BISC 1112 Final: Plant Competition

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Biological Sciences
BISC 1112

Plant Competition Major clades • Bryophytes (moss) o Gametophyte generation is dominant in the life cycle o Surface of gametophyte is covered in waxy coating to retain moisture o In few bryophytes, the outer surfaces are perforated with pores and the capsule may have true stomates surrounded by guard cells for CO a2d O ex2hange o Rhizoids- anchor the moss plant, but are not true roots and do not absorb water from the soil. o Absorb water by diffusion through their surfaces, but have no true vascular system  no tall bryophytes o Bryophyte Reproduction- when haploid meets water, they grow into either a male gametophyte (antheridium) or a female gametophyte (archegonia) which produced sperm and eggs ▪ Once fertilization occurs, sporophyte grows directly on top of the gametophyte archegonia and remains attached to and thus, absolutely dependent upon the gametophyte during its entire life. ▪ specialized cells at the top of the diploid (2n) sporophyte undergo meiosis and produce single-celled spores (n) ▪ 2n  n  2n • Algae (unicellular, multicellular, and colonial) o No protective waterproof covering o Egg and sperm must swim to find each other o Water alone buoys up their photosynthetic parts to get sunlight • Ferns o Surface is waxy coating that keeps moisture in and stops evaporation, yet it is perforated with stomates to allow the exchange of gases. o Ferns have true roots to absorb water and minerals o Xylem and phloem- vessels are found throughout the entire plant in order to transport water, minerals, sugar, and other molecules ▪ These rigid walls of these tissues provide skeletal support which allows ferns to grow taller than mosses o Fern Reproduction- most fern sporophytes produce only on type of spore that then grows into one type of gametophyte (n) ▪ Each multicellular gametophyte produces archegonia (female) and antheridia (male), which eventually make and sperm cells. ▪ Sperm cells can only reach the egg by swimming; thus, fertilization is still dependent upon the presence of a good deal of moisture in the archegonia ▪ After fertilization, a new diploid (2n) fern sporophyte grows out of the archegonia, but it is only briefly dependent upon the gametophyte ▪ Gametophyte- Insects ▪ Sporophyte- wind ▪ Diploid sporophyte is the dominant generation, which is essential what you see when you are looking at a fern • Gymnosperms (conifers ad relatives) o New growth in the vascular cambium increases the girth of the stem, and creates a woody tissue. Each year the vascular cambium produces new to its inside and phloem to its outside. ▪ The secondary xylem accumulates, but the secondary phloem is eventually lost, often being sloughed off with the bard o Wood is the accumulation of dead tissues with their
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