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Biology > 6.2 > Flashcards

6.2 Flashcards

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1
Q

what are bacteriophages

A

viruses that attack and destroy bacteria

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2
Q

when do viruses cause symptoms of disease

A

when they lyse
some viral protein coats act as a toxin

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3
Q

how are viruses specific to particular tissues

A

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

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4
Q

what is an epidemic

A

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

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5
Q

what is a pandemic

A

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

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6
Q

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

A

A,B & C
A is the most deadly

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7
Q

what are the subsets of these influenza strains named by

A

specific antigenic markers e.g. H1N1

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8
Q

define mode of transmission

A

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

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9
Q

what are the 3 main ways influenza is spread

A

droplet infection
contaminated surfaces
contact with feces or mucous

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10
Q

what is a zoonotic infection

A

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

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11
Q

define mode of infection

A

the way a pathogen causes infection

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12
Q

what is influenzas mode of infection

A

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

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13
Q

how does influenza kill

A

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

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14
Q

what is the pathogenic effect

A

the symptoms of disease a pathogen causes

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15
Q

what are the symptoms of influenza

A

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

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16
Q

why is influenza so hard to treat

A

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

17
Q

what are fungi cell walls made of

A

chitin & glucans

18
Q

what is a hyphae

A

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

19
Q

which fungus threatens wheat & barley crops

A

stem rust fungus (Puccinia graminis)

20
Q

how is stem rust fungus transmitted

A

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

21
Q

how does the stem rust fungus infect plants

A

-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

22
Q

what is a mycelium

A

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

23
Q

what are the signs of stem rust fungus

A

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

24
Q

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

A

-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

25
Q

state 5 ways of controlling stem rust

A

-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)

26
Q

what are protozoa

A

unicellular
eukaryotic
organisms

27
Q

how is malaria transmitted

A

transmitted to a human host by a female anopheles mosquito vector

28
Q

describe the mode of infection for malaria

A

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

29
Q

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

A

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

30
Q

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

A
  • 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
31
Q

what is an endemic disease

A

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

32
Q

what are the issues with trying to treat endemic diseases

A
  • often widespread so difficult to track down and remove sources of infection
  • requires cooperation of a large population to eradicate
  • expensive
33
Q

what are the treatments of malaria

A

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

34
Q

why is malaria so hard to treat/prevent

A

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

35
Q

what is the most effective way of preventing malaria

A

controlling the vector (mosquitos)

36
Q

how can you reduce contact with mosquitos

A
  • have mosquito screens on doors and windows
  • sleep under mosquito nets
  • use insect repellents and insecticides
  • cover as much skin as possible
37
Q

where does the lifecycle of an anopheles mosquito mainly take place

A

in water

38
Q

how can mosquito breeding be prevented

A
  • 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)
39
Q

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

A

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

Biology (33 decks)

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