Final #2

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An antigen _____.

a) is a protein molecule that helps defend the body against disease

b) is a foreign molecule that evokes a specific response by a lymphocyte

c) could be an invading bacterium

d) induces development of white blood cells in the bone marrow

e) is a protein attacked by an invading microorganism



The fact that there are about a million different antigen receptors possible in human B cells is based on _____.

a) temporary changes in the ways that RNA is spliced in the B cells

b) recombination of the segments of the receptor DNA that make up the functional receptor genes of differentiated B cells

c) constant changes in the splicing pattern of receptor genes after the differentiation of the B cell

d) having one million different immunoglobulin genes

e) the capacity of memory cells to produce antibodies



Within a differentiated B cell, the rearrangement of DNA sequences between variable regions and joining regions is accomplished by a(n)_____.

a) epitopase

b) RNA polymerase

c) reverse transcriptase

d) recombinase



Clonal selection and differentiation of B cells activated by antigen exposure leads to the production of _____.

a) large quantities of the antigen initially recognized

b) long-lived erythrocytes that can later secrete antibodies for the antigen

c) vast numbers of B cells with random antigen-recognition receptors

d) short-lived plasma cells that secrete antibodies for the antigen



A newborn who is accidentally given a drug that destroys the thymus would most likely _____.

a) have a reduced number of B cells and be unable to form antibodies

b) be unable to differentiate and mature T cells

c) be unable to genetically rearrange antigen receptor

d) slack innate immunity



Clonal selection is an explanation for how _____.

a) an antigen can provoke production of high levels of specific antibodies

b) HIV (human immunodeficiency virus) can disrupt the immune system

c) V, J, and C gene segments are rearranged

d) macrophages can recognize specific T cells and B cells



An immunoglobulin (Ig) molecule, of whatever class, with regions symbolized as C or V, H or L, has a light chain made up of _____.

a) two C regions and two V regions

b) one H region and one L region

c) three H regions and one L region

d) one C region and one V region



Immunological memory accounts for _____.

a) the ability of a helper T cell to signal B cells via cytokines

b) the observation that some strains of the pathogen that causes dengue fever cause more severe disease than others

c) the human body's ability to distinguish self from non-self

d) the ancient observation that someone who had recovered from the plague could safely care for those newly diseased



Use the following information to answer the question(s) below.

An otherwise healthy student in your class is infected with EBV, the virus that causes infectious mononucleosis. The same student had already been infected when she was a child, at which time she had merely experienced a mild sore throat and swollen lymph nodes in her neck. This time, though infected, she does not get sick.

The EBV antigen fragments will be presented by the virus-infected cells along with _____.

a) class I MHC molecules

b) antibodies

c) a complement

d) class II MHC molecules



Vaccination increases the number of _____.

a) major histocompatability (MHC) molecules that can present an antigen

b) lymphocytes with receptors that can bind to the pathogen

c) epitopes that the immune system can recognize

d) macrophages specific for a pathogen



If a patient is missing B and T cells, what would be absent from the immune response?

a) cytokines

b) memory

c) defense against bacteria

d) lysozymes



Lymphocytes mature in the _____.
I) spleen
II) thymus
III) bone marrow

a) only II and III

b) only I and III

c) only I and II

d) I, II, and III



Which of the following statements are fundamental to the clonal-selection theory of how the adaptive immune system functions?
I) Each lymphocyte has a unique membrane receptor that recognizes one antigen.
II) When the lymphocyte binds an antigen, it is activated and begins dividing to form many identical copies of itself.
III) Cloned lymphocytes have slight differences and are selected by the spleen for removal if they do not bind an antigen.
IV) Cloned cells descend from an activated lymphocyte and persist even after the pathogen is eliminated.

a) only I and III

b) only I, II, and IV

c) only II, III, and IV

d) only II and IV



What major advantage is conveyed by having a system of adaptive immunity?

a) It results in effector cells with specificity for a large number of antigens.

b) It enables an animal to counter most pathogens almost instantly the first time they are encountered.

c) It allows for the destruction of antibodies.

d) It enables a rapid defense against an antigen that has been previously encountered.



Which of the following is a difference between B cells and T cells?

a) T cells are produced in the thymus and B cells are produced in the bone marrow.

b) One binds a receptor called BCR (B-cell receptor), while the other recognizes a receptor called TCR (T-cell receptor).

c) One has a major role in antibody production, while the other has a major role in cytotoxicity.

d) B cells are activated by free-floating antigens in the blood or lymph. T cells are activated by membrane-bound antigens.



