Following statements are regarding to cotransport.

A. The two forces constituting the electrochemical gradient—the membrane electric potential and the ion concentration gradient—may act in the same or opposite directions.

B. Cotransporters use the energy released by movement of an ion (usually H+ or Na+) down its electrochemical gradient to power the import or export of a small molecule or different ion against its concentration gradient.

C. Cotransporters use the energy released by movement of an ion (usually H+ or Na+) down its electrochemical gradient to power the import or export of a small molecule or different ion down its concentration gradient.

D. The cells lining the small intestine and kidney tubules contain symporters that couple the energetically favorable entry of Na+ to the import of glucose against its concentration gradient.

Which of the following is incorrect?

#Question id: 399

#Unit 1. Molecules and their Interaction Relevant to Biology

Calculate the pH of a 1 L solution containing 0.100 M formic acid and 0.100 M sodium formate before and after the addition of 1.00 mL of 5.00 M NaOH. How much would the pH change if the NaOH were added to 1.00 L of pure water? (pKa for formic acid is 3.75)

#Question id: 398

#Unit 1. Molecules and their Interaction Relevant to Biology

One of the buffers that contribute to pH stability in human blood is carbonic acid (H2CO3). Carbonic acid is a weak acid that, when placed in an aqueous solution, dissociates into a bicarbonate ion (HCO3-) and a hydrogen ion (H+). (See figure.)

If the pH of blood drops, one would expect ________.

#Question id: 397

#Unit 1. Molecules and their Interaction Relevant to Biology

The loss of water from a plant by transpiration cools the leaf. Movement of water in transpiration requires both adhesion to the conducting walls and wood fibers of the plant and cohesion of the molecules to each other. A scientist wanted to increase the rate of transpiration of a crop species to extend its range into warmer climates. The scientist substituted a nonpolar solution with an atomic mass similar to that of water for hydrating the plants. What do you expect the scientist's data will indicate from this experiment?

#Question id: 396

#Unit 1. Molecules and their Interaction Relevant to Biology

Identical heat lamps are arranged to shine on two identical containers, one containing water and one methanol (wood alcohol), so that each liquid absorbs the same amount of energy minute by minute. The covalent bonds of methanol molecules are nonpolar, so there are no hydrogen bonds among methanol molecules. Which of the following graphs correctly describes what will happen to the temperature of the water and the methanol?

#Question id: 395

#Unit 1. Molecules and their Interaction Relevant to Biology

How would acidification of seawater affect marine organisms? Acidification of seawater would ________.

#Question id: 394

#Unit 1. Molecules and their Interaction Relevant to Biology

What will be the H+ ion concentration in a solution prepared by mixing 50.0 mL of 0.20 M NaCl, 25 mL of 0.10M NaOH and 25.0 mL of 0.30M HCl?