C12

Question 1

What are the 4 Types of pathogen

Answer 1

Bacteria, Viruses, Fungi, Protoctista

Question 2

What are the 2 ways in which we can classify bacteria

Answer 2

By Shape - Rod, Spherical, Comma, Spiralled, Corkscrew
By cell wall - Gram Positive (blue), Gram negative (Red)

Question 3

What’s the base structure of a virus

Answer 3

Non living, Genetic material surrounded by proteins

Question 4

How does a virus infect

Answer 4

Takes over the genetic material of host cell

Question 5

Why are viruses the ultimate parasite?

Answer 5

Reproduce rapidly, Infect bacteria, Take over the whole cell for food

Question 6

Are protoctista single or multicellular?

Answer 6

Both, some single cells and some cells grouped into colonies

Question 7

What is a parasite

Answer 7

Use host as a source for food

Question 8

How do fungi eat food?

Answer 8

Saprophytes - Feed on dead and decaying matter

Question 9

When fungi reproduce, what do they produce?

Answer 9

Millions of tiny spores that can spread long distances, e.g through the wind (A type off vector)

Question 10

What are the 2 ways a pathogen acts on a cell

Answer 10

Damaging cell directly - E.g. viruses take over cell metabolism. Fungi digest living cells and destroy them.
Producing toxins which damage tissues - Bacteria produce toxins, some of these inactivate enzymes, some interfere with genetic material

Question 11

Give an example of a bacterial, fungal and viral disease in PLANTS

Answer 11

Bacterial - Ring rot

Viral - Tobacco mosaic virus

Fungal - Potato Blight, Black Sigatoka

Question 12

Give an example of a Bacterial disease that acts on humans. Explain how it works and how it can be cured.

Answer 12

Bacterial meningitis - Brain, can spread to rest of the body. Blotchy red rash. Antibiotics can be used

Tuberculosis - Damages and destroys lung tissues and suppresses immune system. Makes body less able to fight other diseases. TB is durable through antibiotics

Question 13

How does ring rot operate and what is its cure. (If any)

Answer 13

Damages the leaves, tubers and fruit. No cure

Question 14

How does TMV work

Answer 14

Damages Leaves, flowers, fruit and stunts growth, reducing yield.

Question 15

Name 3 ways in which a pathogen can transfer directly

Answer 15

Contact - Kissing, Skin to skin
Inoculation - Through break in skin
Ingestion - Taking in contaminated food or drink

Question 16

Name three ways in which a pathogen can transfer indirectly

Answer 16

Fomites - Bedding etc
Droplet infection - Saliva and mucus spit out of mouth
Vectors - For example mosquitoes

Question 17

Give an example of how We can minimize the transfer of disease from animals to humans

Answer 17

Minimize in close contact, washing hands after touching the animals

Question 18

Name as many factors as possible affecting the transmission of communicable disease in animals

Answer 18

Overcrowded living and working conditions, poor nutrition, compromised immune system, poor disposal of waste, climate change, culture an infrastructure, lack of trained health workers

Question 19

What are two ways plants can be affected indirectly?

Answer 19

Soil contamination

Vectors

Question 20

Plants can be affected indirectly by vectors explain four types of vecrors they can be affected by

Answer 20

Wind - Can carry bacteria viruses fungus and spores
Water - Spores swim in the surface film of water on leaves. Splashes can cause transmission
Animals - Insects and birds and carry pathogens two plants as they feed
Humans - Pathogens and spores can be transferred By hands


Question 21

Name of many factors affecting the transmission of communicable diseases in plants

Answer 21

Planting varieties of crops that are susceptible to disease, overcrowding, poor mineral nutrition, damp warm conditions, climate change
- All increase the risk of developing a communion disease

Question 22

Explain in as much detail as possible the 3 steps in which a plant recognizes an attack

Answer 22

1. Receptors on cells respond to molecules from pathogens
2. Stimulates the release of signaling molecules that switch on genes in the nucleus
3. Triggers cellular response, such as chemicals being produced

Question 23

How does Callose aid pathogen defense

Answer 23

• When attacked, plants produce high levels of Callose. Callose is synthesized deposited between cell walls and cell membranes of cells around the infected ones. It acts as a barrier, preventing pathogens entering the plant around the site of infection.
• Callose is continuously added, blocks sieve plates in the phloem , Sealing off the infected part
• Callose is deposited in between the infected cells and Neighbor’s, stopping the spread

Question 24

Name four examples of chemical defenses

Answer 24

Insect repellent’s, insecticides, antibacterial compounds, antifungal compounds, Anti Oomycetes, general toxins

Question 25

Name for non-specific defenses keeping pathogens out

Answer 25

Skin, mucous membranes, lysozymes, coughs and sneezes

Question 26

Explain the blood clot cascade

Answer 26

1. Tissue is damaged and platelets are activated which release thromboplastin.
2. Thromboplastin catalyses the formation of thrombin from prothrombin and calcium
3. Thrombin catalyses the formation of fibrin from fibrinogen. Fibrin then forms a clot.

Question 27

Explain the inflammatory response

Answer 27

1. Mast cells are activated by damaged tissues and release cytokines and histamines.
2. Histamines make blood vessels dilate, causing heat and redness. Blood plasma leaks put, becoming tissue fluid
3. Cytokines - attract white blood cells to site, get rid of pathogens via phagocytosis.

Question 28

How does a fever work?

Answer 28

When pathogen invades, cytokines stimulate hypothalamus to reset the thermostat, therefore temp goes up.