It seems that you have missed the necessary options for us to answer this question so I had to look for it. Anyway, here is the answer. Varicose veins seen in the superficial veins of the legs are unsightly and often treated by surgically removing them. however, even without these veins being present, the return of all blood toward the heart from the legs is not diminished primarily because <span>blood can still return via the deep veins. Hope this helps.</span>
<span>A mature sporophyte produces spores by meiosis, a process which reduces the number of chromosomes to half, from 2n to n. Because meiosis is a key step in the alternation of generations, it is likely that meiosis has a fundamental adaptive function. The nature of this function is still unresolved (see Meiosis), but the two main ideas are that meiosis is adaptive because it facilitates repair of DNA damages and/or that it generates genetic variation.
The haploid spores germinate and grow into a haploid gametophyte. At maturity, the gametophyte produces gametes by mitosis, which does not alter the number of chromosomes. Two gametes (originating from different organisms of the same species or from the same organism) fuse to produce a zygote, which develops into a diploid sporophyte.</span>
