I dont remember much of biology but i do remember my teacher saying something about phosphate backbone, i know its not much help. sorry!!
B. Scarcity of drinking water
The haploid male (sperm) and female (egg<span>) sex </span>cells<span>; in </span>plants<span>, formed by mitosis of haploid </span>cells<span> in the gametophyte. ... The multicellular diploid portion of the </span>plant life cycle<span> resulting from the growth, mitosis, and </span>cell<span> division of a zygote. </span>Produces<span>sporangium that store haploid spores. Google*</span>