(closest related green algae(GA) to land plants(LP):shares features of both)

Zygote=one diploid cell(GA)

Haploid Stage is Multicellular(LP,GA)

Complex Branching(LP)

Complex Sex Organs(LP)

1. Alternation of Generations

2.Walled Spores produced in Sporangia

3.Multicellular gametangia

4. Apical Meristems

Alternating life cycles between 1N and 2N

Gametophyte: Haploid(1N), Produces Gametes via mitosis

Sporophyte: Diploid(2N) produces spores via Meiosis

-Diploid Embryo tetained within tissue of female gametophyte

-Nutrients transferred to embryo via placental transfer cells

-Land plants are called (Embryophytes): Embryo is dependent on parent plant

-Sporophye produces spores in organs called Sporangia

-Sporocytes undergo meiosis to generate haploid spores

-Spore wall contain sporopollenin: which is resistant to harsh enviorments

Multicellular Gametangia

Where are Games produced?

Games produced in organs called Gametangia

-Male Gametangia called Antheridia which produces sperm

-Female Gametangia called Archegonia which produces eggs and is the site of feritlization.

-Located region of cell division that allows the plant to sustain growth throughout its life.

-Cells differentiate into various tissues

-unfiltered sunlight

-Gases diffuse rapidly

-Fewer predators/competitors(initially)

-Desiccation

-support

-dispersal

-access nutrients (other than gases)

-non vascular plants

-gametophye dominent

-offspring stays attacehd to mother plant for nourishment

include:

-mosses(phylum Bryophata(stomata on sporophyte)

-hornworts(phylum Anthocerophyta(stomata on sporophyte)

-liverworts(phylum Hepatophyta)

-no conuducting(vascular) tissues

-growth height limited

-max 2M(wet conditions)

-Earliest were small plants with independent, branching sporophytes.

-Vascular tissue for internal transport(xylem and phloem)

-cell walls reinforced with lignin

-Dominant sprophyte life cycles

-roots and leaves

Phylum Lycophyta(clube mosses ect)

Phylum Pterophyta(ferns)

-Dominant during Devonian and Carboniferous periods.

*first trees that gave rise to coals

-Lycophytes have microphylls

-all other vascular plants have Megaphylls

Sori: are on ferns, clusters of Sporangia on undersides of sporophylls.

Strobili:Cone like structures formed from groups of sporophylls, located on lycophytes and gymnosperms

CH(30)

What are traits common to all seed plants?

4main (-heterosporous, ovule, pollen, reduced gametophytes)

-parental sporophyte does note release spores but keeps them in sporangia. The gametophyte develops in the confines of the spore

-Female gametophytes are retained on parent sporophye

-layers of sporophtye tissue called "integument" envelop megasporangium

-vascular tissues

-Mega sporangium-->Megaspore-->Female Gametophyte-->eggs

-Microsporangium-->Microspore-->Male gametophyte-->sperm

-Ovule is integument, megasporangium, and megaspore

-Gymnosperm megaspores have 1 integument

-Angiosperm megaspores have 2 integument

The gametophytes of seed plants develop within the walls of spores that are retained within tissues of the parent sporophyte

They may remain dormant for days to years, until conditions are favorable for germination

They may be transported long distances by wind or animals

Microspores develop into

, which contain the male gametophytes

If a pollen grain germinates, it gives rise to a pollen tube that discharges two sperm into the female gametophyte within the ovule

Pollen eliminates the need for a film of water and can be dispersed great distances by air or animals

•

The gymnosperms have "naked" seeds not enclosed by ovaries and consist of four phyla:

-Cycadophyta (cycads)

-Gingkophyta (one living species: Ginkgo biloba)

-Gnetophyta (three genera: Gnetum, Ephedra, Welwitschia)

–

Coniferophyta (conifers, such as pine, fir, and redwood)

-Gymnosperms appear early in the fossil record(305 ma)

-dominated the Mesozoic terrestrial ecosystems

-Gymnosperms were better suited than nonvascular plants to drier conditions

-today cone bearing conifers dominate in the northern latitudes

Phylum Cycadophyta ?

-Individuals have large cones and palmlike leaves.

- These thrived during the Mesozoic, but relatively few species exist today.

Phylum Ginkgophyta ?

-This phylum consists of a single living species,

Ginkgo biloba

-It has a high tolerance to air pollution and is a popular ornamental tree

Phylum Gnetophyta

consist of three phyla(Gnetum, Ephedra, Welwitschia)

-Live in tropical and desert enviorments)

Phylum Coniferophyta

-This phylum is by far the largest of the gymnosperm phyla.

Three key features of the gymnosperm life cycle are:?

