TLS Online TPP Program

#Question id: 760


Which force can stabilize a DNA double-helix?

#Unit 1. Molecules and their Interaction Relevant to Biology
  1. Hydrophobic bases are found in the interior of the helix where each base pair is stabilized by the same number of hydrogen bonds.

  2. Hydrophilic sugar-phosphate groups are found on the exterior of the helix where they can interact with water.

  3. Non-covalent N-glycosidic bonds can form between nitrogenous bases in opposite strands in the helix.

  4. Covalent base-stacking interactions can occur between adjacent bases within the same strand in the helix.

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TLS Online TPP Program

#Question id: 11071

#Unit 7. System Physiology – Animal

At the end of inhalation, with an open glottis, the pleural pressure is

TLS Online TPP Program

#Question id: 11072

#Unit 7. System Physiology – Animal

The following diagram shows pulmonary airway resistance expressed as a function of pulmonary volume. Which relationship best describes the normal lung?


TLS Online TPP Program

#Question id: 11075

#Unit 7. System Physiology – Animal

A 65-year-old man with emphysema due to 34 years of cigarette smoking is admitted to hospital due to dyspnea. With further tests the mean pulmonary arterial pressure is determined to be 45 mm Hg at rest. He is hypoxic (PO2 = 49 mm Hg), hypercapnic (85 mm Hg), and slightly acidotic. The cardiovascular and oxygen changes are due to which of the following?

TLS Online TPP Program

#Question id: 11076

#Unit 7. System Physiology – Animal

Which of the following will decrease pulmonary blood flow resistance?

TLS Online TPP Program

#Question id: 11077

#Unit 7. System Physiology – Animal

A person’s normal tidal volume is 400 ml with a dead space of 100 ml. The respiratory rate is 12 breaths/min. The person is placed on ventilator for surgery and the tidal volume is 700 with a rate of 12. What is the approximate alveolar Pco2 for this person?

TLS Online TPP Program

#Question id: 11079

#Unit 7. System Physiology – Animal

The diffusing capacity of a gas is the volume of gas that will diffuse through a membrane each minute for a pressure difference of 1 mm Hg. Which of the following gases is often used to estimate the oxygen diffusing capacity of the lungs?