Which of the following modifications to histone “tails” (the N-termini of histones) can lead to DENSER packing of DNA?

In flourescence microscopy, the reason that excitation light and emission light are different colors is because: 

Which statement is FALSE about the ubiquitin pathway?:

What substance is LEAST likely to diffuse through a lipid bilayer on its own (without the help of a membrane transport protein)?

Phospholipids that have small polar headgroups and 2 long fatty acid tails are more likely to form:

The internal temperature of hibernating mammals, such as bears, drops when they hibernate. How do they maintain the fluidity of their cell membranes to compensate for this drop?

What is a TRUE statement about passive transport

Trans unsaturated fatty acid tails pack:

In plant cells, H+ pumps maintain a low concentration of H+ inside the cell. As long as a low H+ concentration is maintained inside the cell, H+ -driven symporters on plant cell membranes can use the electrochemical gradient of H+ to:

The “hydrophobic effect” is the driving force of the spontaneous assembly of the lipid bilayer of cell membranes in water. What does that mean?