Wild type E. coli metabolizes the sugar lactose by expressing the enzyme ß-galactosidase. You have isolated a mutant that you call lac1–, which cannot synthesize ß-galactosidase and cannot grow on lactose (Lac–). During an condition Lac– strain, called lac3–, is linked to the Tn5 insertion. From a strain carrying the Tn5 insertion and lac3– mutation you isolate an F’ that caries a region of the chromosome that includes both Tn5 and the linked Lac region. Introduce this F’ into an F– strain carrying lac1– by selecting for Kanr. These merodiploids express ß-galactosidase normally. If the merodiploid were Lac–, 

a) the two mutations lie in the different gene.

b) Both mutation are complement each other

c) the two mutations lie in the same gene.

d) Both of the mutations is dominant to wild type.

what could you conclude about the relationship between the lac3– and lac1– mutations from  these statements?

TLS Online TPP Program

#Question id: 12213

#Unit 7. System Physiology – Animal

The gastric phase of gastric secretion accounts for about 60% of the acid response to a meal. Which of the following can virtually eliminate the secretion of acid during the gastric phase?

TLS Online TPP Program

#Question id: 12214

#Unit 7. System Physiology – Animal

A 53-year-old man with a recurrent history of ulcer disease associated with diarrhea and a strong family history of duodenal ulcer disease is suspected of having Zollinger-Ellison syndrome (gastrinoma). Secretin (2 units/kg) was given as a rapid intravenous injection to test for gastrinoma. Which of the following results would support the existence of gastrinoma following secretin administration?

TLS Online TPP Program

#Question id: 12215

#Unit 7. System Physiology – Animal

Damage to the gastric mucosal barrier is a forerunner of gastric ulcer. Which of the following can both damage the gastric mucosal barrier and stimulate gastric acid secretion?

TLS Online TPP Program

#Question id: 12216

#Unit 7. System Physiology – Animal

Gastric emptying is regulated to ensure the chyme enters the duodenum at an appropriate rate. Which of the following factors promotes gastric emptying?

TLS Online TPP Program

#Question id: 12217

#Unit 7. System Physiology – Animal

Cystic fibrosis is the most common cause of pancreatitis in children. Which of the following best explains the mechanism of cystic fibrosis–induced pancreatitis?

TLS Online TPP Program

#Question id: 12218

#Unit 7. System Physiology – Animal

The control of gastric acid secretion in response to a meal involves several events that take place over a 4- or 5-hr period following the meal. These events include

(1) a decrease in the pH of the gastric contents,

(2) an increase in the rate of acid secretion,

(3) a decrease in the rate of acid secretion, and

(4) an increase in the pH of the gastric contents. Which of the following best describes

the correct temporal order of events over a 4- or 5-hr period following a meal?