Unit 3 - Infection & Response Flashcards
What is a communicable disease?
A disease caused by a pathogen which can
be passed between animals or plants eg. flu.
What is a pathogen?
A disease-causing microorganism e.g.
bacteria
How do bacteria cause disease?
Once inside the body, they divide rapidly by
binary fission. They kill cells and produce
harmful toxins.
How do viruses cause disease?
They invade and reproduce inside living
body cells, leading to cell damage.
Give three ways in which pathogens can be spread
● By air - flu, tuberculosis and the common cold are
spread by droplet infection.
● By water - fungal spores in water spread plant
diseases.
● By direct contact - common in plant diseases and
sexually transmitted infections.
Give four ways in which the spread of pathogens
can be reduced
● Hygiene - handwashing, disinfectants, tissues.
● Reducing contact with infected individuals -
quarantine.
● Removing vectors - use of pesticides and
insecticides, removal of habitats.
● Vaccination.
Why is it especially important to prevent the spread
of viral diseases?
Scientists have not yet developed cures for
many viral diseases.
What is measles?
Measles is a serious viral disease that can
cause blindness and brain damage. The
main symptoms are a fever and a red skin
rash.
How is measles spread?
By air - through the inhalation of droplets
from coughs and sneezes
What is HIV/AIDS?
HIV is a virus which attacks and damages the
immune system until it can no longer function
properly. AIDS is the condition resulting from a
long-term HIV infection. There is no cure or
vaccine for HIV/AIDS.
How is HIV spread?
Direct sexual contact and the exchange
of bodily fluids eg. blood, breastmilk.
How can the spread of HIV/AIDS be prevented?
● Use of condoms
● Screening of blood for transfusions
● Not sharing needles
● Bottle-feeding by HIV-positive mothers
● Use of antiretroviral drugs to prevent the
development of AIDS
What is tobacco mosaic virus?
A plant pathogen which causes leaf discolouration
when cells are damaged. Affected areas cannot
photosynthesise, reducing the crop yield. As there is
no treatment, farmers grow TMV-resistant crop
strains to avoid infection.
How is tobacco mosaic virus spread?
Contact between infected and healthy plants.
Insects may act as vectors which transfer the
virus between different plants.
What is salmonella?
A type of bacteria found in raw meat, poultry
and eggs. If they enter the body via food
poisoning, they can affect natural gut
bacteria.
What are the symptoms of salmonella food poisoning?
● Fever
● Abdominal cramping
● Vomiting
● Diarrhoea
May be fatal in very young or elderly populations due the
risk of dehydration.
How can the spread of salmonella be limited?
● Vaccinating animals intended for consumption
● Keep raw meat away from cooked meat
● Disinfect hands and surfaces after contact with
raw meat
● Thoroughly cook meat
What is gonorrhoea?
A sexually transmitted bacterial infection caused by
unprotected sex with an infected individual. Early symptoms
include yellow/green discharge from genitals and painful
urination, although it may be symptomless.
Its spread can be controlled through the use of antibiotics (no
longer penicillin as many strains are resistant) and using
condoms.
What is rose black spot?
A fungal disease which causes purple or black
spots to develop on rose leaves. It reduces the
area of the leaf which is available for
photosynthesis and causes leaves to turn yellow
and drop prematurely.
How is the rose black spot fungus spread?
Fungal spores are spread by the wind
and in water.
How can the rose black spot fungus be treated?
● Using fungicides
● Destroying infected leaves
What is malaria?
Malaria is a disease caused by protist pathogens.
The disease is carried from host to host by
mosquitoes, and the protists enter the human
bloodstream when they feed. Symptoms include
fever and shaking, and it may also be fatal in some
cases.
