Disease

Question 1

what is a pathogen?

Answer 1

an organism that causes disease

e. g.
- bacteria
- viruses
- fungi
- protoctists

Question 2

describe bacteria

Answer 2

• prokaryotic organisms
• no nucleus
• microscopic and unicellular

Question 3

name a useful bacteria

Answer 3

Lactobacillus bulgaricus

Question 4

what shape is lactobacillus bulgarius?

Answer 4

rod shaped

Question 5

what does lactobacillus do?

Answer 5

feed on lactose sugar in milk and produce lactic acid

Question 6

what does harmful bacteria do?

Answer 6

cause infections

Question 7

name a harmful bacteria and what it causes.

Answer 7

pneumococcus - causes pneumonia - spherical

Question 8

describe viruses

Answer 8

• non living
• parasitic - they can only reproduce by invading living cells
• they infect all living organisms

Question 9

how do viruses reproduce?

Answer 9

1. the virus sticks to a cell membrane
2. the virus enters the cell, the protein coat breaks down and releases DNA
3. the viral DNA directs the cell to make new protein coats
4. the cell membrane breaks down to release the new viruses

Question 10

what is the influenza virus?

Answer 10

• infects animal cells
• in humans it infects cells in the nose and throat
• causes flu

Question 11

what is the HIV virus?

Answer 11

• infects white blood cells in humans
• as a result the white blood cells can’t fight other diseases
• HIV can cause AIDs

Question 12

what is the tobacco mosaic virus?

Answer 12

• infects leaf cells of tobacco plants
• infected cells can’t make chloroplasts
• causes discoloured leaves
• can kill the plants

Question 13

what is an antigen?

Answer 13

• microbes have chemicals on their surfaces called antigens
• each type of microbe has a different antigen
• lymphocytes make antibodies specific to the antigen on the invading microbe

Question 14

do white blood cells have haemoglobin?

Answer 14

no