Deck 22: Homeostasis: Water, Solutes and Excretion

Question 1

In animals, which of the following situations indicates that osmoregulation is occurring?

A) The intracellular fluid has the same osmotic concentration as the extracellular fluid.
B) The extracellular fluid has the same osmotic concentration as the environment.
C) The osmotic concentration of the extracellular fluid is greater than that of the environment.
D) The osmotic concentration of the concentration of intracellular fluid is less than that of the extracellular fluid.
E) The osmotic concentration of the intracellular fluid is greater than that of the extracellular fluid.

Answer 1

The osmotic concentration of the extracellular fluid is greater than that of the environment.

Question 2

The removal of water and solutes from the body fluids of animals is referred to as

A) excretion.
B) elimination.
C) osmoregulation.
D) elimination
E) filtration.

Answer 2

excretion.

Question 3

Which of the following is NOT a source of water for terrestrial animals?

A) Drinking.
B) Eating.
C) Evaporation.
D) Metabolism.
E) All the answers are water for terrestrial animals.

Answer 3

Evaporation.

Question 4

Which of the following statements regarding osmosis is INCORRECT?

A) Osmosis is the passive diffusion of water from low to high osmotic concentrations.
B) The osmotic concentration difference between intra and extracellular fluid of cells is kept constant.
C) Fluids with the same osmotic concentrations have the same concentrations of Na⁺ and Cl^-ions.
D) Hydrostatic pressure on plant cell membranes is greater than for animal cell membranes.
E) If the concentration of all ions in two fluids are equal, then they have the same osmotic concentration.

Question 5

A student carried out an experiment in which he measured the drinking rate of hopping mice. The experimental animals were of similar size and weight, and housed in individual enclosures provided with the same amounts of food and water. At the end of the experiment, the student found that the hopping mice could be divided into two groups according to whether they had high or low drinking rates. It would be reasonable to predict that, during this experiment, hopping mice with higher drinking rates also

A) produced drier faeces.
B) had experienced more humid conditions.
C) were less active.
D) were provided with a drier food source.
E) were more active.

Question 6

In aquatic animals

A) water is gained through drinking and solutes are lost by active transport across the body surface.
B) water is gained or lost by osmosis and solutes gained or lost by passive diffusion across the body surface.
C) water is gained only by osmosis and lost via gills.
D) solutes are gained or lost the same way as terrestrial animals.
E) water is gained through drinking and lost by osmosis through the stomach.

Question 7

The osmotic concentration in the body fluids of an osmoconformer is

A) similar to the concentration in the external environment.
B) higher than the concentration in the external environment.
C) lower than the concentration in the external environment.
D) variable and dependent on the external environment.
E) constant.

Question 8

Animals that move between salt and fresh water are able to survive large fluctuations of external osmolarity because they are

A) able to alter the water permeability of their skin, gills and guts.
B) able to tolerate large fluctuations in cell volume.
C) able to change from being osmoconformers in salt water to being osmoregulators in fresh water.
D) able to regulate their extracellular fluid by retaining higher concentrations of urea.
E) osmoregulators that are able to switch from a strategy that conserves water in the marine environment to one that sheds excess water in the freshwater environment.

Question 9

To maintain constant body conditions in fresh water, a fish must

A) actively uptake ions and excrete large volumes of dilute urine.
B) get rid of excess water by osmosis.
C) osmoconform to its environment.
D) activate gill pumps to get rid of excess ions.
E) lose ions by diffusion from their surface.

Question 10

Terrestrial animals

A) allow their ionic composition to fluctuate.
B) get rid of excess water by osmosis.
C) are all osmoconformers.
D) are all ionoregulators.
E) do not secrete ions.

Question 11

Examine the data in the following table.
Animal Environment
[Total solutes] mOsm 1075 1000
[Na⁺] mM 269 460
[Cl^-] mM 258 540
This data suggests that this animal is

A) an osmoconformer and an ionoregulator.
B) an osmoconformer and an ionoconformer.
C) an osmoregulator and an ionoconformer.
D) an osmoregulator and an ionoregulator.
E) The type of osmotic regulation cannot be determined from the information.

Question 12

Most aquatic animals eliminate nitrogenous waste by producing

A) ammonia.
B) urea.
C) uric acid.
D) nitric oxide.
E) All of the answers are correct.

Question 13

Which of the following statements is true?

A) Ammonia is energetically more expensive to produce than urea.
B) Excreting urea requires more water than excreting ammonia.
C) Urea is more toxic than ammonia.
D) Ammonia is more soluble in water than urea.
E) In humans, ammonia is the predominant nitrogenous waste from protein metabolism.

