Download Transport

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.
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.
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.
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.