Transport

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Transport
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Aim How does transport occur in lower organisms?
I. Transport the life function by which
substances are absorbed, circulated, and released
by living things.
A. Absorption the first stage of transport.
1. It is the process by which cells take
dissolved materials and through the plasma
membrane into the cells interior.
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2. The materials that may be absorbed are the end
products of digestion, dissolved gases, salts and
other materials necessary for life.
B. Circulation the second stage of transport.
1. When absorbed materials are moved from one
area to another within an organism.
2. Materials may be moved by diffusion, and in
more complex organisms, a vascular system is
needed.
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II. Transport in the Ameba and the Paramecium
A. Since these organisms are unicellular,
materials just circulate throughout the cell.
1. Cyclosis the fluid of the cell circulates.
Also known as cytoplasmic streaming.
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II. Transport in the Hydra
A. Has two cell layers in which every cell is in
direct contact with its environment.
1. Thus, it does not need a circulatory system.
Materials are absorbed by diffusion from cell to
cell.