TLS Online TPP Program

#Question id: 806


A single-stranded DNA molecule contains 40 nucleotides with equal amounts of A, C, G, and T. This DNA strand can combine with a complementary DNA strand to form a double-stranded DNA molecule. Which characteristic does this double-stranded molecule have when it forms a B-DNA structure?

#Unit 1. Molecules and their Interaction Relevant to Biology
  1. The two strands will have parallel orientation and identical sequences.

  2. The helix will be right-handed with 12 base-pairs per turn.

  3. Every base-pair will contain one purine and one pyrimidine.

  4. There are both covalent and non-covalent bonds between the two chains.

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TLS Online TPP Program

#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?

TLS Online TPP Program

#Question id: 12055

#Unit 7. System Physiology – Animal

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

TLS Online TPP Program

#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?

TLS Online TPP Program

#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?

TLS Online TPP Program

#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?

TLS Online TPP Program

#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?