TLS Online TPP Program

#Question id: 11145


Two fundamental concepts about the ion channels of a "resting" neuron are that the channels ________.

#Unit 7. System Physiology – Animal
  1. are always open, but the concentration gradients of ions frequently change
  2. are always closed, but ions move closer to the channels during excitation
  3. are open or closed depending on their type, and are specific as to which ion can traverse them
  4. open in response to stimuli, and then close simultaneously, in unison
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TLS Online TPP Program

#Question id: 341

#Unit 1. Molecules and their Interaction Relevant to Biology

 Which force can stabilize a DNA double-helix?

TLS Online TPP Program

#Question id: 339

#Unit 1. Molecules and their Interaction Relevant to Biology

The edges of each base pair are exposed in the major and minor grooves, creating a pattern of hydrogen-bond donors and acceptors and of hydrophobic groups (allowing for Vander Waals interactions) that identifies the base pair. The edge of an C : G base pair displays the following chemical groups in the following order in the major groove:

TLS Online TPP Program

#Question id: 338

#Unit 1. Molecules and their Interaction Relevant to Biology

What is the difference between covalent bonds and ionic bonds?

TLS Online TPP Program

#Question id: 337

#Unit 1. Molecules and their Interaction Relevant to Biology

Which statement below is true about the relative lifetime of a hydrogen bond, compared to the rate of water’s ionization to hydroxide ions and hydronium ions?

TLS Online TPP Program

#Question id: 336

#Unit 1. Molecules and their Interaction Relevant to Biology

Which would you expect to be most soluble in water?

TLS Online TPP Program

#Question id: 335

#Unit 1. Molecules and their Interaction Relevant to Biology

Suppose the major solutes in intact lysosomes are KCl (~0.1 M) and NaCl (~0.03 M). When isolating lysosomes, what concentration of sucrose is required in the extracting solution at room temperature (25 °C) to prevent swelling and lysis?