6.2

Question 1

what are bacteriophages

Answer 1

viruses that attack and destroy bacteria

Question 2

when do viruses cause symptoms of disease

Answer 2

when they lyse
some viral protein coats act as a toxin

Question 3

how are viruses specific to particular tissues

Answer 3

due to the presence of antigenic markers on the surface of host cells, each type of virus can only bind to particular antigens

Question 4

what is an epidemic

Answer 4

a higher than average number of people are infected with a disease in a particular area or country

Question 5

what is a pandemic

Answer 5

a higher than average number of people are infected with a disease across a number of countries

Question 6

what are the 3 main strains of influenza and which is most deadly

Answer 6

A,B & C
A is the most deadly

Question 7

what are the subsets of these influenza strains named by

Answer 7

specific antigenic markers e.g. H1N1

Question 8

define mode of transmission

Answer 8

the different ways a pathogen is spread from one host to another

Question 9

what are the 3 main ways influenza is spread

Answer 9

droplet infection
contaminated surfaces
contact with feces or mucous

Question 10

what is a zoonotic infection

Answer 10

an infection in a person caused by a pathogen that can cross the species barrier from other animals

Question 11

define mode of infection

Answer 11

the way a pathogen causes infection

Question 12

what is influenzas mode of infection

Answer 12

infects ciliated epithelial cells of respiratory system, viral RNA reaches nucleus, new viral particles made, cell lyses

Question 13

how does influenza kill

Answer 13

death of ciliated epithelial cells of trachea and bronchi when cell lyses leaves airway open to severe secondary bacterial infections

Question 14

what is the pathogenic effect

Answer 14

the symptoms of disease a pathogen causes

Question 15

what are the symptoms of influenza

Answer 15

fever, shivering & sweating, loss of appetite. aching muscles, painful joints

Question 16

why is influenza so hard to treat

Answer 16

it is an RNA virus therefor it is more prone to mutation so it is constantly monitored for emergence of new flu strains

Question 17

what are fungi cell walls made of

Answer 17

chitin & glucans

Question 18

what is a hyphae

Answer 18

a thread-like fungal structure that is a single unit of mycelium

Question 19

which fungus threatens wheat & barley crops

Answer 19

stem rust fungus (Puccinia graminis)

Question 20

how is stem rust fungus transmitted

Answer 20

spores from infected wheat plants/berberis are carried to young crops by the wind infected plants left in the soil

Question 21

how does the stem rust fungus infect plants

Answer 21

-spores land on host & need water to germinate
-hypha emerges from spores & penetrated the stomata
-the hypha secretes enzymes which digest cells & nutrients
-hyphae branches to form mycelium that feeds & grows

Question 22

what is a mycelium

Answer 22

a fungal body made up of a mass of thread-like hyphae

Question 23

what are the signs of stem rust fungus

Answer 23

rusty red pustules break through epidermis of the stem which eventually goes black and the crop becomes blackened

Question 24

how does the stem rust fungus effect the crop and their impacts

Answer 24

-absorbs nutrients from plant reducing yield
-breaks epidermis, harder to control transpiration, less efficient metabolism, drys out plant
-mycelium grows in vascular tissue, absorbing water & nutrients
-weakens stem, more likely to fall over, less effective harvesting

Question 25

state 5 ways of controlling stem rust

Answer 25

-bigger spaces between plants reduces moisture, increases distance to travel -reduce use of fertilizers -early maturing crops (avoid time of max spread) -remove wild berberis (interrupt life cycle) -use fungicides (expensive)

Question 26

what are protozoa

Answer 26

unicellular eukaryotic organisms

Question 27

how is malaria transmitted

Answer 27

transmitted to a human host by a female anopheles mosquito vector

Question 28

describe the mode of infection for malaria

Answer 28

the malaria parasite enters the blood by a female anopheles mosquitos it then travels to the liver until the next stage it will then re-enter the blood and invade red blood cells and begin to reproduce asexually at regular intervals (48-72 hours) the parasite bursts out of the red blood cells destroying them it then goes on to infect more red blood cells this continues in cycles some of the parasites become gametocytes and are taken into a female anopheles mosquito during a blood meal

Question 29

describe the symptoms of malaria (long term & short term)

Answer 29

fever, sweating, shaking, muscle pains and headaches long term liver damage and a reduction in the number of red blood cells which leads to weakness, anemia and eventually death

Question 30

how is the plasmodium parasite (malaria) well adapted for survival

Answer 30

- it can take advantage of more than one host - it can survive dormant for a long time without moving to a new host - spends most of its time inside the liver or red blood cells therefor it is hidden from the immune system so it cannot be destroyed - it takes a long time to kill the host therefor there are many opportunities for it to be passed on

Question 31

what is an endemic disease

Answer 31

one in which the active disease or pathogen that causes the disease is constantly present in a particular country or area

Question 32

what are the issues with trying to treat endemic diseases

Answer 32

- often widespread so difficult to track down and remove sources of infection - requires cooperation of a large population to eradicate - expensive

Question 33

what are the treatments of malaria

Answer 33

there are drugs (quinine, chloroquinine, artemisinin) that kill the parasite and prevent it returning but they are only effective of they are taken soon after infection it is advised to take anti-malarial medicines in advance so that the pathogen is destroyed before it can infect the host often a combination of drugs are used as the parasite develops resistance

Question 34

why is malaria so hard to treat/prevent

Answer 34

it hides from the immune system and antigens on its surface are constantly changing

Question 35

what is the most effective way of preventing malaria

Answer 35

controlling the vector (mosquitos)

Question 36

how can you reduce contact with mosquitos

Answer 36

- have mosquito screens on doors and windows - sleep under mosquito nets - use insect repellents and insecticides - cover as much skin as possible

Question 37

where does the lifecycle of an anopheles mosquito mainly take place

Answer 37

in water

Question 38

how can mosquito breeding be prevented

Answer 38

- remove possible breeding sites (ponds, old drink cans etc) - proper disposal of sewage - biological control (seeding local water sources with organisms that feed on mosquito larvae) - chemical control (spraying local water sources with pesticides)

Question 39

what are the issues with the methods of preventing the spread of malaria

Answer 39

social implications - people must be persuaded to change their behavior economic implications - requires substantial economic investment ethical implications - reservations about vaccines, consent in medical trials, spraying insecticides will affect other insects