Surface area and Volume Flashcards
Why do single-celled organisms not need exchange and transport systems?
The substances can diffuse directly across the cell membrane. The diffusion rate is quick because of the small distances the substances have to travel.
Why is diffusion across the cell membrane of multicellular organisms too slow?
There is a big distance between the cells and the outside environment as some cells are deep within the body. Larger animals have a low SA: V ratio. This makes it difficult to exchange oxygen to such a large volume of cells through a relatively small surface area.
What is the link between an animal’s size and SA: V ratio?
The larger an animal is the smaller their surface is compared to its volume meaning they have a low SA: V ratio. If an animal is smaller they have a larger surface area compared to their volume meaning they have a high SA; V ratio.
What is the link between an animal’s SA: V ratio and metabolic rate?
The larger an animal is the smaller their surface area meaning they lose heat less easily and they have a lower metabolic rate. The smaller an animal is the larger their surface area meaning they lose heat more easily. Their metabolism is higher because they need to generate more heat to keep them warm.
