Pathogens and communicable disease

Question 1

What is a disease?

Answer 1

A condition that impairs the normal functioning of an organism- in both plants and animals

Question 2

What is a pathogen?

Answer 2

An organism that causes disease. These include bacteria, viruses, fungi, and protoctista

Question 3

How are communicable diseases most commonly spread in animals?

Answer 3

From one species to another (intraspecific) but can also be spread between species (Inter specific)

Question 4

What are vectors?

Answer 4

Something that can carry pathogens from one organism to another. These include water and insects

Question 5

What is the first type of pathogen, bacteria?

Answer 5

-prokaryotes= no membrane bound organelles or nucleus
-only pathogenic bacteria will cause communicable disease

Question 6

What are the two ways in which bacteria can be classified?

Answer 6

1. By their basic shape
2. By being gram positive or gram negative to gram staining = the 2 different types of cell wall determine if an antibiotic is needed to kill the bacteria.

Question 7

Why is there a debate as to if viruses are alive or not?

Answer 7

-don’t fulfil the MRS GREN criteria, don’t have own metabolism, but do have genetic material which mutates causing new strains of virus to evolve

Question 8

What is the basic structure of a virus?

Answer 8

-Some genetic material (Either DNA or RNA) surrounded by a protein coat.
-around 50 times smaller then bacteria

Question 9

Why are viruses considered the ultimate parasites?

Answer 9

-they invade living cells and “hijack” the protein synthesis capability of the host cell, by inserting viral DNA into the genome , only allowing transcription and translation of viral genes

Question 10

What are retroviruses?

Answer 10

-viruses which have RNA as their genetic material= have to transcribe their RNA into DNA because it can’t be inserted into the DNA genome of the host cell . This requires the enzyme called reverse transcriptase

Question 11

What type of cells can viruses use as their host cell?

Answer 11

-all types of eukaryotes
-viruses called bacteriophages can also use prokaryotes

Question 12

What is the difference between protoctista and protista?

Answer 12

-protoctista= includes multicellular organisms
-protista= unicellular

Question 13

What are protoctista?

Answer 13

Group of eukaryotic organisms with a wide variety of feeding methods
-most are not pathogenic but those that are can cause communicable disease in both animals a and plants

Question 14

What is meant by pathogenic protoctista being parasitic?

Answer 14

-use the people or animals they infect as their host organism

Question 15

What are fungi?

Answer 15

-eukaryotic organisms, that are often multicellular, but if pathogenic are single celled

Question 16

Why do fungi feed on dead and decaying matter?

Answer 16

They have to digest food to obtain their nutrients, so they secrete digestive enzymes into the food source and absorb the nutrients

Question 17

What are parasitic fungi?

Answer 17

-feed of living plants and animals
-these ones cause communicable disease

Question 18

How does fungi pathogens kill plants?

Answer 18

They infect the plants which affects the leaves, stopping photosynthesis which kills the plant

Question 19

How have fungi adapted so they can spread rapidly and widely through crop plants?

Answer 19

-produce millions of tiny spores which can spread huge distances

Question 20

Give 4 ways in which pathogens can attack the cells of their host organism and cause disease?

Answer 20

1. Take over cell metabolism, as viral genetic material is inserted into host cell DNA
2. Take over cell and digest contents
3. Completely digest living cells and destroy them
4. Produce toxins which poison and damage host cells, some toxins break down cell membranes or inactivate enzymes or prevent cell division

Question 21

For the plant disease Ring rot, give the type of pathogen, name of pathogen, type of plants which are affected, and type of damage

Answer 21

• Type of pathogen: Bacteria

-Name of pathogen: Clavibacter michiganensis

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-Type of plant: Potatoes

-type of damage: to tubers- loss of edible crop

Question 22

For the plant disease Tobacco Mosaic virus, give the type of pathogen, name of pathogen, type of plants which are affected, and type of damage

Answer 22

-type of pathogen: virus

-name of pathogen: Tobacco mosaic virus

-type of plant: tobacco and 150 others e.g tomatoes

-type of damage: to leaves therefore reducing crop yield

Question 23

For the plant disease potato blight, give the type of pathogen, name of pathogen, type of plants which are affected, and type of damage

Answer 23

-type of pathogen: Protista

-name of pathogen: phytophthera infestans

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-type of plants: potatoes and tomatoes

-type of damage: to leaves, tubers and fruits

Question 24

For the plant disease Black Sigatoka, give the type of pathogen, name of pathogen, type of plants which are affected, and type of damage

Answer 24

-type of pathogen: fungus

-name of pathogen: mycosphaerrella fijiensis

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-type of plant: bananas

-type of damage: to leaves so fewer and smaller bananas grow

Question 25

Give an example of an animal diseases. State what it is caused by, how it is spread, and what increases the risk of catching it.

Answer 25

-Tuberculosis (TB)
-caused by Mycobacterium tuberculosis and mycobacterium bovis
-spread directly via droplet infection, and indirectly as can remain in air for long periods.
-risk of TB is increased when lots of people live crowded together