Module 4 – Biodiversity, Evolution and
disease
4.1.1 Communicable diseases, disease prevention and
the immune system
(a) the different types of pathogen that can cause communicable diseases in
plants and animals
Types of pathogen:
Pathogen: a microorganism that causes disease
Bacteria – damage cells or release waste products/toxins. Often live in vascular tissue of plants
causing blackening and death of these tissues
Disease Pathogen Details of disease
Tuberculosis Mycobacterium tuberculosis Kills cells and tissues, often affecting lungs
and M. bovis
Bacterial meningitis Neisseria meningitidis or Infection of the meninges (membranes
Streptococcus pneumonia that surround the brain and spinal cord);
membranes become swollen and may
cause damage to brain and nerves
Ring rot (plants) Clavibacter michiganensis Ring of decay in the vascular tissue of a
potato tuber/tomato and leaves wilt
Viruses – invade cells and take over genetic machinery and organelles to reproduce inside cells
until the cell bursts and new viruses are released to infect other cells
HIV/AIDS Human immunodeficiency Attacks cells in the immune system,
virus compromising immune response
Influenza Orthomyxoviridae family Attacks respiratory system and causes
muscle pains and headaches
Tobacco mosaic virus Tobacco mosaic virus Causes mottling and discolouration of
(plants) leaves
Protoctista – enter host cells and feed on the contents as they grow e.g. malaria feeds on
haemoglobin
Malaria Plasmodium falciparum, Parasite in blood that causes headache
P.vivax, P.ovale, P.malariae and fever. May progress to coma / death
Blight (tomatoes and Phytophthora infestans Affects both leaves and potato tubers
potatoes)
Fungi –mycelium grows under the skin surface and send out reproductive hyphae which grow
to the skin and release spores, causing redness and irritation. Often live in vascular tissue of
plants where they can gain nutrients; hyphae release enzymes to digest cellulase, causing decay.
Athlete’s foot Trichophyton rubrum Growth under skin of feet – particularly
between toes
Ringworm (cattle) Trichophyton verrucosum Growth of fungus in skin with spore
cases erupting through to cause a rash
Black sigatoka Mycosphaerella fijiensis Causes leaf spots on banana plants,
(bananas) reducing yield
disease
4.1.1 Communicable diseases, disease prevention and
the immune system
(a) the different types of pathogen that can cause communicable diseases in
plants and animals
Types of pathogen:
Pathogen: a microorganism that causes disease
Bacteria – damage cells or release waste products/toxins. Often live in vascular tissue of plants
causing blackening and death of these tissues
Disease Pathogen Details of disease
Tuberculosis Mycobacterium tuberculosis Kills cells and tissues, often affecting lungs
and M. bovis
Bacterial meningitis Neisseria meningitidis or Infection of the meninges (membranes
Streptococcus pneumonia that surround the brain and spinal cord);
membranes become swollen and may
cause damage to brain and nerves
Ring rot (plants) Clavibacter michiganensis Ring of decay in the vascular tissue of a
potato tuber/tomato and leaves wilt
Viruses – invade cells and take over genetic machinery and organelles to reproduce inside cells
until the cell bursts and new viruses are released to infect other cells
HIV/AIDS Human immunodeficiency Attacks cells in the immune system,
virus compromising immune response
Influenza Orthomyxoviridae family Attacks respiratory system and causes
muscle pains and headaches
Tobacco mosaic virus Tobacco mosaic virus Causes mottling and discolouration of
(plants) leaves
Protoctista – enter host cells and feed on the contents as they grow e.g. malaria feeds on
haemoglobin
Malaria Plasmodium falciparum, Parasite in blood that causes headache
P.vivax, P.ovale, P.malariae and fever. May progress to coma / death
Blight (tomatoes and Phytophthora infestans Affects both leaves and potato tubers
potatoes)
Fungi –mycelium grows under the skin surface and send out reproductive hyphae which grow
to the skin and release spores, causing redness and irritation. Often live in vascular tissue of
plants where they can gain nutrients; hyphae release enzymes to digest cellulase, causing decay.
Athlete’s foot Trichophyton rubrum Growth under skin of feet – particularly
between toes
Ringworm (cattle) Trichophyton verrucosum Growth of fungus in skin with spore
cases erupting through to cause a rash
Black sigatoka Mycosphaerella fijiensis Causes leaf spots on banana plants,
(bananas) reducing yield
