membrane transport, SA:V, and aquaporins Flashcards
(12 cards)
What types of substances require channel proteins to cross a membrane?
Charged ions like Na⁺, K⁺, and Cl⁻.
Why can alcohol pass through the cell membrane easily?
Because it dissolves in the phospholipid bilayer.
What risk does high concentration alcohol pose to cells?
It releases heat that can damage the membrane.
Why can’t water easily cross the membrane on its own?
The hydrophobic tails of the membrane block it.
What are aquaporins?
Channel proteins that help water cross the membrane efficiently.
How does the size of a molecule affect its ability to cross a membrane?
Smaller molecules pass through more easily; large ones require active transport methods.
What is the SA:V ratio?
The surface area of a cell compared to its volume.
Why do small cells have a better SA:V ratio?
Because more surface area per volume allows faster and more efficient exchange of substances.
What are the advantages of having a high SA:V ratio?
Quicker absorption of nutrients and faster removal of waste.
What happens when a cell’s SA:V ratio is too low?
Exchange becomes inefficient; waste builds up, and nutrients may not reach the center in time.
What is the largest organ in the body?
The skin.
Name three functions of the skin.
Protection, temperature regulation, and sensory reception.
