Biology » Introduction to Biology » The Scientific Method

Some Important Principles in Biology

Important Principles and Relationships in Biology

Surface area and volume

Depending on the system it is advantageous to either have a large surface to volume ratio or a small surface to volume ratio.

This is highlighted in the following examples:

  • Flatworms and leeches have more surface area to volume to increase the area for diffusion for nutrients and respiratory gases across their whole bodies.
  • In animals the shapes of organs are defined by surface area to volume requirements. For example, in the lungs there are many branches to increase the surface area through which gases can be exchanged.
  • Cells with a greater volume compared to surface area are able to metabolise more and ingest and excrete more through the membrane.

Structure and function

In living organisms, the structure of a particular biological feature is related to what function it performs. Thus for all the structures you will study in biology, the important questions to ask are the following:

  1. What makes this structure suited to its function?
  2. How has the structure adapted to its function?
  3. Why is this structure so efficient for its function?

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