A certain cell type has existed in the blood and tissue of its vertebrate host's immune system for over twenty years. One day, it recognizes a newly arrived antigen and binds to it, subsequently triggering a secondary immune response in the body. Which of the following cell types most accurately describes this cell?

a) plasma cell

b) macrophage

c) memory cell

d) thyroid cell



Which of the following statements about epitopes are correct?
I) B-cell receptors bind to epitopes.
II) T-cell receptors bind to epitopes.
III) There can be 10 or more different epitopes on each antigen.
IV) There is a one-to-one correspondence between antigen and epitope.

a) only I and III

b) only I, II, and III

c) only II, III, and IV

d) only II and IV



Which of the following pairs of proteins shares the most overall similarity in structure?

a) B-cell receptors and T-cell receptors

b) B-cell receptors and antibodies

c) T-cell receptors and antibodies

d) antibodies and antigens



The words “antigen” and “virus” are interchangeable.

a) true

b) false



A man who has been exposed to the flu virus is tested by his physician. The physician notes that the virus is present but no measurable level of antibodies corresponding to the virus are detected in his body. What might this mean?

a) He was probably exposed more than several months ago, antibody production has ceased, and antibodies are no longer detectable.

b) He was probably exposed sometime within the past two weeks, but we don’t have enough information to say more.

c) He was probably exposed a few days ago and clonal selection has yet to produce plasma cells.



Which is a true statement about memory cells?

a) The first time an antigen is encountered, memory cells become plasma cells.

b) They engulf antigens bound by antibodies.

c) They produce antibodies.

d) They have a longer lifespan than plasma cells.



Which of these cells is a phagocytic leukocyte that can engulf a foreign bacterium?

a) plasma cell

b) cytotoxic T cell

c) helper T cell

d)B cell

e) macrophage



_____ interact with the antigen-class II MHC complex presented by macrophages.

a) B cells

b) Epithelial cells

c) Helper T cells

d) Bacterial cells

e) Cytotoxic T cells



B cells that have been stimulated by interleukin-2 develop into _____.

a) antigens

b) helper T cells

c) plasma cells

d) macrophages

e) cytotoxic T cells



The role of cytotoxic T cells is the secretion of _____, which plays a role in the _____ immune response.

a) antibodies ... antibody-mediated

b) interleukin-2 ... humoral

c) perforin ... humoral

d) antibodies ... humoral

e) perforin ... cell-mediated



Clonal selection is the division of _____ that have been stimulated by binding to an antigen, which results in the production of cloned _____.

a) helper T cells ... plasma cells

b) B cells ... macrophages

c) B cells ... plasma cells and memory cells

d) T cells ... B cells

e) macrophages ... B cells and T cells



Which of these cells is responsible for the rapidity of the secondary immune response?

a) cytotoxic T cells

b) plasma cells

c) memory cells

d) macrophages

e) cytokines



Which of these cells produce and secrete antibodies?

a) plasma cells

b) helper T cells

c) macrophages

d) bacterial cells

e) cytotoxic T cells



The role of active cytotoxic T cells is to attack _____.

a) circulating antibodies

b) body cells that have been infected

c) circulating proteins

d) extracellular viruses and bacteria

e) complement proteins



Cell-mediated immunity differs from humoral immunity in that _____.

a) clonal selection occurs only in cell-mediated immunity

b) they respond differently to invaders

c) cell-mediated immunity is longer lasting

d) a subsequent secondary immune response can occur in humoral immunity

e) a humoral response is mounted more quickly



Helper T cells are part of _____.

a) cell-mediated immune responses

b) innate immunity

c) the complement system

d) a group of phagocytic white blood cells

e) the first cells to bind to antigens



Extracellular pathogens such as viruses and bacteria in body fluids are attacked by _____.

a) antibodies from plasma cells

b) helper T cells

c) complement proteins

d) antigens

e) cytotoxic T cells



Tissues are immunogically "typed" before an organ transplant to make sure that the donor and recipient match as closely as possible in their _____.

a) MHC (major histocompatibility complex) proteins

b) B cells

c) histamines

d) antibodies

e) T cells



What type of immunity is associated with breast feeding?

