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Principles of Biology

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BIOL-1116_-_Human_Anatomy_Notes.docx-Daniel T. Eisert BIOL-1116 Human Physiology:

Daniel T. Eisert Lesson I: Evolution & Plant Terrestrial Environments BIOL-1106: Principles of Biology QUIZ: July 10, 2017 I. Environmental Challenges for Land Plants A. Desiccation (extreme dryness) i. Cuticle: a wax structure to protect against desiccation to prevent extensive water loss; however, this process limits gas exchange in and out of the plant. ii. Stomata: small mouth-like openings that allows water to diffuse out. B. Transport (development of vascular tissues) i. Tracheids: moves water and minerals in the plant—more of a challenge for larger plants. ii. Xylem: the water transit system for plants. iii. Phloem: transports water and nutrients from the soil. II. Generations in the Haplodiplonic Life Cycle A. Gametophyte (Haploid) i. Goes through mitosis (because haploid) ii. Egg and sperm go through fertilization (fusion of the gametes) B. Sporophyte (Diploid) i. Mitotic cell division ii. Dominance towards diploid which leads to an increase in genetic variation C. Case Study: Angiosperm Life Cycle i. Gametophyte is completely dependent on the sporophyte, for the female gametophytes are enclosed in the ovary of the flower (which is a sporophyte) III. Evolutionary Adaptations (each subsequent clades do have trade-offs, as some simpler species hold territory against encroachment by advanced groups) A. Green Plants – photoautotrophic (gets energy from light to synthesize food); has a common ancestor with all land plants (identification is unknown)–not all photoautotrophs are green plants; red and brown algae are excluded i. Chlorophytes – never could adapt and live on land ii. Streptophyts – include both charaphytes and land plants iii. Charophytes – sister group to land plants (adjacent group that is not part of the group) B. Land Plants – include multicellular haploid and diploid stages and diploid embryos (not found previous plant groups) C. Bryophytes – closest living descendants to the earliest land plants, non-trichophytes (cannot transfer water but has other types of water conducting cells); remain small due to a poor ability to transfer water; lack true roots to absorb water; they are common in moist areas, for they require water to transfer sperm for sexual reproduction; gametophyte – the dominate photosynthetic stage of lifestyle. Distinct clades include the liverwort and moss. D. Tracheophytes – colonized land by developing successful vascular tissue ; they can grow larger due to an increase efficiency in their water transit system; the xylem is good for water conduction, and the phloem conducts sucrose, hormones, and other organic compounds; includes a waxy cuticle and stromata; sporophyte dominant. i. Lycophytes (club mosses) a. Most ancient group of vascular plants (most are not extinct) – the vascular tissue is located in the roots and stems, not leaves. b. No seeds c. Water is required for fertilization. d. Green, leafy sporophytes are the dominant stage. Daniel T. Eisert Principles of Biology Page 1 of 3

BIO | 1106 | Principles of Biology | study guides | Daniel T. Eisert Lesson I: Evo

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 Wind pollination Plant Characteristics  Timing of opening  Patterns  Size  Shape DOUBLE FERTILIZATION  Unique to angiosperms  Fertilization of the egg  diploid zygote – union of the second sperm with a polar nuclide to form triploid endosperm (3n)  Pollen tube : provides a passageway for sperm to reach the embryo sac EMBRYO DEVELOPMENT  Endosperm and embryo  zygote begins mitotic divisions and establishes a 3-D body plan  3-D body plan  Suspensor  links embryo to the nutrient tissues of the seed FRUIT DEVELOPMENT Reserves & Embryogenesis  Food supply – fruit has starches, lipids, and proteins for nutrients – this is critical because photosynthetic tissue is not ready for use immediately after germination  Seed coat  Fruit surrounding the seed (fused to the seed coat)  Dormant stage after embryogenesis DISPERSAL Characteristics  Fruits contain mature ovaries and carpals  ovary and pericarp has three layers with each layer impacting the diversity of food types (outer layer: skin, middle layer: flesh, inner layer: pit around the seed)  Fleshy  Dry  Aggregate  Multiple Dispersal for Colonization  Color change: red/black attract mammals (carried in digestive track of mammals for long distances; however, sometimes the fruit is left at its original location, for it is not swallowed)  Sticky fruits can attach to features and fur  Wind dispersal is good for long distance travel  Water dispersal allows plants to colonize new islands ASEXUAL REPRODUCTION  In some harsh environments, the same genes for subsequent generations is quite advantageous  Apomixis : seed production, the development of an embryo without fertilization  Vegetative reproduction : the new individual is produced from vegetative tissue  Runners/stolons  Rhizomes  Stickers : root sprouts that give rise to new plants  Adventitious plantlets  Somatic embryogenesis (growth of any somatic tissue) SUPPLEMENTAL NOTES Daniel T. Eisert Principles of Biology Page 2 of 2

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