12.1 Animal & Plant Pathogens

Question 1

Types of Pathogens

Answer 1

Bacteria
Viruses
Protoctista (protista)
Fungi

Question 2

What is bacteria

Answer 2

They are prokaryotes; don’t have membrane-bound nucleus

Question 3

How can bacteria be classified

Answer 3

1. by their basic shapes

2. by their cell walls

Question 4

What are the shapes of bacteria

Answer 4

Rod shaped (bacilli)
Spherical (cocci)
Comma shaped (vibrios)
Spiralled (spirilla)
Corkscrew (sphirochaetes)

Question 5

What are the types of cell walls for bacteria

Answer 5

1. Gram positive bacteria
2. Gram negative bacteria

Each one is affected differently by antibiotics

Question 6

What is Gram +

Answer 6

they look purple-blue under a light microscope.

E.G. methicillin-resistant Staphylococcus aureus

Question 7

What is Gram -

Answer 7

appear red under microscope.

E.G. the gut bacteria E.coli.

Question 8

What is bacteria’s mode of action

Answer 8

1. most produce and release toxins
2. the toxins poison the host cell to cause disease
3. other bacterial toxins break down the cell membrane or damage host enzymes
4. toxins are a natural by-product of bacteria

Question 9

What are viruses

Answer 9

very successful pathogens which reproduce rapidly so can evolve rapidly

Question 10

What’s the basic structure of a virus

Answer 10

1. protein coat

2. DNA or RNA

Question 11

How do viruses make more viruses

Answer 11

invade host cells and hijack the cell to make more

Question 12

What’s a viruses mode of action

Answer 12

1. the virus attaches to the membrane of a host cell
2. it inserts a viral nucleic acid into the cell
3. the viral nucleic acid replicates quickly in the cell
4. leads to synthesis of the viral protein
5. the proteins and nucleic acids join to form viral particles
6. through lysis, the particles leave the host cell

Question 13

What is fungi

Answer 13

eukaryotes, don’t often affect animals, cannot photosynthesise so digest nutrients extracellularly, some are saprophytes and others are parasites; parasitic fungi cause infectious diseases and can be seen on leaves of plants

Question 14

What’s a fungi’s mode of action

Answer 14

some damage host tissue directly; fungi can digest living cells, destroying them.
Other fungi produce toxins

Question 15

What are protista

Answer 15

Eukaryotes who have single cells and colonies; the ones that cause diseases are parasitic; some may need a vector to enter the body, others can be transmitted through water etc.

Question 16

What’s a protista’s mode of action

Answer 16

it varies; many multiply within infected blood cells causing them to rupture; once released the merozoites can infect other red blood cells.