In salt water fish, chloride cells in the gills: a. actively transport Cl- from the plasma to the ECF. b. actively transport Cl- from the ECF to the external environment. c. passively transport Cl- from the ECF to the external environment. d. actively transport Cl- from the external environment to the ECF.

b. actively transport Cl- from the ECF to the external environment.

Explanation:

Chloride cells are cells that are found in the gills of teleost fishes which pump large amount of sodium and chloride ions out from the extracellular fluid (ECF) into the sea or environment against a concentration gradient in marine fish.

The opposite of this process occurs in freshwater fishes where the gills of freshwater teleost fish, cause an influx of sodium and chloride ions into the fish from the environment, also against a concentration gradient.

Mechanism of action

Salt water teleost fishes take in large amounts of seawater to decrease osmotic dehydration. The excess of ions derived from seawater is thrown out of the teleost fishes through the chloride cells. These cells employs active transport on the basolateral (internal) surface to diffuse in chloride, which then is pumped out of the apical (external) surface, straight into the surrounding environment. Such mitochondria-rich cells are located in the region of the gill lamellae and filaments of teleost fish.

what's the

a tetrad is the foursome during meiosis made by two homologous chromosomes that have each already replicated into a pair of sister chromatids.