communicable diseases (chapter 12)

Question 1

types of pathogens

Answer 1

• bacteria : gram positive bacteria appear purple-blue under a microscope, gram negative appear red, Prokaryotic.
• viruses : non-living , reproduce rapidly, parasites.
• protoctista : eukaryotic organisms, parasitic, include single celled organisms.
• fungi : eukaryotic organisms, multicellular, spread rapidly by producing spores.

Question 2

plant diseases

Answer 2

• ring rot : bacterial disease of potatoes and tomatoes. Caused by gram positive bacterium, damages leaves tubers and fruit, no cure.
• tobacco mosaic : a virus that affects tobacco plants and other species like tomatoes, peppers, cucumbers. Damages leaves, flowers, fruit, stunting growth, no cure.

-potato blight : caused by a fungus like protoctist. Destroys leaves, tubers, and fruit. No cure

• black sigatoka : a banana disease caused by a fungus which attacks and destroys the leaves. Turns the leaves black, fungicide can control the disease but no cure.

Question 3

animal diseases

Answer 3

• tuberculosis (TB) : a bacterial disease in humans, cows, pigs, badgers and deer. Damages and destroys lung tissue, suppresses the immune system. Those affected by HIV/AIDS are more likely to get TB. Antibiotics can cure TB.
• bacterial meningitis : a bacterial infection of the meninges of the brain. Can spread to the rest of the body and can cause rapid death. Blotchy red/ purple rash, antibiotics can cure if caught early.
• HIV/AIDS : caused by HIV which targets T helper cells in the immune system. It gradually destroys the immune system leading to more infections. Spread through bodily fluids. No cure.
• Influenza : a viral infection of the ciliated epithelial cells in the gas exchange system. This leaves airways open leading to other infections. No cure.
• Malaria : Caused by protoctista and spread by bites of mosquitos. Invades the red blood cells, liver and the brain. The key is to control the vector.
• ring worm : a fungal disease affecting cattle, dogs, cats and humans. Symptoms are white crusty infections circular areas of the skin. Antifungals creams can cure.
• athletes foot : caused by fungus, grows on warm moist skin between the toes. Itchy and sore, antifungals cure.

Question 4

transmission of pathogens in animals

Answer 4

direct : DIRECT CONTACT, INOCLUATION, INGESTION
indirect : FOMITES, DROPLET, VECTORS

Question 5

producing toxins to damage host cells

Answer 5

most bacteria produce toxins that damage host cells which leads to disease.
- they either damage host cells by breaking down cell membranes, damaging enzymes and interfere with genetic material so that the cells don’t divide.