Dna is sometimes described as a ladder-shaped molecule. what would be the best description of the composition of the rail portion that runs up each side of the ladder?

The sugars in the backbone

The backbone of DNA is based on a repeated pattern of a sugar group and a phosphate group. The full name of DNA, deoxyribonucleic acid, gives you the name of the sugar present - deoxyribose.

Deoxyribose is a modified form of another sugar called ribose. I'm going to give you the structure of that first, because you will need it later anyway. Ribose is the sugar in the backbone of RNA, ribonucleic acid.

well this my answer.

releases oxygen is a light-independent reaction and so is (fixes carbon dioxide. light-dependent reaction takes place in the stroma and lights dependent reaction take place in the grana, light-dependent reactions produce atp. and last but not least, light dependent reactions produces glucose.

hope it : )