1. Excretion is the process of (1 point)
exchanging carbon dioxide for oxygen.
removing metabolic wastes from the body.***
pumping blood throughout the body to supply nutrients and oxygen to cells.
breaking food down into nutrients that can be absorbed.



2. Kidneys that can conserve water are essential to homeostasis because (1 point)
some animals live in dry or salty environments.
some animals drink water.
urea is not soluble in water.***
their cells will be unable to convert ammonia into urea if excess water is excreted.


3. Many freshwater invertebrates eliminate ammonia by (1 point)
converting it to uric acid and eliminating it with solid wastes.
simple diffusion across the gill membranes.
converting it to urea and eliminating it in their urine.
simple diffusion across the skin.***


4. Which of the following excretory processes do saltwater and freshwater fishes share? (1 point)
They both conserve water by producing small amounts of concentrated urine.
They both actively pump salt across their gills.***
They both avoid drinking water.
They both produce lots of watery urine.


5. What excretory characteristic does a garden spider share with a sparrow? (1 point)
They both convert nitrogenous wastes to uric acid.
They both produce lots of diluted urine.***
They both excrete very concentrated salt solutions.
They both produce very dry feces.