Chapter 15 - Defense Against Diseases

Question 1

What is a pathogen?

Answer 1

Any organism (bacterium, virus, fungus or protozoan) that causes infectious diseases

Question 2

Define an antigen

Answer 2

Any foreign organism, pathogen or substance contains on the outer part a code called an antigen, which stimulates the production of antibodies

Question 3

Define an antibody

Answer 3

A specific protein molecule (immunoglobin) produced in reaction to antigens

Question 4

Define immunity

Answer 4

The state in which organisms are protected from the invasion of pathogens which mainly involves the production of antibodies

Question 5

Define an epidemic and a pandemic

Answer 5

An infectious disease which spreads very quickly and affects many people in a certain area. A pandemic is a worldwide epidemic

Question 6

How are non-transmittable diseases like albinism and single cell anaemia caused

Answer 6

Genetic disorders (faulty genes and chromosomes)

Question 7

How are non-transmittable diseases like rickets and scurvy caused?

Answer 7

Nutritional deficiency diseases: Not eating a balanced diet

Question 8

How are non-transmittable diseases like like paralysis and skin cancer caused?

Answer 8

• Accidents

- Carcinogens (substance capable of causing cancer in living tissue)

Question 9

Name the disease caused by a bacterium which is transmitted by water

Answer 9

Cholera

Question 10

Name the pathogen and method of transmission of AIDS

Answer 10

• Virus

- Sexual contact or blood transfusion or infected needles

Question 11

Name the pathogen and mode of transmission of malaria

Answer 11

• Protozoa (Plasmodium)

- Insect bite (insect to human)

Question 12

Name the disease which is caused by bacteria and transmitted by sexual contact

Answer 12

Gonorrhoea

Question 13

Name the pathogen and mode of transmission of measles

Answer 13

• Virus

- Air droplets (coughing and sneezing)

Question 14

Name the pathogen and mode of transmission of rabies

Answer 14

• Virus

- Animal bite (contact with infected animal’s saliva)

Question 15

Name the mode of transmission and the pathogen associated with tuberculosis

Answer 15

• Air droplets (inhaling of droplets)

- Bacteria

Question 16

Name the mode of transmission and the pathogen associated with athletes foot

Answer 16

• Contact with objects (like in communal showers)

- Fungus

Question 17

Name the mode of transmission and the pathogen associated with common colds and flu

Answer 17

• Air droplets (inhaling of droplets)

- Virus

Question 18

Name the mode of transmission and the pathogen associated with syphillis

Answer 18

• Sexual contact

- Bacteria

Question 19

Name the modes of transmission and the pathogen associated with meningitis

Answer 19

• Air (inhaling, coughing, sneezing)
• Direct contact
• Bacteria or virus

Question 20

Name the mode of transmission and the pathogen associated with ringworm

Answer 20

• Direct contact (animal-human or human-human)

- Fungus (NOT A WORM)

Question 21

Name the mode of transmission and the pathogen associated with a sore throat

Answer 21

• Air (inhaling)

- Bacteria

Question 22

Describe the entire immune response

Answer 22

• When a pathogen enters the body, the bone marrow starts producing lymphocytes
• The lymphocytes mature in the thynus gland
• Lymphocytes move to lymph nodes
• Lymphocytes come in contact with pathogens and form plasma cells
• Plasma cells read antigens on the pathogen and forms an antigen-antibody complex
• The pathogen is then deactivated
• Deactivated pathogens are engulfed and digested by neutrophills

Question 23

Describe immunity

Answer 23

• Some plasma cells return to the lymph nodes as memory cells
• When the pathogen enters again, these memory cells “remember” the antigen
• Antibodies can be produced before symptoms start to show
• This is called immunity

Question 24

Define an infectious disease

Answer 24

A disease caused by pathogens (virusses and certain bacteria) which can be passed on from one individual to another