Question 14

The advantage of excreting guanine is that it

A) is relatively soluble.
B) is energetically cheap to produce.
C) can be excreted as a semisolid paste.
D) is non-toxic in solution.
E) may be co-transported with hydrogen ions.

Question 15

The eggs of birds have shells that allow gas exchange but restrict the passage of water. Nitrogenous waste produced by the embryo must be contained within the egg until hatching. This waste is stored in a sac, called the allantois, in the form of

A) ammonia.
B) urea.
C) uric acid.
D) allantoic acid.
E) nitric oxide.

Question 16

The two main types of excretory organs in animals are

A) gill pumps and surface filtration pumps.
B) surface solute pumps and internal tubular organs.
C) surface solute pumps and contractile vacuoles.
D) gill pumps and contractile vacuoles.
E) epithelial salt-secreting glands and gill pumps.

Question 17

The action of epithelial excretory pumps causes

A) osmoconcentration of urine in the kidneys.
B) active transport of water across the body surface.
C) active transport of ions across the gills.
D) reabsorption of ions in Malpighian tubules.
E) active transport of water across the gills.

Question 18

The epithelial excretory pumps of freshwater fishes actively

A) absorb water.
B) excrete water.
C) export Cl^- ions.
D) absorb Cl^- ions.
E) absorb Na⁺ ions.

Question 19

Which of the following processes occurs in tubular excretory organs?

A) Osmosis
B) Filtration
C) Reabsorption
D) Urine formation
E) All of the answers are correct

Question 20

In both protonephridia and Malpighian tubules

A) urine is expelled directly from excretory tubules to the exterior of the body.
B) urine is modified by tubular reabsorption.
C) fluid is transported into excretory tubules by the action of cilia.
D) K⁺ is pumped into the lumen.
E) the primary urine is formed by filtration of coelomic fluid.

Question 21

In the excretory system of the earthworm

A) flame cells collect and concentrate urine.
B) ciliated funnels transport coelomic fluid into excretory tubules.
C) urine is modified by reabsorption and then emptied into the hindgut.
D) urine is formed by filtration of fluid from blood vessels.
E) All of the answers are correct.

Question 22

Which invertebrate excretory system contains branching excretory tubules with blind-ended inner ends, and ciliated cells called 'flame cells'?

A) The protonephridia of flatworms
B) The coelomoducts of hagfish
C) The metanephridia of earthworms.
D) The Malpighian tubules of spiders.
E) The metanephridial tubules of crustaceans.

Question 23

Insects adapted for dry environments may

A) absorb water vapour in the rectum.
B) excrete ammonia.
C) actively transport water into excretory tubules.
D) produce urine that is more dilute than their body fluids.
E) form urine at the blind end of the Malpighian tubules.

Question 24

In the green glands of freshwater crustaceans, a coelomic end sac forms urine by filtration of fluid (haemolymph) from the circulatory system. The filtrate passes through a ciliated funnel and down a coiled tubule, the nephridial canal, where solutes are reabsorbed so that the urine voided to the exterior is more dilute than the body fluids. In structure and function, the green glands of freshwater crustaceans are most like the

A) protonephridia of rotifers.
B) coxal glands of spiders.
C) metanephridia of earthworms.
D) nephrons of freshwater fishes.
E) the rectal pads of blow flies.

Question 25

In vertebrates, which of the following organs is involved in osmoregulation and excretion?

A) Salt-secreting gland
B) Kidney
C) Gills
D) Malpighian tubules
E) All of the answers are correct

Question 26

Glomerular filtration rate

A) is mainly influenced by an animal's need to conserve water.
B) is mainly influenced by the hydrostatic pressure of blood in the glomerulus.
C) depends largely on the colloid osmotic pressure of the fluid in Bowman's capsule.
D) is determined by the total area of the filtration slits in the wall of Bowman's capsule.
E) is dependent on the ion concentration in the collecting duct.

Question 27

In the mammalian kidney, urine in the distal convoluted tubule

A) has already passed through the proximal convoluted tubule but not the loop of Henle.
B) is more concentrated than urine in the proximal convoluted tubule.
C) gains K⁺ by secretion.
D) gains water by osmosis.
E) actively reabsorbs water to concentrate urine.

Question 28

In vertebrate kidneys, which are modified to minimise urine flow and conserve water, which of the following structures would be reduced or absent?

A) Proximal convoluted tubule
B) Distal convoluted tubule.
C) Loop of Henle
D) Glomerulus
E) Malpighian tubules

Question 29

In the nephrons of mammals, which of the following regions contains the most dilute urine?

