1. Sodium diffuses freely through the cell membrane.
2. The sodium/potassium pump removes sodium ions from the cell.
3. The blood contains a high concentration of sodium.
4. Sodium is actively taken up by the cells for use in the cytoplasm.

1. Water, which is hypotonic with respect to body fluids.
2. Saline at a concentration that is isotonic with respect to body fluids.
3. Glucose because it is a non-electrolyte.
4. blood

1. 100 mOsm
2. 300 mOsm
3. 1000 mOsm
4. It is not constantly maintained.

1. 0.13
2. 0.75
3. 0.5
4. 0.25

1. Osmoregulators can change the osmotic pressure of their body fluids, while osmoconformers cannot.
2. Osmoconformers can change the osmotic pressure of their body fluids, while osmoregulators cannot.
3. Osmoregulators match the osmotic pressure of their cells with that of the environment, while osmoconformers do not.
4. Osmoconformers match the osmotic pressure of their cells with that of the environment, while osmoregulators do not.

1. They need to remove excess salt from ocean water.
2. They move between areas of fresh and salt water.
3. They travel for short stretches across the land between streams.
4. Freshwater is osmotically neutral compared with their body fluids.

1. They exclusively perform an excretory function.
2. They contain digestive enzymes.
3. They originate from the cell membrane.
4. They are only used for fluid storage.

1. exocytosis
2. filtration
3. osmoregulation
4. dilatation

1. Water leaves the Malpighian tubules.
2. Water moves into the Malpighian tubules.
3. K⁺ moves into the Malpighian tubules.
4. K⁺ leaves the Malpighian tubules.

1. arthropods
2. annelids
3. mammals
4. flatworms

1. The cell’s nephrons would no longer be able to reabsorb water.
2. The cell’s cytoplasm would become very concentrated.
3. The cell could no longer excrete waste products.
4. The cell would uncontrollably take on water until it burst.

1. They remain the same size.
2. They shrink due to water loss.
3. They allow water to flow in and out at the same rate.
4. They swell due to water gain.

1. osmoregulation
2. excretion of solid waste
3. production of oxygen
4. reabsorption of all nutrients

1. a network of capillaries
2. the cup-shaped chamber surrounding the glomerulus
3. the functional unit of the kidney
4. the bow-shaped artery at the base of medullary pyramids

1. Juxtamedullary nephrons have a longer loop of Henle, allowing them to regulate urine concentration better than cortical nephrons.
2. Juxtamedullary nephrons have a shorter loop of Henle, allowing them to regulate urine concentration better than cortical nephrons.
3. Juxtamedullary nephrons have a larger glomerulus, allowing them to filter blood at a greater rate than cortical nephrons.
4. Juxtamedullary nephrons have a smaller glomerulus, allowing them to filter blood at a greater rate than cortical nephrons.

1. distal tubule
2. loop of Henle
3. Bowman’s capsule
4. renal pyramid

1. solutes and water
2. proteins and solutes
3. water and proteins
4. water and solutes

1. urea, which is less soluble than uric acid
2. urea, which is more soluble than uric acid
3. ammonia, which is more soluble than uric acid
4. ammonia, which is less soluble than uric acid

1. Blood enters and exits the kidney at the renal hilum, and the renal blood supply starts with the branching of the aorta into the renal arteries. They end with the exiting of the renal veins to join the superior vena cava. Each segmental renal artery formed by the splitting of the renal arteries splits again into interlobar arteries and enters the renal columns. These again split to form arcuate arteries, from which cortical radiate arteries radiate out and branch into many afferent arterioles that enter the capillaries supplying the nephrons. Veins trace the path of arteries and have similar names, except there are no segmental veins.
2. Blood enters and exits the kidney at the renal hilum, and the renal blood supply starts with the branching of the aorta into the renal arteries. They end with the exiting of the renal veins to join the inferior vena cava. Each segmental renal artery formed by the splitting of the renal arteries splits again into interlobar arteries and enters the renal columns. These again split to form arcuate arteries, from which cortical radiate arteries radiate out and branch into many afferent arterioles that enter the capillaries supplying the nephrons. Veins trace the path of arteries and have similar names, except there are no segmental veins.
3. Blood enters and exits the kidney at the renal hilum, and the renal blood supply starts with the branching of the aorta into the renal arteries. They end with the exiting of the renal veins to join the inferior vena cava. Each segmental renal artery formed by the splitting of the renal arteries splits again into interlobar arteries and enters the renal columns. These again split to form cortical radiate arteries that radiate out and branch into many afferent arterioles that enter the capillaries supplying the nephrons. Veins trace the path of arteries and have similar names, except there are no segmental veins.
4. Blood enters and exits the kidney at the renal hilum, and the renal blood supply starts with the branching of the aorta into the renal arteries. They end with the exiting of the renal veins to join the inferior vena cava. Each segmental renal artery formed by the splitting of the renal arteries splits again into interlobar arteries and enters the renal columns. These again split to form arcuate arteries, from which cortical radiate arteries radiate out and branch into many afferent arterioles that enter the capillaries supplying the nephrons. Veins trace the path of arteries and have all the same names as the arteries following the same path.

1. chlorine
2. potassium
3. ammonia
4. sodium

1. ammonia, because it can be easily diluted in an aquatic environment
2. uric acid, because aquatic animals must preserve water
3. urea, because ammonia needs to be converted before it can safely be stored in the body.
4. chlorine, because it can easily be converted to a gas

1. urea
2. guanine
3. ammonia
4. uric acid

1. krebs
2. ornithine
3. citric acid
4. uric acid

1. increases vasoconstriction
2. prevents loss of sodium
3. increases blood pressure
4. prevents water loss

Which hormone elicits the fight or flight response, and under which circumstance is it released?

1. anti-diuretic hormone, presence of alcohol in the blood
2. atrial natriuretic peptide, high blood pressure
3. aldosterone, low water content in the blood
4. epinephrine, extreme stress

1. an excess of uric acid in the blood, uric acid-dissolving drugs
2. an inability to produce adh, drink excess water
3. an excess of K⁺ secretion into the urine, take in excess potassium
4. an inability to produce aldosterone, take in excess sodium

1. vasoconstrictor
2. vasodilator
3. inhibitor
4. vasopressin

1. granular cells of the juxtaglomerular apparatus
2. the liver
3. the nephrons
4. water-reabsorbing cells of the collecting duct