a) innate immunity

b) active immunity

c) cell-mediated immunity

d) passive immunity



Arrange in the correct sequence these components of the mammalian immune system as it first responds to a pathogen.
I) Pathogen is destroyed.
II) Lymphocytes secrete antibodies.
III) Antigenic determinants from pathogen bind to antigen receptors on lymphocytes.
IV) Lymphocytes specific to antigenic determinants from pathogen become numerous.
V) Only memory cells remain.

a) III → IV → II → I → V

b) II → I → IV → III → V

c) IV → II → III → I → V

d) I → III → II → IV → V



When antibodies bind antigens, the clumping of antigens results from _____.

a) denaturation of the antibodies

b) disulfide bridges between the antigens

c) bonds between class I and class II MHC molecules

d) the antibody having at least two binding regions



Naturally acquired passive immunity can result from the _____.

a) ingestion of interferon

b) placental transfer of antibodies

c) injection of vaccine

d) absorption of pathogens through mucous membranes



Jenner's successful use of cowpox virus as a vaccine against the smallpox virus was due to the fact that _____.

a) the immune system responds nonspecifically to antigens

b) cowpox and smallpox are caused by the same virus

c) there are some epitopes (antigenic determinants) common to both pox viruses

d) the cowpox virus made antibodies in response to the presence of smallpox



An individual who has been bitten by a poisonous snake that has a fast-acting toxin would likely benefit from _____.

a) vaccination with a weakened form of the toxin

b) injection of antibodies to the toxin

c) injection of interleukin-1

d) injection of interferon



For the successful development of a vaccine to be used against a pathogen, it is necessary that _____.

a) the pathogen has only one epitope

b) the surface antigens of the pathogen stay the same

c) all of the surface antigens on the pathogen be identified

d) the major histocompatability (MHC) molecules are heterozygous



The switch of one B cell from producing one class of antibody to another class of antibody that is responsive to the same antigen is due to _____.

a) the rearrangement of V region genes in that clone of responsive B cells

b) a patient's reaction to the first kind of antibody made by the plasma cells

c) the rearrangement of immunoglobulin heavy-chain C region DNA

d) a switch in the kind of antigen-presenting cell that is involved in the immune response



Which of the following should be the same in identical twins?

a) the susceptibility to a particular virus

b) the set of antibodies produced

c) the set of major histocompatability (MHC) molecules produced

d) the set of T cell antigen receptors produced



Which of the following components of the immune system destroys bacteria in a way similar to an antitank weapon destroying armored military tanks by punching holes in the wall of the bacteria?

a) macrophages

b) plasma cells

c) major histocompatibility complex proteins

d) complement protein



A primary reason for needing a new vaccine for influenza each year is that _____.

a) the influenza virus might proliferate in different tissues during each subsequent year, and immune memory is limited to those tissues initially infected

b) mutation in the influenza virus is frequent

c) the first infection with influenza weakens the immune system

d) influenza is a disease that causes the apoptosis of all memory cells

e) immunity typically disappears one month after recovery from a disease



Yearly vaccination of humans for influenza viruses is necessary because _____.

a) of an increase in immunodeficiency diseases

b) surviving the flu one year exhausts the immune system to nonresponsiveness the second year

c) rapid mutation in flu viruses alters the surface proteins in infected host cells

d) the flu can generate anaphylactic shock



Each person makes more than 1 million different B cell antigen receptors and more than 10 million different T cell antigen receptors. How is such diversity in antigen receptors generated?

a) By combining variable elements, the immune system assembles many different receptors from a much smaller collection of parts.

b) Genes for individual antigen-binding sites have a very high rate of mutation, generating great diversity.

c) A large percentage of the vertebrate genome is devoted to genes for individual antigen-binding sites.



What is the role of recombinase in generating lymphocyte diversity?

a) Early in B cell development, recombinase links one light-chain V gene segment to one Jgene segment.

b) Recombinase combines DNA from human and viral origin.

c) Recombinase splices RNA to produce variable transcripts.



Select the correct statement about the immune system.

a) All antigen receptors produced by a single B cell or T cell are identical and bind to the same epitope.

b) Adaptive immunity is characteristic of invertebrates and vertebrates.

c) Antibodies are secreted by T cells.



How does an antihistamine reduce allergy symptoms?

a) An antihistamine kills mast cells, blocking an allergic reaction.

b) An antihistamine blocks receptors for inflammatory chemicals released from granules within mast cells.

c) An antihistamine binds pollen antigens, preventing them from provoking an allergic reaction.



