Question

Question 2

Which of the following best describes how both symport and antiport transporters move two different types of molecules?

They move two molecule types down both of their electrochemical gradients.

They move two molecule types up both of their electrochemical gradients.

They move one molecule type up and one down their electrochemical gradients.

They move two molecule types into the cytosol.

They move two molecule types out of the cell.

They use ATP to power active transport.

Question 3

Which of the following is TRUE regarding the resting membrane potential of a cell?

The resting membrane potential for most animal cells is 0 mV, because the positive and negative ions are in balance.

The resting membrane potential for most animal cells is positive, because Na⁺ ions are so plentiful inside cells.

The resting membrane potential for most animal cells is negative, because more positively charged molecules are pumped out of the cell than are pumped in.  

At the resting membrane potential, the electrochemical gradients of all ions are in equilibrium and therefor no ions enter or exit the cell.

Question 4

Place the following types of molecules in order of least likely to most likely to diffuse across a cell membrane with no proteins for transport.

1) small uncharged polar molecules

2) small nonpolar molecules

3) charged ions

4) large uncharged polar molecules

Question 5

Which of the following statements about membrane transport proteins is TRUE?

Transporters only move large molecules while channels only move small molecules.

Transporters are always active while channels are always passive.

The specificity of transporters is due to size and charge, while the specificity of channels is due to the fit of a molecule to a binding site.

The specificity of transporters is due to the fit of a molecule to a binding site, while the specificity of channels is due to size and charge.

Answer 1

Ans-2- transport by cotransporter is always coupled means neither molecules can move alone. The energy generated by transport of 1 molecules along the concentration gradient is used to transport the other molecule against the concentration gradient. Hence one molecule is moved up and one down their electrochemical gradient.

Hence option C is right.

Ans-3- value of resting membrane potential is -70 mV.this is because the interior of cells have more negative charge than positive charge and exterior of cells have more positive charge molecules than negatively charge molecules.

Hence option C is right.

Ans-4- cell membrane is hydrophobic allowing the small hydrophobic molecules pass easily while restricting the movement of charged or polar molecules. Order of decreasing digfusity is-

Small non polar molecules > small uncharge polar molecules >large uncharted polar molecules > charged ion

Ans-5- specificity of channels is because of small pore size of channel restrict the entry of The ions of inappropriate size and charge while transporter specificity is similar to enzyme. A molecules can only be transported if it's binding is fit to the active site of transporter.

Hence last option  is right.