"Transport systems play an essential role in the survival of flowering plants and mammals"Large multicellular organisms such as flowering plants and mammals require specialised transport systems to provide sufficient exchange of needed materials and waste products. The movement of substances, in larger organisms, through body fluids between the external surface and internal cells by diffusion alone would be insufficient in meeting cellular requirements. Tiny organisms have a high surface area to volume ratio and can therefore directly exchange materials with the environment to adequately meet requirements of all cells. Larger organisms have a lower surface area to volume ratio and as a result the distances to be covered through the external surface by diffusion would be too far to effectively meet the requirements of all cells. Hence, flowering plants (vascular plants) and mammals have developed specialised transport systems and effective exchange organs (leaves, roots, guts and lungs) to efficiently transport required substances to and from all cells.
Materials that are moved throughout the transport systems of flowering plants include water, carbohydrates (sugars), dissolved mineral ions and organic substances (amino acids) while oxygen, nutrients, hormones, carbon dioxide and waste products are the materials transported in mammals. In flowering plants water and mineral ions (macro and micronutrients) are absorbed by root hairs from the soil and passed into xylem tissue which passively transports the water and dissolved nutrients upwards throughout the plant to the leaves. Sugars created by photosynthesis are actively transported from the leaves of the plant through to the phloem tissue usually in the form of sucrose to other parts of the flowering plant either for storage in developing fruits or to be used for energy. Sucrose is also transported down phloem tissue from sources to sinks which store the sucrose as starch for future use. Oxygen, nutrients (amino acids,