which have not been previously encountered and so immunity has not developed

Question 20

WHAT IS USED TO MAKE A VACCINE?

Answer 20

non-active, disease-causing micro-organisms, antigens or parts of antigens from disease-causing micro-organisms to stimulate an immune response

Question 21

WHAT IS THE AIM OF A VACCINE?

Answer 21

use antigens from the disease-causing micro-organism to stimulate the production of antibodies specific to the antigen that would protect the body against the pathogen

Question 22

WHY DOES ANTIBIOTIC RESISTANCE HAPPEN?

Answer 22

because of a mutation in the bacteria, which can now pass the resistance between itself. If an infection is then treated by antibiotics, the resistant bacteria survive and reproduce (an example of natural selection), therefore becoming very widespread

Question 23

WHAT IS MRSA?

Answer 23

A superbug (resistant to antibiotics)

Question 24

HOW IS MRSA CONTROLLED?

Answer 24

• more rigorous hygiene in hospital wards
• MRSA screening – testing people to see if they are carrying the bacteria

Question 25

WHAT ARE THE STAGES OF TESTING A NEW DRUG?

Answer 25

1) The drug is tested on human cells grown outside the body in a laboratory.
2) The drug is then tested on animals.
3) The drug is tested on healthy volunteers.
4) Further trials are carried out to establish the optimum dose for the drug.
5) The drug is then trialled with a sample of people who have the disease or condition to see if it is more effective than current treatments.
6) If all these tests are passed, the drug is then licensed for general use.

Question 26

HOW ARE MONOCLONAL ANTIBODIES PRODUCED?

Answer 26

1) lymphocytes are taken from a mouse
2) these are fused with tumour cells forming a hybridoma
3) Divides rapidly in lab conditions to form a clone
4) These clones are monoclonal antibodies

Question 27

WHAT ARE THE USES OF MONOCLONAL ANTIBODIES?

Answer 27

Diagnosis - used to detect Chlamydia, HIV and Plasmodium
Tissue typing - for transplants
Monitoring the spread of malaria - detect Plasmodium
Destroying cancer cells - act against tumour markers