Topic 2 Cells

Question 1

Active immunity

Answer 1

A type of immunity that develops when a person is exposed to microorganisms and foreign cells, the immune system responds.

Question 2

Passive immunity

Answer 2

A type of immunity which develops when one person’[s antibodies are transferred to another

Question 3

Explain the effect of antigen variability on disease and disease prevention

Answer 3

Antigens on pathogens change shape due to gene mutations
So no longer immune from vaccine
B memory cells receptors cannnot recognise changed antigen on secondary exposure
Specific antibodies no longer complementary to changed antigen

Question 4

Explain why antibiotics are ineffective against viruses

Answer 4

Viruses do not have the structures that antibiotics inhibit
As viruses do not have metabolic processes
Viruses do not have more in cell wall

Question 5

Why are viruses described as acellular and non-living

Answer 5

Acellular: not made of cells, no cell membrane, cytoplasm or organelles
Non-living: have no metabolism, cannot independently function