Disease and Immunity 17/04.

Question 1

What is a pathogen?

Answer 1

A pathogen is a disease causing organism.

Question 2

What is a transmissible disease?

Answer 2

A transmissible disease is a disease in which the pathogen can be passed from one host to another.

Question 3

What are the two ways in which a pathogen is transmitted?

Answer 3

• By direct contact, including through blood and other body fluids.
• Indirectly, including from contaminated surfaces, animals and air.

Question 4

What are 5 body defenses?

Answer 4

• Skin.
• Hairs in the nose.
• Mucus.
• Stomach acid.
• White blood cells.

Question 5

What are the 5 important factors in controlling the spread of disease?

Answer 5

• A clean water supply.
• Hygenic food preparation.
• Good personal hygiene.
• Waste disposal.
• Sewage treatment.

Question 6

What is active immunity?

Answer 6

Active immunity as defence against a pathogen by antibody production in the body.

Question 7

Fill in the missing spaces:
Each pathogen has its own ______, which have ______ _____.

Answer 7

Each pathogen has its own antigens, which have specific shapes.

Question 8

What are antibodies?

Answer 8

Antibodies are proteins that bind to antigens leading to the direct destruction of pathogens or marking of pathogens for destruction by phagocytes.

Question 9

Fill in the missing spaces:
Specific antibodies have ________ ______ which fit specific _______.

Answer 9

Specific antibodies have complementary shapes which fit specific antigens.

Question 10

How is active immunity gained?

Answer 10

Active immunity is gained after an infection by a pathogen or by vaccination.

Question 11

What are the three processes of vaccination?

Answer 11

• Weaked pathogen or their antigens are put into the body.
• The antigens stimulate an immune response by lymphocytes which produce antibodies.
• Memory cells are produced that give long-term immunity.

Question 12

What is passive immunity?

Answer 12

Passive immunity is a short-term defense against a pathogen by antibodies acquired from another individual, including across the placenta and in breast milk.

Question 13

Are memory cells produced in passive immunity?

Answer 13

Memory cells are not produced in passive immunity.

Question 14

Are memory cells produced in passive immunity?

Answer 14

Memory cells are not produced in passive immunity.

Question 15

What is cholera?

Answer 15

Cholera is a disease caused by a bacterium which is transmitted in contaminated water.

Question 16

What does cholera bacterium produces and what is the effect of this?

Answer 16

Cholera bacterium produces a toxin that causes secretion of chloride ions into the small intestine causing osmotic movement of water into the gut, causing diarrhoea, dehyradration and loss of ions from the blood.

Question 17

Explain the role of vaccination in controlling the spread of diseases.

Answer 17

If a large enough percentage of the population is vaccinated, it provides protection for the entire population because there are very few places for the pathogen to breed - this is known as herd immunity.

Question 18

Explain the importance of breast-feeding for the development of passive immunity in infants.

Answer 18

Antibodies pass from mother to infant via breast milk - this is important as it helps the very young to fight off infections until they are older and stronger and their immune system is more responsive.