Topic 3: Infection and response

Question 1

Types of organisms defend themselves against microorganisms

Answer 1

animals:
skin- oils to kill microbes
nose-hairs keep out dust and microbes
trachea/bronchi-mucus traps microbes/cilia moves mucus
stomach- HCL kills bacteria
white blood cells-produce antibodies/antitoxins

Question 2

plants

Answer 2

cell wall- tough to penetrate
waxy cuticle- tough to penetrate
dead cells/bark-fall off taking pathogen with him
production of antibacterial chemicals- kill bacteria

Question 3

fungi

Answer 3

antibiotic production- kill bacteria

Question 4

Explain why plants with TMV have stunted growth

Answer 4

• less photosynthesis because lack of chlorophyll
• less glucose made so less energy for growth
  -glucose needed for respiration

Question 5

Drugs must be trialled before the drugs can be used on patients

Answer 5

• toxicity
  -dosage
  -efficacy

Question 6

Describe how pathogens cause infections and how the immune system defends the body against these pathogens

Answer 6

• bacteria and viruses are pathogens
  -they reproduce rapidly inside the body
  -bacteria may produce toxins
  -viruses live inside cells
  white blood cells help to defend against pathogens by
  -ingesting pathogens to destroy pathogen
  -producing antibodies/antitoxins
  -to counteract toxins
  -leads to immunity from that pathogen

Question 7

Explain how a vaccination can prevent an illness

Answer 7

-dead/inactive pathogen injected into the body
-white blood cells respond by producing antibodies
-antibodies are specific to pathogen and produce quick response
-in larger quantities killing pathogen

Question 8

Explain how a pregnancy test strip works to show a positive result

Answer 8

-as urine passes through reaction zone
-HCG hormone binds to the mobile HCG antibody
-HCG hormone binds to the immobilised HCG antibodies in the results zone
-antibodies which did not attach to HGC
bind to antibodies in control zone
-blue dye appears in both control and results zone