Exam 2 Flashcards
How are the taxa within Kingdom Plantae related to each other?
Bryophytes are seedless, non-vascular plants. Ferns are seedless vascular plants, having xylem and phloem. Gymnosperms are seed bearing, flowerless vascular plants. Angiosperms are seed bearing, flowering vascular plants.
What organism is suspected to be the common ancestor of all plants
Green algae
Advantages and disadvantages plants experienced transitioning from aquatic to terrestrial habitats
Advantages- escape from water-based predation, greater access to sunlight and carbon, CO2 is more readily available,
disadvantages- need water to prevent desiccation and to provide structure through buoyancy, sperm and egg can easily find each other in water, water filters out destructive UVB radiation
Compare and contrast 4 main plant clades
Mosses (bryophytes) are the most “primitive” of plant species, needing to exist very near or in water due to lack of a vascular system. They produce spores and rely heavily on water for reproduction.
Ferns (seedless vascular plants) are the “next step up”, having vascular tissue and the first real plant organs (roots, stems and leaves), allowing them to grow more vertically. They still reproduce via spores but are less dependent on water. Reproduce via alternation of generations. Gametophytes are multicellular and free living.
Gymnosperms produce seeds and reproduce via sporophyte dominant life cycle. Reproduce via pollination through wind. Unlike angiosperms, they do not have flowers or fruits.
Angiosperms have flower and fruits, and are sporophyte dominant, though multicellular gametophytes still exist in the plant.
Characteristics common to each plant clade
Bryophytes- dominated by a multicellular gametophyte stage; no vascular tissue or lignin; no true roots or leaves.
Ferns (seedless vascular plants)- lifecycle dominated by a diploid sporophyte with a free living multicellular gametophyte. vascular tissues but no lignin
Gymnosperms- Naked seeds (no flower or fruit), needle-like leaves, typically develop in colder areas, perennial, have lignin, no ovary/style/stigma, cones contain reproductive structures, seed contains endosperm, xylem has no vessels and phloem has no companion cells or sieve tubes.
Angiosperms- flowers are the reproductive organ of the plant, xylem has vessels, phloem has companion cells and sieve tubes, ovules are enclosed in the ovary at the base of the flower, produces 2 kinds of spores,
Describe the development and adaptation of seeds
Seeds developed as a way to protect the diploid embryo before fertilization. Hard outer casings prevent desiccation, while storage tissue sustain growth.
Describe the evolution and development of vascular tissue (Xylem and phloem)
Xylem are hollow tubes that allow for the two way transportation of water. Phloem allows for the transport of sugars from photosynthesis down to the root. They allow for the plants to grow taller and access more sunlight.
Describe the evolution and development of the fruit and flowers
Pollinating via active pollinators instead of the wind is much less random, and thus more successful. Double fertilization for both the zygote and the endosperm increases the chance of fertilization success.
Describe main characteristics of bryophytes
No true roots or leaves, no vascular tissue, reliant on water for reproduction, gametophyte dominant life cycle.
Describe the main characteristics of seedless vascular plants
Roots, leaves and stems; vascular tissue; sporophyte dominated life cycle with free living gametophyte.
Describe the main characteristics of gymnosperms
Needle-like leaves, lignin, naked seeds, double fertilized seed with endosperm, perennial
Describe the main characteristics of angiosperms
Flowers and fruits, eggs contained in ovule inside ovary at the base of the flower, produces 2 kinds of spores.
Describe the life cycle of bryophytes
Alternation of generations; germinated spores become protonema, which grows into a diploid gametophyte, male and female sex organs (antheridia and archegonia respectively) are produced on the gametophyte. Haploid sperm released from antheridia, making a diploid fertilized cell when combined with a haploid egg, which develops into a diploid sporophyte.
Describe the life cycle of seedless vascular plants
Alternation of generations where the diploid sporophyte alternates with the haploid gametophyte stage. When spores fall they develop into a tiny gametophyte with antheridia and archegonia. When egg and sperm combine, they become a diploid plant.
Describe the life cycle of gymnosperms
Sporophyte dominant:
Female cones contain haploid ovules which undergo meiosis, then a remaining haploid megaspore undergoes mitosis to produce a female gametophyte. Male cones produce microspores which undergo mitosis to become pollen grains. Through wind pollination, the male pollen fertilizes the female gametophyte, leading to a diploid zygote and eventually embryo.
Describe the life cycle of angiosperms
sporophyte dominant with male and female gametophytes.
Male gametophyte- undergoes meiosis then mitosis to form pollen, which contains 2 sperm and a 3rd cell that will become pollen tube
Female gametophyte- megasporangium divides via meiosis to form 3 antipodal cells, 2 polar nuclei, 2 synergid or helper cells, and 1 egg.
Fertilization-when pollen reaches the stigma a pollen tube extends down the style. 1 sperm cell fertilizes the egg to become zygote, 1 sperm cell fuses with 2n polar nuclei to become endosperm.
What general adaptations have plants evolved to defend themselves against other organisms and or harsh environmental conditions?
Thorns, poisonous tissue, hard seed shells
Describe the main adaptations of carnivorous plants, including trapping mechanisms and digestion/nutrient assimilation.
Identify and describe the major organs, tissues and specified cell types of a typical vascular plant body.
Relate form to function of plant organ, tissues, and cells.
Describe general adaptations that plants have evolved to modify major plant organs (stem, root, leaf, flower) to meet various environmental constraints.
