Deck 59: Digestion and Absorption of the Macronutrients

Question 1

Uptake of dipeptides across the brush border mem brane

A) Does not occur
B) Oc curs through a secondary active transport mechanism by using a H+ cotransporter
C) Uses a facilitated diffusion mechanism
D) Requ ires mu ltiple carrier types to recog nize the diversity of dipeptide form s
E) Occurs only in the ileum

Answer 1

B

Question 2

The gre ates t incre ase in sur fac e are a for abs orptio n is du e to

A) Folds of Kerckring
B) Villus
C) Central lacteal
D) M icro villi
E) Basolateral mem brane

Answer 2

D

Question 3

In th e in tes tine , fru cto se is

A) A product of sucrose digestion
B) Actively transported across the brush border mem brane
C) Taken up by active transport mechanism
D) Transported across the brush border by a Na+-cotransport mechanism
E) Both A and C are correct

Answer 3

A

Question 4

Transfer of single amino acids from the enterocyte to the blood occurs by

A) Facilitated diffusion
B) Prim ary ac tive tran spo rt
C) Secondary active transport linked to Na+ cotra nsp ort
D) Secondary active transport linked to H+ cotransport
E) Both A and C

Question 5

Endopeptidases include which of the following?

A) Try ps in
B) Carboxypeptidase
C) Dipeptidylcarboxypeptidase
D) Dipeptidylaminopeptidase
E) Am inopeptidase

Question 6

Premature activation of pancreatic proteolytic enzymes is prevented by

A) Syn thes is as ina ctive p recu rsors
B) Sequestration away from activator Ca₂+
C) Enterokinase inhibitor
D) Inhibitory amino acids within the secretory granules
E) Concentration of the enzyme in the granules

Question 7

Pancreatic amylase

A) Breaks starch down to glucose
B) Breaks unbranched starch down com pletely to maltose and maltotriose
C) Breaks branched starch down completely to maltose and maltotriose
D) Releases limit dextrins from unbranched starches
E) Releases glucose from starch

Question 8

Am ino acids are absorbed

A) Only as single amino acids
B) Only as dipeptides
C) As both single amino acids and dipeptides
D) Mainly as oligopeptides
E) Only by be ing co-transported with Na+

Question 9

Pespsinogen is activated to pepsin by

A) Sto m ach acid
B) Enterokinase
C) T ryp sin
D) C hym otr yps in
E) Se cr etin

Question 10

The ga stric p has e of p rotein diges tion is du e to

A) T ryp sin
B) C hr ym otr yps in
C) Pe ps in
D) Carboxypeptidase
E) Am inopeptidase

Question 11

The brush border enzymes involved in protein digestion include all of the following EXCEPT

A) Carboxypeptidase A
B) Am inopeptidase N
C) Am inopeptidase A
D) Dipeptidylcarboxypeptidase
E) Dipeptidylaminopeptidase

Question 12

Glucose uptake across the brush border is by

A) Facilitated diffusion
B) Prim ary ac tive tran spo rt
C) Secondary active transport linked to Na+ cotra nsp ort
D) Secondary active transport linked to H+ cotransport
E) Both A and C are correct

Question 13

Am ino acid absorption across the brush border mem brane

A) Uses both Na+-am ino acid cotransport and faciliitated diffusion mechanisms
B) Alwa ys requires direct hydrolysis of ATP
C) Requires Na+ co-transport in all cases
D) Cannot accomm odate dipeptides
E) Mainly transports dipeptides

Question 14

Hum ans cannot digest cellulose because

A) Hum ans lack enzymes to split the a (1,4) glycosidic linkage in cellulose
B) Hum ans lack enzymes to split the a (1,6) glycosidic linkage in cellulose
C) Adult humans lack lactase
D) Hum ans cannot split the þ 1,4 glycosidic linkage in cellulose
E) Hum ans lack amylase

Question 15

Activation of pancreatic proteolytic enzymes is achieved by

A) Enterokinase within the zymogen granules
B) Trypsin activator on the intestinal brush border
C) Trypsin activator in the intestinal lumen
D) Enterokinase on the intestinal brush border
E) Ca₂+ in th e b ile

Question 16

Which of the followin g sta tem ents abo ut lacta se is NO T tru e?

