Question

proteins do not pass through plasma membranes because
they bind to the phospholipids.
the membrane is made of protein.
they are very large molecules.
they contain nitrogen.
they cause emulsification.

question 4
following a meal, glucose must move from the gut lumen, where there is a high glucose concentration, through membrane proteins and into intestinal cells, where there is a relatively low glucose level. this movement is called
passive transport
active transport
endocytosis
exocytosis
facilitated diffusion.

Explanation:

For the first question:

• Proteins are large molecules. Plasma membranes have a selective permeability. Small non - polar molecules can pass through easily (by simple diffusion), but large molecules like proteins cannot pass through the phospholipid bilayer directly. Binding to phospholipids is not the main reason for not passing through. The membrane has proteins but that's not why proteins can't pass. Nitrogen content is not relevant to membrane passage. Emulsification is not related here.

For the second question:

• Facilitated diffusion is the movement of molecules (in this case, glucose) from an area of higher concentration to an area of lower concentration (from gut lumen to intestinal cells) with the help of membrane proteins (carrier or channel proteins). Passive transport is a general term. Active transport is against the concentration gradient. Endocytosis and exocytosis are for bulk transport of substances (not just a single molecule like glucose in this context).

Answer:

First question: they are very large molecules.
Second question: facilitated diffusion.