L16: evolution of plants II
Explain the adaptations that led to the success of angiosperms, including the significance of their reproductive structures
"Enclosed seeds" the importance of angiosperms is that they produce seeds and pollen. Their significance in reproduction is that angiosperms produce flowers which have the most reproductive success in all plants. The success of angiosperms on land is attributed to their flowers, which attract animals to their plants, and to their fruits, which disperse seeds
pollen
A fine dust that contains the sperm of seed-producing plants
double fertilization
A mechanism of fertilization in angiosperms, in which two sperm cells unite with two cells in the embryo sac to form the zygote and endosperm.
ovule
A structure that develops within the ovary of a seed plant and contains the female gametophyte.
endosperm
In angiosperms, a nutrient-rich tissue formed by the union of a sperm with two polar nuclei during double fertilization. Provides nourishment to the developing embryo in angiosperm seeds.
homospory
In seedless vascular plants, the production of just one type of spore.
Describe dispersal mechanisms of nonvascular plants, seedless vascular plants, gymnosperms
Nonvascular: Produce flagellated sperm that swims through WATER to fertilize eggs Seedless vascular: Have sporangia that occur in clusters known as sori, Within the sporangia, meiosis occurs, creating haploid spores, These are dispersed by WIND Gymnosperms: Two types ofc ones: ovule cones and pollen cones, Pollen grains dispersed into WIND Angiosperms: Fruits are used so that animals can spread the seeds
conifer
evergreen, cone-bearing tree
secondary metabolite
organic compounds that are not directly involved in the normal growth, development, or reproduction of an organism
Compare and contrast the relative importance of the sporophyte vs gametophyte generation between nonvascular plants (bryophytes), seedless vascular plants and seed plants
-nonvascular (game) dominant gametophyte generation sporophyte generation small and short-lived -seedless vascular (both) can either have dominant gametophyte generation or dominant sporophyte generation -seed plants (spore) have dominant sporophyte generation
Illustrate the phylogenetic relationships among the major groups of plants, including the points on the tree where major adaptations appeared, such as ovaries, pollen, vessels, seeds, flowers, leaves, and roots, etc.
Broke off from nonvasc bryophytes o Stems, leaves and roots o Dominant sporophyte generationo LigninBroke off from seedless vascular ferns o Ovules, pollen, seeds, wood Broke off from angiosperms o Flowers, fruits, endosperm in seeds
Describe the influence of humans on angiosperm diversification
Selective breeding: Virtually all crops have been artificial selected for traits desirable to humans
heterospory
produces both microspores (male gametophytes) & megaspores (female gametophytes)
Describe the process of coevolution between land plants and animals (e.g. angiosperms and pollinators, angiosperms and fruit eaters, seed plants and herbivores)
-Process by which two or more species of organisms influence each other's evolutionary pathway -Explains the diverse forms of most flowers and many fruits, and how plants accomplish effective pollen and seed dispersal -Floral tubes and coevolved pollinators -Diversification: pollinators foster genetic variability in plants via fidelity, as pollinators visit certain flower types preferentially, If pollinator becomes extinct, plant may also face extinction -Influenced both plant fruit chracteristics and animal seed -dispersal agent - Secondary metabolites: synthesis of molecules that are not essential for cell structure and growthCan be used for defense or competition with neighboring plants
explain how seeds and pollen are adaptations that seed plants have for arid environments
-Seeds: Embryo and food supply, plus protection.allow plants to reproduce in diverse habitats -Pollen: Allows seed plants to disperse male gametophytes. -Wood: provides a stable structure and protection.
