11.1 Flashcards
What is a pathogen? (1)
a disease-causing microorganism
What is a disease? (2)
(1) it’s the malfunction of the body or mind
(2) that has an adverse effect on good health
What must the microorganism do to be considered a pathogen? (4)
(1) gain entry to the host
(2) colonise the tissues of the host
(3) resist the defences of the host
(4) cause damage to the host’s tissues
When does a disease occur? (1)
when an infection leads to recognisable symptoms in the host
What is transmission? (1)
When a pathogen is transferred from one individual to another.
How does an infection occur? (2)
(1) when a pathogen gets into the host
(2) and colonises its tissue
What is an interface? (2)
(1) a surface or a boundary
(2) that links 2 systems (internal & external env)
How can an invasion by pathogens occur in the body? (1)
when the skin / interface / barrier is broken
How have interfaces of the body evolved to allow exchange of material between the internal & external environments? (4)
(1) they are thin
(2) moist
(3) large surface area
(4) good blood supply
Specific features of interfaces make easy entry for molecules as well as pathogens.
Which systems can pathogens enter through these interfaces? (3)
(1) gas-exchange system
(2) digestive system
(3) reproductive system
What natural defences does the body have that helps it prevent the entry of pathogens? Explain each (6)
(1) a mucus layer that covers gas exchange surfaces. —> (4) it forms a thick, sticky barrier that’s difficult to penetrate
(2) production of enzymes —> (5) it breaks down the pathogens
(3) production of stomach acid —> (6) it kills microorganism
Describe the 2 ways that pathogens affect the body. (2)
(1) it damages host tissues
(2) it produces toxins
How quickly a pathogen causes damage is related to… (1)
how rapidly the pathogen divides
“Putting bee honey on a cut kills bacteria. Honey contains a high conc of sugar.
Use your knowledge of water potential to suggest how putting honey on a cut kills bacteria.” (3)
(1) water potential in cells higher
(2) water leaves cells by osmosis
(3) loss of water = stops metabolic reactions
Define validity. (2)
(1) suitability of the investigative procedure
(2) to answer the questions being asked
What is precision? (1)
measurements with little difference between them
What is reliability? (2)
(1) the investigation is repeatable
(2) by other scientists who get similar results
Why are the digestive & respiratory systems often the sites of entry for pathogens? (3)
(1) Diffusion takes place in these systems
(2) so they have a large SA, are thin, moist & have a good blood supply
(3) so pathogens can easily attach to & penetrate them
