Chapter 10

Question 1

What is a Pathogen?

Answer 1

A pathogen is a disease causing organism.

Question 2

What is a transmissable disease?

Answer 2

It is a disease in which a pathogen passes from one host to another.

Question 3

How are Pathogens transmitted?

Answer 3

By Direct contact - Blood and body fluids
By Indirect contact- Contaminated surfaces, food, water, air.

Question 4

What are the Bodys defences?

Answer 4

• Skin: Physical barrier prevents pathogens from entering the body.
• Hairs in nose: Nose hairs act as a natural filter, trapping dust and pathogens from entering the lungs.
• Mucus: Sticky substance traps pathogens before entering lungs.
• Stomach acid: HCL kills pathogens consumed with food.
• WBCs: Carry out Phagocytosis + Antibody production.

Question 5

How can we control spread of disease?

Answer 5

• Good water supply (diseases caused otherwise are cholera, Diarrhoea, dysentery, typhoid)
• Hygienic food preparation
• Personal hygiene
• Waste disposal
• Sewage treatment

Question 6

What is Active immunity?

Answer 6

It is defense against a pathogen by antibody production.
- It is gained after infection or by Vaccination
- Lymphocytes also produce MEMORY CELLS that remain in blood even after an infection is over.
- These can quickly produce original antibodies if the same pathogen came again.
- This is long-term immunity.

Question 7

What are Antigens?

Answer 7

Antigens are a unique marker shape on the surface of membranes of Pathogens.
Antigens have a specific shape.

Question 8

What is the function of Antibodies on Antigens?

Answer 8

Lymphocytes produce proteins called Antibodies which are complementary to the Antigen of Pathogens.
- Antibodies bind to Antigens of Pathogens, destroying them or marking them for Phagocytes.

Question 9

What is Vaccination?

Answer 9

It is a way of protecting the body against harmful diseases.

Question 10

What is the process of Vaccination?

Answer 10

• Weakened pathogens or antigens are put into the body.
• The antigens stimulate immune response from lymphocytes which produce Antibodies.
• Antibodies produce memory cells which give long-term immunity.

Question 11

What is a Vaccine and its types?

Answer 11

Its what is injected/swallowed:
- A harmless form of micro-organism ex: BCG inoculation/Sabin Oral vaccine
- The killed micro-organism ex: Salk anti-polio vaccine
- A toxoid: The inactivated toxin produced by bacteria.

Question 12

What is Passive immunity?

Answer 12

Its short-term defense against pathogens by Antibodies obtained from another individual:
- From mothers blood
- Breast milk
There is NO FORMATION OF MEMORY CELLS.

Question 13

What is Cholera?

Answer 13

It is a disease caused by bacterium transmitted in contaminated water.
- It causes Diarrhoea.

Question 14

What is the process of Cholera?

Answer 14

• Cholera is caused when bacteria invade the wall of the small intenstine.
• Here they rapidly reproduce and produce a toxin.
• The toxin causes cells in the intestine to secrete Chloride ions
• This causes the water potential in small intestine to decrease
• As a result, water from cells in intestine lining move into the small intestine by Osmosis.
• Large amounts of water is lost from the body; causing Dehydration