34. Viruses

Question 1

Virus shapes

Answer 1

Rod
Round
Complex

Question 2

Virus structure

Answer 2

1. Surrounded by a protein coat (chemical component)
2. Inside is nucleic acid, either DNA or RNA
3. No organelles-so no metabolic reactions, so require host cells to carry out these reactions

Question 3

Why are viruses not seen as living or non living

Answer 3

1. Have either DNA or RNA-living have both, non living have neither
2. Have no organelles- living things have organelles
3. Cant reproduce by themselves-need a host-obligate parasite

Question 4

Disadvantages of viruses

Economic importance

Answer 4

1. Causes contagious human diseases: Measles, mumps, rubella, colds
2. Causes plant diseases, causes spots on plants- potato and tomato mosaic diseases
3. Causes animal diseases-foot and mouth, rabies

Question 5

Advantages of viruses

Economic importance

Answer 5

1. Control bacterial infections

2. Mosaic patterns give new variety to garden plants

Question 6

How to control viral infections

Answer 6

1. Antibiotics have no effect on them.
2. Controlled by body’s own defence system-production of antibodies
3. Vaccine

Question 7

How do viruses reproduce

Answer 7

They can only reproduce using a host cell-obligate parasites

Question 8

Obligate parasite def.

Answer 8

An organism which can only reproduce using a host cell

Question 9

Process of viral reproduction

step 1

Answer 9

1. Attachment and entry:

virus attaches to host cell and inserts its nucleic acid into the hosts cytoplasm

Question 10

Process of viral reproduction

Step 2

Answer 10

Synthesis and Assembly:
Viral nucleic acid breaks down the hosts DNA and forces the host to make viral DNA (Synthesis) and new copies of the virus (Assembly)

Question 11

Process of viral reproduction

Step 3

Answer 11

Release:

The new virus bursts out of the host cell to infect further cells

Question 12

What is a bacteriophage

Answer 12

Virus that infects a bacteria

Question 13

What is a bacterium

Answer 13

Bacteria that is infected

Question 14

What is the biochemical component of the Virus

Answer 14

DNA or RNA

Question 15

What is the chemical component of the virus

Answer 15

Protein coat