Viruses are infectious agents that are not classified as living organisms.
State two life processes that viruses cannot carry out independently (when outside a host cell).
Name one disease in humans that is caused by a virus.
Viroids are plant pathogens discovered in the 20th century. Viroids consist solely of a short, circular strand of RNA and do not possess a protein coat.
Suggest two structural or functional differences between viroids and typical viruses.
7 exam-style questions on Edexcel IGCSE Biology Characteristics of living organisms. Each one has a worked solution and a mark scheme showing where the marks go.