Chapter 12- Communicable Diseases

Question 1

Define parasite

Answer 1

-live in host + gain nutrition from host + harm host

Protist which causes disease

Question 2

Why human body’s primary defences do not prevent entry of mosquitos which carry parasite for malaria?

Answer 2

• mosquitoes feed on blood

- to do this they break skin + thus skin cannot act as a barrier

Question 3

Why malaria much more common in tropical areas?

Answer 3

-suitable temperature for mosquitoes

Question 4

Why governments in parts of the world other than tropical areas are concerned about malaria?

Answer 4

• global warming may result in spread to other parts of the world
• resistance of parasite to drugs
• resistance of mosquitoes to insecticides

Question 5

Why erythrocytes that contain ___ are more likely to be destroyed by phagocytosis than healthy erythrocytes?

Answer 5

-infected erythrocytes release chemicals that attract phagocytes

Question 6

How structure of antibodies allows them to perform their function?

Answer 6

• 4 polypeptide chain consisting of 2 light + 2 heavy chains -variable region allows binding to antigen
• 2 variable regions allow binding of more than 1 antigen
• different variable regions on antibodies allows specificity to different antigens
• hinge allows flexibility
• disulfide bridges hold polypeptide chains together

Question 7

‘Bacteria are now immune to antibiotics’ why is use of immune wrong?

Answer 7

• immunity involves WBC which bacteria don’t have
• correct term is resistant
• bacteria is unicellular. Only multicellular organisms can have an immune response

Question 8

Why are phagocytes described as secondary defence?

Answer 8

-involved after pathogen has entered the body

Question 9

Why response involving phagocytes regarded as non specific?

Answer 9

-phagocytes can break down many different pathogens

Question 10

How phagocytes are able to pass from blood to tissue fluid?

Answer 10

• can move between the cells in the walls of capillaries

- have flexible structures

Question 11

How pathogen is destroyed after it has become attached to surface of phagocyte?

Answer 11

• pathogen engulfed by cytoplasm to form phagosome by endocytosis
• lysosomes fuse with phagosome to form phagolysosome
• enzymes in lysosomes break down pathogens to amino acids + other substances
• break down products absorbed into cytoplasm
• unwanted products removed by exocytosis

Question 12

How antibodies defend body against pathogens by neutralisation?

Answer 12

-cover antigen on pathogen to prevent binding to host cell

Question 13

How antibodies defend body against pathogens by agglutination?

Answer 13

• clump together many pathogens so clump too large to cross membrane + enter host cell
• more can be consumed by phagocyte at once

Question 14

Infective agent that causes TB?

Answer 14

Mycobacterium

Question 15

How bacteria that causes TB is transmitted?

Answer 15

-droplets containing pathogens is released by sneezing or coughing which is inhaled by individual

Question 16

Why incidence of TB is higher in low income countries?

Answer 16

• poor diets
• overcrowded living spaces
• medical treatment more difficult to access
• more likely to consume milk or meat from infected cattle

Question 17

Which methods of pathogen transmission do not apply to plants?

Answer 17

• direct contact

- vectors

Question 18

Why vaccine has to be changed each year?

Answer 18

• diff strains of virus mutates each year
• new strain has diff antigens
• antibody produced needs to match new strain

Question 19

Role of memory cells when virus enters body?

Answer 19

• recognises antigen
• produces a clone
• changes to form plasma cells
• make antibodies
• destroy virus before symptoms appear

Question 20

How mosquito transmits malarial parasite to humans?

Answer 20

• mosquito is vector
• parasite present in saliva of mosquito
• mosquito feeds on human and parasite passes to blood

Question 21

What would graph for antibody conc look like in second infection?

Answer 21

• higher peak
• steeper initial increase
• conc at last day should be higher than peak for primary response

Question 22

Hinge region job?

Answer 22

Flexibility

Question 23

Constant region job?

Answer 23

Binding to phagocytes

Question 24

Variable region job?

Answer 24

Binding to antigens

Question 25

Why resistance to antibiotics is a concern?

Answer 25

- may become untreatable - potential for disease outbreak - developing new antibiotics is expensive

Question 26

Why influenza virus described as pathogen rather than parasite?

Answer 26

- pathogen causes disease - influenza virus causes disease - does not gain nutrients from host

Question 27

Plasma cells release antibodies. Outline role Of RNA in plasma cells.

Answer 27

- antibodies are proteins - DNA unable to leave nucleus - RNA is a copy of gene - RNA passes out of nucleus Through nuclear pore to ribosome for protein synthesis

Question 28

Use neutralisation to describe how antibodies reduce the threat from antibodies?

Answer 28

-cover binding site on pathogen to prevent antigen binding to host cell

Question 29

Use agglutination to describe how antibodies reduce the threat from antibodies?

Answer 29

- clump together many pathogens - clump too large to enter host cell - increased likelihood of being consumed by phagocyte

Question 30

Use opsonisation to describe how antibodies reduce the threat from antibodies?

Answer 30

- tag pathogens to increase recognition | - increased likelihood of being consumed by phagocyte

Question 31

Use lysins to describe how antibodies reduce the threat from antibodies?

Answer 31

- make lysins | - destroys pathogens

Question 32

Which groups should be vaccinated first and why?

Answer 32

- pregnant women. foetus has undeveloped immune system | - those with chronic diseases. Inability to withstand further disease

Question 33

Other than direct effects on health or reducing number of deaths, suggest reason why spending large amounts on vaccination is worth it?

Answer 33

- days lost at work affects economy | - health service unable to cope

Question 34

Why some people don’t want to get immunised?

Answer 34

- concerned about side effects | - too busy