4.1.1 communicable diseases Flashcards
are bacteria prokaryotes or eukaryotes
4.1.1(a)
prokaryotes
do bacteria have a cell wall
4.1.1(a)
yes
do bacterial cells have membrane bound organelles
4.1.1(a)
no
what are the 3 diseases caused by bacteria and where are they found
4.1.1(a)
tuberculosis-animals
bacterial meningitis-animals
ring rot-plans
what do viruses consist of
4.1.1(a)
short section of DNA or RNA surrounded by a protein coat (Caspid)
do viruses contain any membrane bound organelles
4.1.1(a)
no
do viruses contain a cell wall
4.1.1(a)
no
what are the three disease caused by viruses and where are they found
4.1.1(a)
HIV/AIDS-animals
influenza-animals
tobacco mosaic virus-plants
how do protists carry diseases
4.1.1(a)
through a vector
what are two diseases caused by protists and where are they found
4.1.1(a)
malaria-animals
potato blight-plant
do fungi have a cell wall
4.1.1(a)
yes
do fungi have membrane bound organelles
4.1.1(a)
yes
what are the 3 diseases caused by fungi and where are they found
4.1.1(a)
athletes foot-animals
ringworm-animals
black sigatoka-plants
what is direct transmission
4.1.1(b)
This occurs when the pathogen is transferred directly from one infected individual to another susceptible individual
what are the 4 types of direct transmission
4.1.1(b)
-direct contact
-inoculation
-transmission between animals and humans
-indigestion
what is direct contact
(direct transmission)
4.1.1(b)
Kissing or any contact with the bodily fluids of another person
Direct skin-to-skin contact e.g. ringworm, athlete’s foot
Microorganisms from faeces transmitted on the hands
what is inoculation
(direct transmission)
4.1.1(b)
Bodily fluids transmitted through a break in the skin, into the blood:
· during sex (e.g. HIV)
· from an animal bite (e.g. rabies)
· through a puncture wound or through sharing needles (e.g. hepatitis B
what is transmission between humans and animals
(direct transmission)
4.1.1(b)
Some communicable diseases can be passed from animals to people. These are known as zoonotic disease
what is indigestion
(direct transmission)
4.1.1(b)
Taking in contaminated food or drink
or transferring pathogens to the mouth from the hand
what is indirect transmission
4.1.1(b)
Occurs when a pathogen travels from one individual to another indirectly. Contact with the infected individual is not necessary.
what are the two types of indirect transmission
4.1.1(b)
-fomites
-inhaling droplets
what are fomites
(indirect transmission)
4.1.1(b)
Inanimate objects such as bedding, socks or cosmetics can transfer pathogens, for example the fungus that causes athlete’s foot can be transferred from a surface infected by fungal spores.
what is inhaling droplets
(indirect transmission)
4.1.1(b)
Tiny droplets of saliva and mucus are expelled from your mouth as you talk, cough or sneeze. If these droplets contain pathogens, healthy individuals can breathe them in and become infected.
what is a vector
4.1.1(b)
A vector is (usually) an organism that transmits communicable pathogens from one host to another.
4 factor affecting the transmission of communicable disease in animals
4.1.1(b)
Overcrowded living and working conditions make it easier for diseases to spread, and poor sanitation means that it is easier for pathogens to spread through dirty water.
People may have compromised immune systems due to other conditions like AIDS, or due to immunosuppressant drugs. Being malnourished makes it more difficult for the immune system to respond effectively to pathogens.
Climate change can introduce vectors and diseases to areas that would not historically have had them. For example, increasing temperatures promote the spread of malaria as it increases the geographical area that is suitable habitat for Anopheles mosquitos.
Socioeconomic factors can influence the distribution of trained healthcare workers and the ease of spreading information about how to prevent the spread of disease, as well as communicating about outbreaks and delivering treatments or vaccines.
how does direct transmission occur in plants
4.1.1(b)
Plant pathogens can spread by direct contact between a healthy plant and any part of a diseased plant
how does indirect transmission occur in plants
4.1.1(b)
infected plants leave pathogens or reproductive spores in the soil these can then infect the next plant
what are the 4 vectors in plants that can cause diseases
4.1.1(b)
Wind – bacteria, viruses and fungal or oomycete spores can be carried on the wind, e.g. P. infestans sporangia form spores that are carried by the wind to other potato crops
Water – raindrop splashes can carry pathogens and spores from one plant to another
Animals – insects and birds carry pathogens and spores from one plant to another as they feed. Insects like aphids inoculate pathogens directly into plant tissues
Humans – pathogens and spores are transmitted by hands, clothing, fomites, farming practices, and by transporting plants and crops around the world.
what are the factors affecting the transmission of communicable diseases in plants
4.1.1(b)
· Planting of varieties that are susceptible to disease – most crop plants have been selectively bred leading to very low genetic diversity, so all of the plants in a monoculture will be susceptible to diseases
· Over-crowding in fields increases likelihood of direct contact
· Poor mineral ion content in soils reduces resistance of plants
· Damp, warm conditions increase survival and spread of pathogens and spores
· Climate change – increased rainfall and wind promote the spread of pathogens; changing conditions allow animal vectors to spread to new areas; drier conditions may reduce the spread of pathogens
what do plant cell wall receptor bind to/respond to
4.1.1(c)
1.plant cell wall receptors bind to antigens on the pathogen
- this stimulates the release of signalling molecules that increase the transcription of defence genes
3.this triggers a cellular response eg-producing defence chemicals + physically strengthening there cell walls
what can these chemicals produced by plants do
4.1.1(c)
repel insect vectors
kill invading pathogens
what are the chemicals that plants use for defense used as
4.1.1(c)
-human medicines
-others have strong flavour and can be used as herbs, spices
what are examples of some of the chemicals produced by the plants
4.1.1(c)
-insect repellents
-insecticides
-antibacterial + antifungal compounds
what are some physical defenses plants have
4.1.1(c)
-leaves have a waxy impermeable cuticle acts as a physical barrier also prevents water from collecting on the leaf which could transmit pathogens
-trees have thick bark
-plant cells have cellulose cell walls that act as physical barriers
after an initial attack by a pathogen what is deposited
4.1.1(c)
callose is synthesized and deposited
where is callose deposited
4.1.1(c)
-between cell wall and cell membrane
-cell membranes in cells next to the infected cells
-in sieve plates in the phloem
-in plasmodestmata
after callose is deposited what is deposited next
4.1.1(c)
lignin
this makes the mechanical barrier thicker and stronger
why is callose deposited in sieve plates and plasmodestmata
4.1.1(c)
to seal off infected part from neighboring cells and prevent pathogens from spreading
what is callose and what is it joined by
4.1.1(c)
Callose is a polysaccharide made of glucose joined together by β-1,3 glycosidic bond
if pathogens are detected on leaf surface what may guard cells do
4.1.1(c)
if pathogens are detected on leaf surface guard cells may close stomata to prevent entry
what do plants do to infected leafs
4.1.1(c)
plants can drop infected leafs through the process of leaf abscission
what is the primary non-specific defence
4.1.1(d)
defends against all pathogens in the same way and is always present.
what does skin prevent the entry of pathogens
4.1.1(d)
-its a impermeable barrier
-its covered in a skin flora of healthy microorganisms that
outcompete pathogens for space on the body surface
-secretes sebum-which inhibits pathogen growth. It also seals off hair follicles to prevent pathogen entry
when platelets contact collagen in the skin or in the walls of damaged blood vessels what 2 products are secreted
4.1.1(d)
thromboplastin
seratonin