COMMUNICABLE DISEASES, DISEASE PREVENTION AND THE IMMUNE SYSTEM
(a) The different types of pathogen that can cause communicable diseases in plants
and animals.
● To include,
○ Bacteria – tuberculosis (TB), bacterial meningitis, ring rot (potatoes,
tomatoes).
○ Virus – HIV/AIDS (human), influenza (animals), Tobacco Mosaic Virus
(plants).
○ Protoctista – malaria, potato/tomato late blight.
○ Fungi – black sigatoka (bananas), ring worm (cattle), athlete’s foot
(humans).
Communicable disease are caused by infective organisms, pathogens which are any
microorganism that causes disease. Pathogens include viruses and many bacteria,
fungi and protozoans. The organisms in which pathogens live is the host and these
provide a good habitat in which microorganisms can live. As a result, there are
numerous types of microorganism that live in or on the body of another organism.
Pathogens live by taking nutrition from their host, but also cause damage in the
process. This damage can be considerable.
Firstly, bacteria are the most ubiquitous microorganism, some of which are
pathogens and, therefore, responsible for the transmission of disease. They are
unicellular organisms that lack a distinct nuclear membrane and has a cell wall of
unique composition. Their cells are smaller than eukaryotic cells, but they can
reproduce rapidly, by binary fission. In the right conditions, some types of bacteria
can reproduce every 20 minutes. Once in the host body, they can multiply rapidly.
Their presence can cause disease by damaging cells or by releasing waste products
and/or toxins that are toxic to the host. In plants, the bacteria of these tissues.
Fungi can also cause a variety of diseases in both plants and animals. There
are common fungal infections where the fungus lives in the skin of an animal, and
where its hyphae, which form a mycelium, grow under the skin surface. The fungus
can send out specialised reproductive hyphae, which grow to the surface of the skin
to release spores. This causes redness and irritation. In plants, the fungus often lives
in the vascular tissue, where it can gain nutrients. The hyphae release extracellular
enzymes, such as cellulases, to digest the surrounding tissues, which causes decay.
Leaves will often become mottled in colour, curl up and shrivel, before dying. Fruit
and storage organs, such as tubers (potatoes), will turn black and decay.
Then, there are viruses, which cause many well-known diseases in both plants
and animals, such as HIV. Viruses invade cells and take over the genetic machinery
and other organelles or the cell. They then cause the cell to manufacture more copies
of the virus. The host cell eventually bursts, releasing many new viruses which will
infect healthy cells.
There are also a, smaller, number of diseases caused by animal-like protoctists.
These organisms usually cause harm by entering host cells and feeding on the
contents as they grow. The malarial parasite Plasmodium has immature forms that
feed on the haemoglobin inside red blood cells.
(a) The different types of pathogen that can cause communicable diseases in plants
and animals.
● To include,
○ Bacteria – tuberculosis (TB), bacterial meningitis, ring rot (potatoes,
tomatoes).
○ Virus – HIV/AIDS (human), influenza (animals), Tobacco Mosaic Virus
(plants).
○ Protoctista – malaria, potato/tomato late blight.
○ Fungi – black sigatoka (bananas), ring worm (cattle), athlete’s foot
(humans).
Communicable disease are caused by infective organisms, pathogens which are any
microorganism that causes disease. Pathogens include viruses and many bacteria,
fungi and protozoans. The organisms in which pathogens live is the host and these
provide a good habitat in which microorganisms can live. As a result, there are
numerous types of microorganism that live in or on the body of another organism.
Pathogens live by taking nutrition from their host, but also cause damage in the
process. This damage can be considerable.
Firstly, bacteria are the most ubiquitous microorganism, some of which are
pathogens and, therefore, responsible for the transmission of disease. They are
unicellular organisms that lack a distinct nuclear membrane and has a cell wall of
unique composition. Their cells are smaller than eukaryotic cells, but they can
reproduce rapidly, by binary fission. In the right conditions, some types of bacteria
can reproduce every 20 minutes. Once in the host body, they can multiply rapidly.
Their presence can cause disease by damaging cells or by releasing waste products
and/or toxins that are toxic to the host. In plants, the bacteria of these tissues.
Fungi can also cause a variety of diseases in both plants and animals. There
are common fungal infections where the fungus lives in the skin of an animal, and
where its hyphae, which form a mycelium, grow under the skin surface. The fungus
can send out specialised reproductive hyphae, which grow to the surface of the skin
to release spores. This causes redness and irritation. In plants, the fungus often lives
in the vascular tissue, where it can gain nutrients. The hyphae release extracellular
enzymes, such as cellulases, to digest the surrounding tissues, which causes decay.
Leaves will often become mottled in colour, curl up and shrivel, before dying. Fruit
and storage organs, such as tubers (potatoes), will turn black and decay.
Then, there are viruses, which cause many well-known diseases in both plants
and animals, such as HIV. Viruses invade cells and take over the genetic machinery
and other organelles or the cell. They then cause the cell to manufacture more copies
of the virus. The host cell eventually bursts, releasing many new viruses which will
infect healthy cells.
There are also a, smaller, number of diseases caused by animal-like protoctists.
These organisms usually cause harm by entering host cells and feeding on the
contents as they grow. The malarial parasite Plasmodium has immature forms that
feed on the haemoglobin inside red blood cells.