A) Proximal convoluted tubule
B) Distal convoluted tubule
C) Collecting duct
D) Bowman's capsule
E) Glomerulus

Question 30

Unlike humans, sea birds, such as herring gulls, can drink seawater because their

A) salt gland secretions are hyperosmotic to seawater.
B) urine is hyperosmotic to seawater.
C) urine and salt gland secretions are hyperosmotic to seawater.
D) body fluids are hyperosmotic to seawater.
E) urine as excreted is a concentrated NaCl solution.

Question 31

The release of ADH

A) increases urine volume.
B) is stimulated by high blood osmotic concentration.
C) is stimulated by high blood pressure.
D) is the only control of kidney function.
E) decreases the permeability of the collecting duct wall to water.

Question 32

The nephrons of vertebrates have many functions. These function include all of the following EXCEPT

A) formation of urine.
B) solute reabsorption.
C) solute secretion.
D) H⁺ ion uptake.
E) water reabsorption.

Question 33

The loops of Henle

A) osmoconcentrate urine.
B) pass fluid that is more concentrated than body fluids.
C) actively transport Cl^- into the tubule.
D) establish an osmotic concentration gradient in the renal medulla.
E) are impermeable to water and solutes.

Question 34

Which of the following statements is CORRECT?

A) Urea accumulation does not contribute to the medullary osmotic gradient.
B) All vertebrates can produce dilute urine but only mammals and birds produce urine more concentrated than blood.
C) The kidneys of desert mammals have a low medullary area and so produce highly concentrated urine.
D) Urine is concentrated by active removal of solutes as it passes along the collecting duct.
E) The kidneys of birds do not have loops of Henle to establish as osmotic concentration gradient in the medulla.

Question 35

Reabsorption

A) allows the recovery of Na⁺ and Cl⁺ ions.
B) controls the solute composition of body fluids.
C) occurs mainly in the proximal convoluted tubule.
D) allows the recovery of Na⁺ and Cl⁺ ions and controls the solute composition of body fluids.
E) allows the recovery of Na⁺ and Cl⁺ ions, controls the solute composition of body fluids and occurs mainly in the proximal convoluted tubule.

Question 36

Antidiueretic hormone

A) is inversely proportional to the extent of dehydration.
B) increase in the circulation causes the kidney to lose water.
C) is synthesised in the posterior pituitary.
D) production is stimulated by decreased blood osmotic concentration.
E) All of the answers are correct.

Question 37

Which of the following is NOT essential for biological processes in the intracellular environment?

A) PO₄^3-
B) CN^-
C) SO₄^2-
D) Cl^-, Mg²⁺
E) Na⁺, K⁺

Question 38

A 500mM MgCl²⁺ has an osmotic concentration of

A) 1.5 Osm.
B) 500 Osm.
C) 1 Osm.
D) 15000 µOsm.
E) 5000 mOsm.

Question 39

If an animal passively conforms to its external environment and encounters an area with an unusually high solute concentration, it must be able to

A) move away from the high solute concentration.
B) alter the composition of its external environment.
C) tolerate a similarly high solute concentration to its internal environment.
D) actively regulate its internal environment.
E) prevent the high solute levels from crossing its cellular membrane.

Question 40

Which of the following is NOT an example of a short-term positive feedback mechanism?

A) Shivering
B) Blood clotting
C) Child Birth
D) Urination
E) Defaecation

Question 41

What is a method used by animals to control the movement of water into and out of their cells?

A) All the options listed here are correct
B) Diffusion
C) Epithelia
D) Aquaporins
E) Water channels

Question 42

When environmental sources of water are seriously lacking in volume and/or availability, what can be an alternative source of water gain, particularly in arid-adapted animals?

A) Urine
B) Metabolic water
C) Uric acid
D) Blood
E) Dew

Question 43

Marine cartilaginous fishes ionoregulate their internal environment, with extracellular Na⁺ and Cl^- concentrations (total concentration about 600 mOsm) lower than sea water. Given that these two ions predominatly occur as NaCl, what would be the molar concentration of NaCl in the cartilaginous fishes?

A) 600mM
B) 300M
C) 600µM
D) 300mM
E) 1.2M

Question 44

A marine organism is found to have very high levels of urea that would normally cause deleterious effects in most other organisms, however it has no apparent signs of ill health. It is also found to have extracellular Na⁺ and Cl^- levels lower than that of its environment. Given this evidence, what is this animal's method of maintaining osmotic equilibrium?

A) Osmoregulate
B) Ionoregulate
C) Ureoosmoconform
D) Homeoregualator
E) All the options listed are incorrect

Question 45

Which of the following is NOT a method of nitrogenous waste excretion in animals?

A) excretion of urea as a gas.
B) excretion of guanine in urine and/or faeces.
C) excretion of ammonia as a gas.
D) excretion of uric acid in urine and/or faeces.
E) excretion of aminopropionitrile in urine/faeces and/or as a gas.