Viruses

Question 1

structure

Answer 1

either DNA or RNA present
protein based coat called a capsid
differ in shape depending on these factors

Question 2

retrovirus

Answer 2

virus that contains RNA

eg coronavirus

Question 3

viruses that affect certain organisms

Answer 3

animals - foot and mouth
plants - tobacco mosaic virus
humans - common cold

Question 4

bacteriophage

Answer 4

virus that uses a bacterial cell as a host

Question 5

beneficial medical effects

Answer 5

viruses used to make vaccines eg MMR vaccine

bacteriophages are used to kill certain eg lambda attack E.coli

Question 6

harmful medical effects

Answer 6

cause diseases that cant be cured by antibiotics

some diseases cant be protected against with a vaccination eg HIV, but some can be protected by vaccination eg measles

Question 7

harmful economic effects

Answer 7

cause crop damage, significant loss to farmers income

viral diseases can lead to death, which leave children orphaned who need to be cared for

Question 8

non living features

Answer 8

no cell organelles
cant reproduce independently
have either DNA or RNA not both

Question 9

living features

Answer 9

contain genetic material (DNA or RNA)
contain a protein coat
can replicate

Question 10

why don’t they belong to a kingdom

Answer 10

no cell organelles or metabolism outside their host

Question 11

replication

Answer 11

obligate parasites as can only replicate in host cell

Question 12

outline replication

Answer 12

surface proteins on the virus must be able to bind with the proteins on the surface of the host cell to replicate

1. virus attaches to target proteins specific host cell
2. virus inserts its nucleic acid into the cell and gains entry
3. it inactivates the host DNA and replicates
4. more viruses are produced and assemble together
5. host cell bursts and new virus released

Question 13

lysogenic cells

Answer 13

cells which contain viral DNA but remain dormant
this may have no apparent effect but environmental factors in later generations may cause the virus to become active again

Question 14

why are antibiotics prescribed for the flu

Answer 14

antibiotics are not effective against viruses as they are only toxic to bacteria
if antibiotics are taken for a viral infection, it may promote the development of resistant bacteria

Question 15

control of viruses

Answer 15

general defence and specific defence system control viruses

immunity to many viruses can be produced artificially by vaccination or injecting antibodies directly into the blood