Cyanobacteria likely existed on land ___ _______ years ago.
Around ___ _______ _____ ago, small plants, fungi, and animals emerged on land
500 billion years
Since colonizing land, how many plant species have diversified?
roughly 290, 000
Land plants are defined by ...
having terrestrial ancestors, even though some now might be aquatic
they do not include photosynthetic protists (algae)
Plants supply ______ and are the ultimate source of most food eaten by land animals.
Land plants evolved from _____ _____.
green algae (charophyte)
4 traits land plants share with algae.
1) Alternation of generations and Multicellular, Dependent Embryos 2) Walled Spores produced in Sporangia 3) Multicellular Gametangia
Alteration of generations and multicellular, dependent embryos
life cycles of land plants occur in two generations of multicellular organisms : gametophytes and sporophytes.
each generation gives rise to the other
this occurs in most algae, but not charophytes
distinguished by the fact that the life cycle includes multi-cellular haploid organisms and multi-cellular diploid organisms
5 generalized steps of alternation of generations
1) the gametophyte produces haploid gametes by mitosis. 2) Two gametes unite (fertilization) and form a diploid zygote. 3) the zygote develops into a multicellular diploid sporophyte. 4) the sporophyte produces haploid spores by meiosis. 5) the spores develop into multicellular haploid gametophytes.
Walled Spores Produced in Sporangia
sporophytes have multiple organs called sporangia that produce spores.
prevents exposed zygotes from drying out
alos found in plant spore walls
charophyte algae lack multicellular sporangia and their flagellated, water-dispersed spores lack sporopollenin.
the production of gametes within multicellular organs called gametangia
female gametangia called archegonia male gametangia called antheridia
localized regions of cell division at the tips of roots and shoots.
cells produced by Apical Meristems differentiate into the outer epidermis, which protects the body, and various types of internal tissue
4 key traits land plants SHARE with charophytes
1) rings of cellulose-synthesizing complexes 2) peroxisome enzymes 3) structure of flagellated sperm 4) formation of phragmoplast
kingdom of plants
dependency of the embryo on the plant
How are nutrients transferred from plants to embryo?
placental transfer cells
produce eggs and are the site of fertilization
produce and release sperm
additional derived trait of plants waxy covering of the epidermis aids in waterproofing, helping prevent excessive water loss while aiding in protection from microbial plants.
additional derived trait of plants symbiotic associations between fungi and land plants that may have helped plants without true roots to obtain nutrients
create SA, obtain nutrients
additional derived trait of plants deters herbivores and parasites
Fossil evidence indictates that plants were on land at least ___ _______ _____ ago.
475 million years
Fossilized spores and tissues have been extracted from ___ _______ ____-old rocks.
475 million year
land plants are grouped based on the
presence or absence of vascular tissue
nonvascular plants are called
clades of seedless vascular plants
lycophytes (club mosses and their relatives) pterophytes (ferns and their relatives)
seeless vascular plants are paraphyletic - of the same biological organization, or grade
embryo and nutrients surrounded by a protective coat
gymnosperms and angiosperms
the "naked seed" plants, including the conifers
Mosses and other nonvascular plants have lifecycles dominated by .....