The table lists some structures that provide specialized surfaces for the exchange or uptake of substances.
Complete the table by naming the organ in which each structure is found. The first one has been done for you.
| Structure | Organ |
|---|---|
| alveolar sac | lung |
| gill lamellae | |
| microvillus | |
| stomata |
What is meant by the term active transport?
Marine fish must constantly excrete excess sodium ions (Na+)(\text{Na}^+)(Na+) from their blood into the surrounding seawater, which has a much higher concentration of sodium ions.
Describe how sodium ions are transported from the blood of the fish into the seawater.