A) Adult lack of lactase is present in most populations except Northern Europeans
B) Lactase is necessary for the hydrolysis of lactose
C) Lactose is composed of galactose and glucose
D) Lactase deficiency causes lactose intolerance
E) Persons with lactase can eat any amount of lactose w ithout symptoms

Question 17

W hat other sugar competitively inhibits glucose uptake at the brush border mem brane?

A) Fructose
B) Sucrose
C) Galactose
D) Lactose
E) Ribose

Question 18

Sugars are taken up by enterocytes

A) Mainly as disaccharides
B) Only as glucose
C) Only by facilitated diffusion
D) Only by secondary active transport
E) Only as monosaccharides

Question 19

Galactose is liberated on the brush border by

A) Isomaltase action on sucrose
B) Sucrase action on sucrose
C) Lactase action on lactose
D) Dextrinase action on starch
E) Am ylase action on starch

Question 20

G luc os e tr an sf er fro m the en ter oc yte to the blo od oc cu rs by

A) Facilitated diffusion
B) Prim ary ac tive tran spo rt
C) Secondary active transport linked to Na+ cotransport
D) Secondary active transport linked to H+ cotransport
E) Both A and C

Question 21

Pancreatic lipase

A) Hydrolyzes triglycerides to fatty acids and 2-monoglyceride
B) Hydrolyzes phospholipids to fatty acids and lysophospholipids
C) Hydrolyzes cholesterol esters to fatty acids and cholesterol
D) Cleaves off choline from phospholipids to produce phosphatidic acid and choline
E) Hydrolyzes 2-monoglycerides to glycerol and fatty acids

Question 22

Triglyerides in the lymph or portal blood are

A) Re-esterified from absorbed fatty acids and glycerol in the enterocyte cytosol
B) Absorbed intact from the intestinal lumen
C) Synthesized from acteyl CoA and glycerol in the enterocyte smooth ER
D) Re-esterified from absorbed fatty acids and glycerol in the enterocyte smooth ER
E) Packaged mainly in VHDL

Question 23

The surface activity of bile acids

A) Depends primarily on the free carboxyl group
B) Incr eas es w ith th e nu m be r of h ydro xyl g rou ps on the bile a cid
C) Requires conjugation of the free carboxyl group with taurine or glycine
D) Is not required for the formation of mixed micelles
E) Anchors phospholipase A2 to lipid droplets in the lumen

Question 24

Lactose intolerance is accompanied by all of the following EXCEPT

A) Osm otic diarrhea
B) Increased H₂ in th e e xh ale d a ir
C) Intestinal bloating and cramps
D) Increased intestinal gas
E) Decrea sed G I motility

Question 25

Lipoproteins are

A) Proteins with lipid covalently attached
B) Proteins that coat lipids to solubilize them
C) Lip ids wh os e c ar bo xyl g ro up s f or m a p ep tide bo nd with an am ino ac id
D) M acom olecular ass em blies of lipids w ith apolipo protein co ats
E) Made in the intestinal lumen

Question 26

The m ain fun ctio n o f bile ac ids is d ue to th eir

A) Solub ilizing ac tion on fats and fat d igestion p rodu cts
B) Enterohepatic circulation
C) Activation of phospholipase A2
D) Content of cholesterol
E) Hydrolysis of triglycerides

Question 27

In mixed micelles

A) Triglycerides occupy the surface
B) Bile acids coat the surface with the hydroxyl groups facing the water phase
C) Glycerol coats the surface
D) Lysolecithin is the main surface active component
E) The shape o f the m icelle is a hollow sphere

Question 28

Which of the following is not found on the brush border mem brane?

A) SGLT1
B) GLUT5
C) GLUT2
D) Am inopeptidase
E) Sucrase

Question 29

Activation of pancreatic lipase requires

A) Bile acids
B) Phospholipase A2
C) Pancreatic co-lipase
D) Bile pigm ents
E) Both A and C are correct

Question 30

Long chain fatty acids are mainly transported in the

A) Lymph as VLDL
B) Portal blood as HDL
C) Lymph as chylomicrons
D) Portal blood as chylomicrons
E) Both A and C are correct