Genes that control coat color in mammals represent some of the best early examples of genes with multiple alleles exhibiting different phenotypes. A classic example is the C gene in hamsters. Three of the known alleles of this gene are C, c^a and c^k. Each supplies a different amount of black pigment to the coat hair. The phenotypes of three different homozygous strains are as follows.

would mate the true-breeding  c^a c^a  hamsters to the true-breeding c^k c^k  hamsters to produce heterozygous  c^a and c^k  F1 progeny. Crosses and their interpretation that would have allowed geneticists to come to the conclusion that c^a and c^k were likely to be alleles of the same using the concept that alleles of the same gene will be tightly linked. What will be the ratio of F2 hamster;

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#Question id: 12056

#Unit 7. System Physiology – Animal

A 68-year-old woman with hematemesis has heartburn and stomach pain. Endoscopy shows inflammation involving the gastric body and antrum as well as a small gastric ulcer. Biopsies were positive for Helicobacter pylori. H. pylori damages the gastric mucosa primarily by increasing mucosal levels of which substance?

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#Question id: 12055

#Unit 7. System Physiology – Animal

Which of the following is a likely consequence of ileal resection?

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#Question id: 12054

#Unit 7. System Physiology – Animal

A 54-year-old woman eats a healthy meal. Approximately 20 min later the woman feels the urge to defecate. Which of the following reflexes results in the urge to defecate when the stomach is stretched?

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#Question id: 12053

#Unit 7. System Physiology – Animal

Swallowing is a complex process that involves signaling between the pharynx and swallowing center in the brainstem. Which of the following structures is critical for determining whether a bolus of food is small enough to be swallowed?

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#Question id: 12052

#Unit 7. System Physiology – Animal

Parasympathetic stimulation increases gastrointestinal motility and sympathetic stimulation decreases motility. The autonomic nervous system controls gut motility by changing which of the following?

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#Question id: 12051

#Unit 7. System Physiology – Animal

Migrating motility complexes (MMC) occur about every 90 min between meals and are thought to be stimulated by the gastrointestinal hormone, motilin. An absence of MMCs causes an increase in which of the following?