Because antigen receptor genes are randomly rearranged, some immature lymphocytes produce receptors specific for epitopes on the organism’s own molecules. Why doesn’t the immune system attack these molecules on the body’s cells and tissues?

a) The body’s cells are immune to such attack.

b) Only a very few lymphocytes produce receptors that attack the body’s own molecules, so it’s not a problem.

c) B and T cells with receptors specific for the body’s own molecules are destroyed by apoptosis.



Osmoregulation and excretion are _____.

a) ways that animals control their external environment

b) mechanisms that require continual water loss

c) chemical processes that completely stop during torpor and hibernation

d) mechanisms that maintain volume and composition of body fluids

e) mechanisms for the homeostatic control of body temperature



The force driving simple diffusion is _____, while the energy source for active transport is _____.

a) phosphorylated protein carriers; ATP

b) the concentration gradient; ATP

c) transmembrane pumps; electron transport

d) the concentration gradient; ADP



The body fluids of an osmoconformer would be _____ with its _____ environment

a) hypoosmotic; saltwater

b) isoosmotic; saltwater

c) isoosmotic; freshwater

d) hyperosmotic; saltwater



Compared to the seawater around them, most marine invertebrates are _____.

a) hypoosmotic

b) isoosmotic

c) hyperosmotic and isoosmotic

d) hyperosmotic



The fluid with the highest osmolarity is _____.

a) plasma in birds

b) distilled water

c) plasma in mammals

d) seawater in a tidal pool



A human who has no access to fresh water but is forced to drink seawater instead will _____.

a) develop structural changes in the kidneys to accommodate the salt overload

b) thrive under such conditions, as long as he has lived at the ocean most of his life

c) risk becoming overhydrated within twelve hours

d) excrete more water molecules than taken in, because of the high load of ion ingestion



Which of the following animals generally has the lowest volume of urine production?

a) a marine bony fish

b) a salmon in fresh water

c) a vampire bat

d) a shark inhabiting the Mississippi River



Birds, insects, and many reptiles excrete nitrogenous waste in the form of uric acid, which _____.

a) reduces water loss compared to other nitrogenous wastes, but requires more metabolic energy to produce

b) reduces energy use compared to other nitrogenous wastes, but is highly toxic to animals that produce it

c) reduces water loss compared to other nitrogenous wastes, but is highly toxic

d) is not very toxic compared to other nitrogenous wastes, but requires the loss of a lot of water with its excretion

e) is much more soluble in water than other nitrogenous wastes, but is energetically costlier than other nitrogenous wastes to synthesize



Freshwater fish excrete nitrogenous wastes as _____.

a) urea

b) proteins

c) guano

d) ammonia

e) uric acid



One of the waste products that accumulates during cellular functions is carbon dioxide. It is removed via the respiratory system. What is another waste product that accumulates during normal physiological functions in vertebrates?
I) ammonia
II) uric acid
III) urea

a) only I and III

b) only I and II

c) I, II, and III

d) only II and III



Urea is produced in the _____.

a) bladder from uric acid and water

b) kidneys from glycerol and fatty acids

c) liver from glycogen

d) liver from NH3 and carbon dioxide



Urea is _____.

a) insoluble in water

b) the primary nitrogenous waste product of most aquatic invertebrates

c) the primary nitrogenous waste product of humans

d) the primary nitrogenous waste product of most birds



Which nitrogenous waste has the greatest number of nitrogen atoms?

a) ammonia

b) uric acid

c) urea

d) ammonium ions



Ammonia is likely to be the primary nitrogenous waste in living conditions that include _____.

a) lots of seawater, such as a bird living in a marine environment

b) a moist system of burrows, such as those of naked mole rats

c) a terrestrial environment, such as that supporting crickets

d) lots of fresh water flowing across the gills of a fish



Excessive formation of uric acid crystals in humans leads to _____.

a) a condition of insatiable thirst and excessive urine formation

b) gout, a painful inflammatory disease that primarily affects the joints

c) osteoarthritis, an inevitable consequence of aging

d) a condition called diabetes, where excessive urine formation occurs



Ammonia _____.

a) is soluble in water

b) is the major nitrogenous waste excreted by insects

c) has low toxicity relative to urea

d) is metabolically more expensive to synthesize than urea



The advantage of excreting nitrogenous wastes as urea rather than as ammonia is that _____.

