Chapter 20 Bio

Red algae

Closest relative to green plants, does not have chlorophyll b

Integument & Ovule

Megasporangium surrounds a sterile sporophytic structure that forms and integument that protects the megasporangium and its conents Together the megasporangium and integument constitute the ovule

Vascular and Nonvascular land plants

Non Vascular Stomata & Green Sporphyte Liverworts, Mosses, Hornworts Vascular Tracheids Club mosses, horsetails, ferns, cycads, ginko, gnetophytes, conifers, flowering plants

Glaucophytes

- sister to the rest of plants - contain peptidoglycan between inner and outer chloroplast membrane

Terrestrial environment before plant proliferation

-Absence of herbivores on land helped make the first vascular plants successful -Proliferation of plants on land made terrestrial environments more hospitable to animals

similarities in green algae and land plants

-Chlorophyll a, b & starch storage -Retain their eggs in the parental organism -closest relative: stoneworts -Branched apical growth

family to vascular plants

-Closest relatives of living vascular plants belonged to the group rhyniophytes--silurian -Did not have roots, anchored in the soil by horizontal portions of stem called rhizomes -rhizomes bore water absorbing unicellular filaments called rhizoids -Branching was dichotomous Lycophytes -are the club mosses & relatives that are the sister group to the remaining vascular plants. -lycophytes have true roots that branch dichotomously -bear simple leaflike structure called microphylls (single vein) -Sporangia of lycophytes aggregate in conelike structures called strobili which are spore bearing microphylls attached to the end of a stem

Evolution of roots and leaves continued

-Features evolved in lycophytes and monilophytes -Roots probably originated as a branch of a rhizome that penetrated the soil and branched further and was anchored underground -Microphylls of lycophytes were probably the first leaflike structures to evolve among the vascular plants. -Microphylls may have had origins as sterile sporangia

Stoneworts

-Multicellular green algae with branching, apical growth and plasmodesmata between adjacent cells. -The closest living relatives of the land plants they retain the egg in the parent organism.

Significance of primary endosymbiosis for evolution of plants

-Primary endosymbiosis is a shared derived trait of the group called "plantae" -When cyanobacterium was first engulfed by a eukaryote the chloropast that resulted were essential to all life on land-->photosynthesis -There would be no life on land if not for primary endosymbiosis

Seed

-Seed contains tissue from 3 different generation -Seed coat develops from the integument (tissues of the diploid sporophyte parent that surround the megasporangium) -Inside the megasporangium is haploid tissue from the female gametophyte which has nutrients for the embryo -In the center of the seed is the third gen, the embryo of the new diploid sporophyte

archegonium and antheridium

-during the haploid phase of the life cycle the gametophytes produce archegonium (female) and antheridium (male) -these structures produce and protect the gametes until mating

Non vascular plants & limitations

-liverworts, hornworts, mosses -lack efficient vascular system for transporting water and minerals from the soil to distant parts of the plant body -low growing in moist environments -gametophyte dominant

2 types of vascular tissue in plants

-vascular tissues allowed transportation of water and food though the plant body which allowed plants to spread to new terrestrial environments and diversification Xylem conducts water and minerals from the soil to parts of the plant. provides support against gravity from the cell walls stiffening substance called lignin (tracheids and vessel elements) Phloem conducts the products of photosynthesis from sites where they are produced or released to sites where they are used or stored

Steps of alteration of generations

1. Gameteophyte produces haploid gametes by mitosis (n) 2. Gametes fuse to form a zygote (fertilization) 3. Zygote develops into a diploid (2n) mitosis 4. Sporophyte produces haploid spores by meiosis (n) 5. Spores germinate and divide to form haploid gametophyte by mitosis (n)

Alteration of generations land plants

1. life cycle includes both multicellular diploid stage and multicellular haploid stage 2. gametes are produced by mitosis, NOT MEIOSIS. Meiosis produces spores that develop into multicellular haploid organisms

Function of fruits

Aid in seed dispersal Protects the seeds

Embryophytes

Another name for land plants,

5 evolutionary adaptations found in successful land plants

Cuticle- a coating of waxy lipids that retards water loss Stomata-small closable openings in leaves and stems that are used to regulate gas exchange and water loss Gametangia- multicellular organs that enclose plant gametes and prevent them from drying out Embryos- young plants contained within a protective structure Certain pigments- afford protection against mutagenic ultraviolet radiation that bathes the environment

4 groups of gymnosperms

Cycads Palm like, earliest diverging clade, tissues highly toxic to humans Ginkgos Common during mesozoic, have distinct sex chromosomes like humans Gnetophytes certain characteristics analogous to angiosperms, (Welwitschia) desert plant with two straplike leaves Conifers Most abundant of gymnosperms. Cone bearing plants

Angiosperm

Enclosed seed Derived from another distinctive trait of flowering plants that is related to the formation of fruits:ovules and seeds are enclosed in a modified leaf called carpel Shared derived traits of angiosperms Flower: Sexual structure of the angiosperm Fruit: After fertilization the ovary of a flower & seed develops into a fruit that protects the seeds and can promote seed dispersal

