What is the cell membrane is made of

What is the cell membrane made up of?

Proteins and lipids.

Lipids form a double layer that prevents water-soluble substances from passing through cells.

Proteins create channels that control the entry and exit of these substances into cells.

the sugar-phosphate backbone forms the structural framework of nucleic acids, including dna and rna. this backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.

if your own plato the answer is b. the fern transitioned from sporophyte generation to gametophyte generation.