a) less nitrogen is removed from the body

b) urea is less toxic than ammonia

c) urea can be exchanged for Na+

d) urea does not affect the osmolar gradient



In animals, nitrogenous wastes are produced mostly from the catabolism of _____.

a) starch and cellulose

b) triglycerides and steroids

c) phospholipids and glycolipids

d) proteins and nucleic acids



Birds secrete uric acid as their nitrogenous waste because uric acid _____.

a) can be reused by birds as a protein source

b) requires little water for nitrogenous waste disposal, thus reducing body mass

c) is readily soluble in water

d) is metabolically less expensive to synthesize than other excretory products



Among the following choices, the most concentrated urine is excreted by _____.

a) humans

b) frogs

c) kangaroo rats

d) freshwater bass



Urine formed by a kidney collects in the _____ before being drained from the kidney by the _____ and transported to the _____.

a) urethra ... urinary bladder ... ureter

b) renal pelvis ... medulla ... cortex

c) renal pelvis ... ureter ...urinary bladder

d) renal pelvis ... urethra ... urinary bladder

e) ureter ... renal pelvis ... urinary bladder



The _____ are the major blood vessels transporting blood to the kidneys.

a) pulmonary arteries

b) glomerulus

c) renal arteries

d) renal veins

e) venae cavae



The outer part of the kidney is the _____.

a) medulla

b) nephron

c) lacteal

d) cortex

e) Bowman's capsule



Which of these is the functional unit of a kidney?

a) neuron

b) villi

c) nephron

d) alveolus

e) osteon



Which of the following most accurately describes selective permeability?

a) Lipid-soluble molecules pass through a membrane.

b) An input of energy is required for transport.

c) Only certain molecules can cross a cell membrane.

d) There must be a concentration gradient for molecules to pass through a membrane.



Why are the renal artery and vein critical to the process of osmoregulation in vertebrates?

a) The renal artery delivers blood with nitrogenous waste to the kidney and the renal vein brings blood with less nitrogenous wastes away from the kidneys.

b) The renal artery and vein are the main pathways regulating how much is produced by the kidneys.

c) The kidneys require constant and abnormally high oxygen supply to function.

d) The kidneys require higher than normal levels of hormones.



Materials are returned to the blood from the filtrate by which of the following processes?a) excretion

b) filtration

c) selective reabsorption

d) secretion



The osmoregulatory process called secretion refers to the _____.

a) expulsion of urine from the body

b) selective elimination of excess ions and toxins from body fluids

c) formation of an osmotic gradient along an excretory structure

d) reabsorption of nutrients from a filtrate



An excretory system that is partly based on the filtration of fluid under high hydrostatic pressure is the _____.

a) flame bulb system of flatworms

b) kidneys of vertebrates

c) Malpighian tubules of insects

d) protonephridia of rotifers



The transfer of fluid from the glomerulus to Bowman's capsule _____.

a) results from active transport

b) transfers large molecules as easily as small ones

c) is very selective as to which subprotein-sized molecules are transferred

d) is mainly a consequence of blood pressure in the capillaries of the glomerulus



Within a normally functioning kidney, blood can be found in _____.

a) Bowman's capsule

b) the proximal tubule

c) the collecting duct

d) the vasa recta



A primary reason that the kidneys have one of the highest metabolic rates of all body organs is that _____.

a) they have membranes of varying permeability to water

b) they operate an extensive set of active-transport ion pumps

c) they have an abundance of myogenic smooth muscle

d) they are the body's only means of shedding excess nutrients



Which process in the nephron is LEAST selective?

a) reabsorption

b) filtration

c) active transport

d) secretion



The movement of substances out of the glomerulus and into Bowman's capsule is referred to as _____.

a) secretion

b) reabsorption

c) active transport

d) ion pumping

e) filtration



The movement of substances from the blood into the proximal tubule is known as _____.

a) filtration

b) dialysis

c) secretion

d) reabsorption

e) none of these



Which of these is reabsorbed from filtrate?

a) sodium chloride

b) glucose

c) water

d) amino acids

e) all of these



As filtrate moves down the loop of Henle, the surrounding interstitial fluid becomes _____ concentrated than the filtrate, so _____ leaves the filtrate.

a) more ... urea

b) less ... urea

c) more ... water

d) less ... water

e) less ... water and urea



The most abundant solute in urine is _____.

a) glucose

b) water

c) plasma proteins

d) sodium chloride

e) urea (and other nitrogenous wastes)