Monilophytes & Seed plants clade

Euphyllophytes (true leaves) Important synapomorphy of this clade is overtopping: growth pattern in which one branch differentiates from and grows beyond the others Overtopping would give plants advantage in the competition for light. Overtopping of euphyllophytes allowed larger more complex leaves to evolve called megaphylls. Horse tails: Reduced true leaves that form circles around the stem. Have rough silica deposits useful for cleaning. Large sporophyte and small gametophyte independent of eachother Ferns Require water for transport of male gametes to the female gametes so they inhabit shaded moist swamps Sporangia of ferns typically are borne on a stalk in clusters called sori. Sori are found on the undersurfaces of the leaves

tracheids

Fluid-conducting cells that all vascular plants have

Spores, sporangia, gametangia, gametes

Gametes are produced by mitosis meiosis produces spores that develop into multicellular haploid organisms. Sporophytes contain reproductive organs called sporangia which is what undergoes meiosis to produce spores. Those spores develop into into a haploid plant by mitosis called the gametophyte which produces haploid gametes using gametangia by mitosis, and those two fertilize into a zygote and the cycle continues

Plantae

Group of organisms that are eukaryotic, have cell walls, and can photosynthesize

Two major groups of seed plants

Gymnosperms "Naked-seeded" seeds are not protected by ovary or fruit tissue Cycads Ginkos Gnetophytes Conifers (most abundant) Redwoods are gymnosperms! With the exception of gnetophytes gymnosperms have only tracheids as water conducting support cells in the xylem, and most lack the vessel elements and fibers specialized for water conduction and support. Angiosperms

Aquatic plants vs Land plants

Land 1.Protected embryo 2.Vascular Tissue 3.Seeds 4.Alteration of generations

5 Major clades of plants

Landplants: Protected embryo Vascular: Tracheids (vascular cells), rooting structures, independent sporophyte Euphyllophytes Megaphylls Gymnosperms Seeds Angiosperms Flowers

Nonvascualr plants & Characteristics

Liverworts (hepatophyta) -leaflife gametophytes that lie close to the ground -can produce sexually or asexually through division of gametophyte -sporophyte (small) remains attached to gametophyte mosses (bryophyta) -found in damp cool ground where they form thick mats -have stomata important for water retention and gas exchange -some moss gametophytes so large they can't transport enough water through their bodies solely by diffusion -contain "hydroid" similar to tracheid, which dies and leaves tiny channel for water Hornworts -sporophytes look like horns -cells contain single large, platelike chloroplast as opposed to the other 2 that have numerous lens shaped chloroplast -sporophytes capable of growth without a set limit -no stalk and persistently green like vascular plants -Symbiotic relationship with cyanobacteria that helps with access to nitrogen

Cones

Male and female cones contain the reproductive structures of conifers Female=megastrobilus, woody cone of pine trees that protect the seeds Male= microstrobilus, smaller pollen bearing cone, herbaceous rather than woody

Heterospory

Megaspore develops into a specifically female gametophyte called megagametophyte that produces only eggs. Microspore is smaller and develops into a male gametophyte called microgametophyte that produces only sperm The sporophyte produces megasporangia in small numbers and microsporangia in large numbers. Heteropspory increases opportunites for long distance cross fertilization and increases chances of survival for the developing embryo.

Micropyle

Opening in the integument of a seed plant ovule through which pollen grows to reach the female gametophyte within

Innovations of seed plants

Pollen Increases reproductive opportunities Seeds provide a secure and lasting structure that protects the dormant stage of the embryo for up to centuries until conditions are right for germination

Pollination and fertilization

Pollination The arrival of a pollen grain at an appropriate landing point close to a female gametophyte on a sporophyte of the same species Fertilization Once pollen grain reaches pollination it produces a slender pollen tube that makes it way toward the megagametophyte, then sperm is released from the tube and fertilization occurs.

Homospory

Producing a single type of spore that gives rise to a single type of gametophyte bearing both male and female productive organs.

Secondary growth

Proliferation of xylem led to thick woody stems and allowed seed plants to grow to great heights. The product of secondary growth is secondary xylem or wood.

Characterisitcs used to distinguish land plants from green algae

Protected embryo True roots green sporophyte vascular cells stomata veined leaves seeds flowers ^^All exclusive to land plants

Structure of flower

Stamen The structures bearing microsporangia (anthers & filaments) Filament Each stamen is composed of a filament bearing an anther that contains pollen-carpels. Ovary Swollen base of the carpel containing one or more ovules each containing megasporangium Style The stalk at the top of the carpel Stigma Terminal surface that receives pollen grain Pistil Two or more fused carpels or a single is called a pistil Petals (collectively corolla) Inner specialized non spore bearing leaves. Sepals (collectively calyx) Outer specialized non spore bearing leaves Carpel stigma, style, & ovary

Pollen grain structure, function, source

Within the spore wall of a microspore it divides mitotically one or a few times to form a multicellular male gametophyte called a pollen grain. They are released from the microsporangium to be distributed by wind or by an animal pollinator -Spore wall that surrounds the pollen grain contains a substance called sporopollenin the most chemically resistant biological compound known. -Sporopellenin protects the pollen grain against dehydration and chemical damage

tracheophytes (vascular plants)

plants with vascular tissue

phycoerythrin

red pigment in red algae

Lignin

substance in vascular plants that makes cell walls rigid. Tracheids & Vessel elements make up the lignin of the xylem. Lignin is essential for growing upwards and compete for sunlight on land

embryo

the diploid cell formed by mitosis from the haploid gametes