Viruses (2)

Question 1

Why is a virus not a cell?

Answer 1

It is not a cell as it has no nucleus, cytoplasm or organelles.

Question 2

What is the structure of a virus? (3)

Answer 2

• Envelope
• DNA/RNA
• Protein Coat (Capsid)

Question 3

Do viruses only have RNA?

Answer 3

No, they have a simple structure consisting of a core of DNA or RNA but NOT both.

Question 4

The hereditary material is not enclosed in a ___ membrane.

Answer 4

Nuclear

Question 5

What is the capsid?

Answer 5

The protein coat which surrounds the nucleic acid in a virus.

Question 6

What is the function of the envelope?

Answer 6

The envelope is used to protect the virus from the host’s nuclease enzymes

Question 7

Which effects do viruses have on the body? (4)

Answer 7

• The infected cells can be destroyed. They may swell and burst, e.g. as in nerve cells infected with the rabies virus.
• The host cell’s functioning may be interfered with, e.g. as in ciliated epithelial cells infected with the influenza virus
• The virus can interact with the host cell’s chromosomes causing a mutation, e.g. warts and cancer cells can be formed in this way
• The immune system becomes activated which may lead to fever, tiredness or a disease.