Question

question 5
which molecule is least likely to cross a cellular membrane by simple diffusion?
water
oxygen
potassium ion
carbon dioxide
question 6
what type of molecule can rapidly cross a plasma membrane?
small polar molecules
large, polar molecules
small, hydrophobic molecules
large, hydrophobic molecules
question 7
sodium - potassium pumps help to maintain a separation of charges across the plasma membrane, which is called the ______________.
macrophage
electron gradient
proton gradient
membrane potential

Explanation:

• Question 5: Simple diffusion across a cellular membrane is more difficult for charged particles. Potassium ion is a charged species, while water, oxygen, and carbon - dioxide are uncharged or non - polar molecules that can diffuse more easily.
• Question 6: Small, hydrophobic molecules can rapidly cross a plasma membrane because the plasma membrane has a hydrophobic interior (lipid bilayer). Hydrophobic molecules can dissolve in this lipid environment and pass through quickly.
• Question 7: Sodium - potassium pumps maintain a separation of charges across the plasma membrane, which is called the membrane potential. A macrophage is a type of cell, and electron and proton gradients are related to other cellular processes like respiration and photosynthesis.

Answer:

• Question 5: Potassium ion
• Question 6: Small, hydrophobic molecules
• Question 7: Membrane potential