immunity

Question 1

describe how phagocytes and lysosomes are involved in destroying microorgansims

Answer 1

phagocytes engulf pathogen
enclose in a vesicle creating a phagosome
fuses with lysosome
lysosome enzymes hydrolyse molecule and break it down

Question 2

what is an antigen

Answer 2

protein that stimulates immune response

Question 3

what is an antibody

Answer 3

protein specific to an antigen to fit a complementary shape

Question 4

explain why antigen are protein molecules and why protein are well suited

Answer 4

large variety of different molecules
range of shapes
tertiary shape locks on to specific antigen

Question 5

how to vaccines protect people against disease

Answer 5

vaccines contain antigens
dead pathogens
stimulates production of memory cells
on second exposure memory cells produce antibodies that recognise pathogens
rapidly produce antibodies
antibodies destroy pathogens
herd immunity effect

Question 6

what is a vaccination

Answer 6

injection of antigens that are dead
stimulates formation of memory cells

Question 7

describe how memory cells protect the body from disease

Answer 7

on further exposure to the same microorganism
antigen recognised
fast response
greater production of antibodies

Question 8

what is a monoclonal antibody

Answer 8

hybrid cell from B lymphocyte
antibodies the same from one type of plasma cell specific to one antigen

Question 9

suggest problems for patient when using vaccines

Answer 9

process of killing organisms might not be 100% efficient
attenuated organisms are non-virulent but might mutate to virulent forms
immunity can decline and require booster injections
side effects

Question 10

suggest two reasons why parents may decide against vaccination for their children

Answer 10

consider vaccines to be unsafe because of side effects or damage to immune system
consider natural immunity more effective
ethical objections for the use of animal tissue
low risk of disease when high percentage of population already vaccinated- herd immunity

Question 11

explain how the defence mechanisms of the body reduce the change of entry by a pathogen

Answer 11

mucus traps sticky pathogens
tears, saliva and mucus contain lysozyme breaking down bacterial cell wall
stomach contains HCL which destroys bacteria

Question 12

role of B lymphocytes and T lymphocytes in defence of the body against a virus infection

Answer 12

B lymphocytes produce antibodies (humoral response)
T lymphocytes involved in cell mediated immunity
macrophages present antigens
B lymphocytes recognise antigen
produce plasma cells which make antibody
antibodies bind and clump to virus
memory cells produced by first exposure and cloned on second exposure
T lymphocytes produce chemicals which aid B lymphocyte cloning
encourages phagocytes to engulf clumped virus
killer T cells kill virus infected cells