Which of these particles is able to pass freely through a cell membrane?

The correct answer is d) oxygen molecule. Cell membrane or a phosphate bilipid layer is semi-permeable in nature i.e. it allows selective molecules to pass through it. Small and uncharged molecules can easily pass though it however, it prevents the movement of large and charged molecules.

Explanation:

A

Explanation:

I'm mostly sure that the answer would be A, because I'm mostly sure that it is a hydrophilic molecule

they may bind directly to special “promoter” regions of dna, which lie upstream of the coding region in a gene, or directly to the rna polymerase molecule.