Glucose is removed from filtrate by _____.

a) secretion

b) diffusion

c) dialysis

d) active transport

e) osmosis



As a result of the non-selectivity of the kidney's filtration of small molecules, _____.

a) urine is always much less concentrated than blood

b) many useful substances are lost in the urine

c) the proportions of all the substances in the blood are the same as in the urine

d) the kidneys have little control over body fluid composition

e) useful substances must be selectively reabsorbed



What is the function of the osmotic gradient found in the kidney? The osmotic gradient allows for _____.

a) electrolytes to move from low to high concentrations in the absence of ATP

b) the filtration of large cells at the glomerulus

c) the loop of Henle to deliver water to the renal vein

d) the precise control of the retention of water and electrolytes



The loop of Henle dips into the renal cortex. This is an important feature of osmoregulation in terrestrial vertebrates because _____.

a) additional filtration takes place along the loop of Henle

b) differential permeabilities of ascending and descending limbs of the loop of Henle are important in establishing an osmotic gradient

c) absorptive processes taking place in the loop of Henle are hormonally regulated

d) the loop of Henle plays an important role in detoxification



Low selectivity of solute movement is a characteristic of _____.

a) reabsorption mechanisms along the proximal tubule

b) H+ pumping to control pH

c) secretion along the distal tubule

d) filtration from the glomerular capillaries



If ATP production in a human kidney was suddenly halted, urine production would _____.

a) decrease, and the urine would be isoosmotic compared to plasma

b) decrease, and the urine would be hypoosmotic compared to plasma

c) increase, and the urine would be isoosmotic compared to plasma

d) increase, and the urine would be hyperosmotic compared to plasma



Compared to wetland mammals, water conservation in mammals of arid regions is enhanced by having more _____.

a) podocytes

b) urinary bladders

c) ureters

d) juxtamedullary nephrons



Processing of filtrate in the proximal and distal tubules _____.

a) achieves the conversion of toxic ammonia to less toxic urea

b) regulates the speed of blood flow through the nephrons

c) reabsorbs urea to maintain osmotic balance

d) maintains homeostasis of pH in body fluids



In humans, the transport epithelial cells in the ascending loop of Henle _____.

a) are not affected by high levels of nitrogenous wastes

b) are not in contact with interstitial fluid

c) have plasma membranes of low permeability to water

d) are the largest epithelial cells in the body



Natural selection should favor the highest proportion of juxtamedullary nephrons in which of the following species?

a) a mouse species living in a desert

b) a river otter

c) a mouse species living in a temperate broadleaf forest

d) a mouse species living in a tropical rain forest



The structural component(s) of the mammalian nephron where the transcytosis of water increases due to the action of anti-diuretic hormone is/are the _____.

a) glomeruli

b) afferent and efferent arterioles

c) collecting duct

d) Bowman's capsulesnephrons



Aldosterone is _____.

a) a steroid hormone that reduces the amount of fluid excreted in the urine

b) a protein hormone that decreases blood pressure without changing blood volume

c) is released in great quantities when ethanol intoxication takes place

d) triggers the conversion of angiotensinogen into angiotensin II

e) decreases water reabsorption in the kidneys



If you are hiking through the desert for several days, one would pack which of the following to ensure proper hydration?

a) bottled water that had been frozen to ensure that it would be as cold as possible

b) bottled water kept at room temperature

c) a drink with a combination of water and electrolytes

d) caffeinated beverages



Increased antidiuretic hormone (ADH) secretion is likely after _____.

a) eating a small sugary snack

b) sweating-induced dehydration increases plasma osmolarity

c) drinking lots of pure water

d) blood pressure becomes abnormally high



Select the correct statement about osmolarity.

a) The contents of an animal cell are hyperosmotic.

b) If two solutions are separated by a selectively permeable membrane, water flows by osmosis from a hyperosmotic solution to a hypoosmotic one.

c) Osmolarity measures the moles of solute per liter of solution.



Select the correct statement about osmoregulation.

a) The less the gradient between an animal’s internal osmolarity and its external osmolarity (that of its surroundings), the higher the cost of osmoregulation.

b) All osmoconformers are marine animals.

c) All marine invertebrates are stenohaline.



Select the correct statement describing the osmolarity of mammalian urine.

a) Mammalian urine is always hyperosmotic to blood.

b) The osmolarity of mammalian urine varies little between species

c) The osmolarity of mammalian urine may vary over time.