Question

Mention any three main differences between circulation in higher plants & higher animals.

Answer 1

Organisms need to move (transport) many different types of substances to wherever they are needed within the organism. This is important in order for cells to breathe and to receive energy, instructions, and materials for maintenance and cell functions. Animals also need to be able to remove from their bodies unwanted substances, such as waste products e.g. carbon dioxide.

Singled-celled (unicellular) organisms can move all the materials they need, which are also referred to as 'particles', by diffusion across their cell membrane and within the cytoplasm of the cell. Other very small organisms (microorganisms) can also move substances via diffusion and other types of movement across biological membranes. *Larger animals need a transport system or transport systems to convey respiratory gases, absorbed food material, waste products of metabolism and other substances around the body

*Their need for transport systems can be explained in terms of the surface area to volume ratio of the organism, e.g. animal.


What are the main types of circulation systems (circulatory systems) in animals?

Not all animals have blood circulation systems e.g. some microorganisms such as unicellular amoeba don't need any circulation system. Many larger animals, even tiny insects, have circulation systems that move fluid around their bodies as a means of transporting supplies and waste products to/from cells (dissolved in the fluid).

There are two types of fluid circulation systems in animals.