Characteristics of a Living Organism

Question 1

Why are viruses considered non-living?

Answer 1

• Do not meet all requirements to be an organism

- Unable to reproduce by themselves; force infected cells to synthesise virus DNA/RNA

Question 2

What are some characteristics of viruses?

Answer 2

• Subcellular genetic parasites
• Survive in two stages (virion & parasitic form)
• Forces host cell to reproduce viruses
• Made of proteins and glycoproteins AND contain genes

Question 3

What are three examples of non-living things that have some of these characteristics?

Answer 3

Computer, phone, fire, viruses, ice, clock, etc

Question 4

It was not until 1931 that virus particles were shown to have complex structures. Why was this?

Answer 4

Viruses are sub-cellular, which means that they are too small to be seen with a light microscope, let alone the naked eye. Visual proof of viruses was available only after the invention of electron microscopes.

Question 5

Name the characteristics of a living organism.

Answer 5

Single/Multicellular structure
Ability to reproduce
Ability to grow and develop (number of body cells increases)
Consumes nutrients to produce energy (respiration & metabolism) - and consequently eliminates waste (excretion)
Responds to the environment (responds to any internal/external stimulus)
Homeostasis- maintains an internal environment within tolerable limits
Evolutionary adaption-changes over time