NIST subscription sites provide data under the NIST Standard Reference Data Program, but require an annual fee to access. The purpose of the fee is to recover costs associated with the development of data collections included in such sites.IST subscription sites provide data under the NIST Standard Reference Data Program, but require an annual fee to access. The purpose of the fee is to recover costs associated with the development of data collections included in such sites.
The contractile vacuole allows free-living protists to expel extra water. <b>The contractile vacuole allows free-living protists to expel extra water <br /></b>.
Protists have salt particles inside their cytoplasm. When they are in freshwater the concentration of salt particles inside is higher than outside... however when they are in â¦salt water the concentration is equally spread... (diffusion) the contractile vacuole job is to remove excess water... but if its in saltwater.. there isn't a need because. Of the diffusion that takes place.