Biology homework help? Explain why conifers are described as being the first plants, fully adapted to dry land

Question

I can't find it anywhere in my textbook section that I'm working on....and I can't find it on wikipedia either! Can anyone help?

Answer 1

I'm not sure why they would describe conifers as being the first plants fully adapted to dry land because there were millions of years of plant life on dry land prior to conifers. See http://www.geocities.com/mocraig2000/plants.htm

Another resource that might help you is
http://universe-review.ca/R10-23-plants.htm
Make sure to scroll down a bit to the Permian Period which better addresses your question.

Answer 2

Bryophytes survive drought but are not adapted to the arid periods living on land away from water entails. All pants have a cell wall but that doesn't block evaporation. To prevent desiccation a waxy cuticle to act as a waterproofing developed. Along with this arose pores as openings to exchange gases across. Bryophytes achieved all of this to survive on land. So they colonized all survivable regions near water.
The third thing they need is support to compete for space by growing taller. Special rigid cells are needed in multicellular plants to hold them up against gravity's pull allowing plants to grow large vertically. They get just as large as a prostrate plant on a small area. Ferns developed this. Vascular movement of nutrients followed the vertical growth the woody structure supported. Bryophytes are nonwoody, nonvascular plants so remain short and spreading. Ferns were the first vascular plants but they still needed moisture to ensure fertilization. They are still competing with bryophytes for the limited space near water to reproduce.

Wind dispersion of reproductive cells allowed plants to colonize land away from constant water supplies. If water is going to passively carry gametes to each other and protect them from desiccation plants were limited to densely inhabited space near water sources. Bryophytes & ferns are dependent on moist environments for reproduction but the first seed plants developed an alternate delivery system allowing independence from water assisted reproduction. Conifers produce pollen that can survive by carrying water and nutrients along. Wind can now carry these male gametophytes to female gametophytes under the scales of a cone. Fertilization produced a diploid seed. The seed is protected and can survive dry conditions for a period of time before growing.