Exam 42: Water and Electrolyte Balance in Animals

Table 42.1 -The intercellular concentration of three electrolytes is compared with the concentration of these electrolytes in fluid eliminated from the shark rectal gland in Table 42.1.Based on the data,which of the following is a likely function of the rectal gland?

Freshwater fish reside in hypotonic environments.They do not drink water,and they excrete large volumes of hypotonic urine in an effort to osmoregulate.How do they obtain an adequate supply of electrolytes?

How does ion composition of pre-urine differ from hemolymph?

What is the function of the shark rectal gland?

Figure 42.1 -Where does filtration take place in the figure above?

For filtration to take place through the fenestrated capillaries of the renal corpuscle,

Which of the following most accurately describes selective permeability?

Which of the following affects the osmolarity of a solution?

What role does Na⁺/K⁺-ATPase play in salt excretion by the shark rectal gland?

Gas exchange in insects takes place across the epithelium of the tracheae (a system of tubes).The tracheal system connects to the outside air by openings called spiracles.Muscles just inside each spiracle can control the opening to minimize water loss.What would happen if the muscles inside each spiracle were unable to function?

Freshwater fish live in a hypotonic environment.To maintain homeostasis in this environment,they must

Paramecia live in pond water (a hypotonic environment).They have a structural feature,a contractile vacuole,that enables them to osmoregulate.If you observed paramecia in the following solutions,at which sucrose concentration would you expect the contractile vacuole to be most active?

Urine formation is involved in water and electrolyte balance in vertebrates.Which of the following statements is the most correct regarding urine formation?

Through studies on the Malpighian tubules,researchers found that K⁺ accumulated on the inner face of the tubule,against its concentration gradient.What can you infer about the mechanism of transport?

Terrestrial organisms lose water through evaporation.Why are desert locusts and flour beetles good organisms to use in studying mechanisms to regulate water loss?

Different habitats pose certain challenges to animal survival.For instance,terrestrial insects must maintain water balance by minimizing evaporation.How do insects minimize water loss?

On a very hot,dry day,you lose ________ through the skin.

A potassium ion gradient is set up in the Malpighian tubules through an active transport process.As a result,potassium concentration is higher in the lumen of the tubules than in hemolymph.How would the potassium gradient affect water movement?

The products of filtration in the renal corpuscle enter the renal tubule through which of the following structures?

Tissues of sharks are isotonic to seawater,but their concentrations of sodium ions,potassium ions,and chloride ions in cells and extracellular fluids are similar to those of freshwater fishes.What can you infer about the movement of sodium and chloride in these animals?