-Dominance of the sporophyte generation

-Development of seeds from fertilized ovules

　-

The transfer of sperm to ovules by pollen

-Takes three years to make a pine seed

-The pine tree is the sporophyte and produces sporangia in male and female cones

-Small cones produce microspores called pollen grains, each of which contains a male gametophyte

-The familiar larger cones contain ovules, which produce megaspores that develop into female gametophytes

-It takes nearly three years from cone production to mature seed

All angiosperms are classified in a single phylum, Anthophyta

-Phylum Anthophyata

-Stamen and Carpel(FLower)

-Many insects and animals transfer pollen

Sepals: which enclose the flower 

Petals: which are brightly colored and attract pollinators

Stamens: which produce pollen on their  anthers (consist of anther and filament)

Carpels: which produce ovules

•

A carpel consists of an ovary at the base and a style leading up to a stigma

, where pollen is

-typically consists of a mature ovary but can also include other flower parts

-Fruits protect seeds and aid in their dispersal                                  

-Various fruit adaptations help disperse seeds

-Seeds can be carried by wind, water, or animals to new locations \

-Mature fruits can be either fleshy or dry

The Angiosperm Life Cycle ?

 1. A pollen grain that has landed on a stigma germinates and the pollen tube of the male gametophyte grows down to the ovary

2.The ovule is entered by a pore called the micropyle

3.Double fertilization occurs when the pollen tube discharges two sperm into the female gametophyte within an ovule

The Angiosperm Life Cycle ?(continued)

4. One sperm fertilizes the egg, while the other combines with two nuclei in the central cell of the female gametophyte and initiates development of food-storing endosperm

5.The endosperm nourishes the developing embryo

Angiosperm Evolution ?

-Angiosperms originated at least 140 million years ago

-During the late Mesozoic, the major branches of the clade diverged from their common ancestor

-Flowers parts are in 3s(3,6,9 petals)

-one cotyledon

-leaf venation parallel

-Vascular bundles scattered

-Roots fiborous

(Includes grasses, corn, wheat rice)

-Flowers parts in 4's and 5's

-two cotyledon

-Leaf venation"pinnate"

-Vascular Bundles in a cylinder

-Root tap + lateral roots

(include roses, trees, tomatoes, most berrys)

Ch(35)

What are three organ systems of plants? What two systems?

Roots are multicellular organs with important functions:

Anchoring the plant

Absorbing minerals and water

– Storing organic nutrients

A taproot system consists of one main vertical root that gives

 (dicots)

-Adventitious roots arise from stems or leaves 

-Seedless vascular plants and monocots have a fibrous root

In most plants, absorption of water and minerals occurs near

the root hairs, where vast numbers of tiny root hairs increase

the surface area

Vertical=Aerial stem

Horizontal= rhizome

Specialized stems?

Stolons?

Tubers(potato)(food storage)

Bulbs(onions)(food storage)

What does a stem consist of?

A stem is an organ consisting of an alternating system of:

-nodes: the points at which leaves are attached 

-Internodes: the stem segments between nodes

An axillary bud is a structure that has the potential to form a

lateral shoot, or branch

• An apical bud, or terminal bud, is located near the shoot tip

and causes elongation of a young shoot

• Apical dominance helps to maintain dormancy in most

nonapical buds

1. Dermal Tissues(outer protective covering)

2.Vascualar tissues (internal transport)

3.Ground tissues(metabolic function)

- consists of the epidermis

- A waxy coating called cuticle that helps againts water loss

The vascular tissue system carries out long-distance transport

of materials between roots and shoots

• The two vascular tissues are xylem and phloem

• Xylem conveys water and dissolved minerals upward from

roots into the shoots

• Phloem transports organic nutrients from where they are

made to where they are needed

Tissues that are neither dermal nor vascular are the ground tissue system

-Ground tissue internal to the vascular tissue is pith;

-ground -tissue external to the vascular tissue is cortex

-Ground tissue includes cells specialized for storage, photosynthesis, and support

Parenchyma

Collenchyma

Sclerenchyma

Water-conducting cells of the xylem

 Sugar-conducting cells of the phloem

What are characteristics of Parenchyma Cells?

Mature parenchyma cells:

-Have thin and flexible primary walls

• Sclerenchyma cells are rigid because of thick secondary walls strengthened with lignin

• They are dead at functional maturity

• There are two types: – Sclereids are short and irregular in shape and have thick lignified secondary walls

 – Fibers are long and slender and arranged in threads

Characteristics of  Water-Conducting Cells of the Xylem?

The

Thetwo types of water-conducting cells, tracheids and vessel elements, are dead at maturity.

 -Tracheids are found in the xylem of all vascular plants

-Vessel elements are common to most angiosperms and a few

gymnosperms

- Vessel elements align end to end to form long micropipes called vessels

Tracheids =transport and support

Vessel =transport

Fiber =support

Characteristics  of Sugar-Conducting Cells of the Phloem?

-Sieve-tube elements are alive at functional maturity, though they lack organelles

- Sieve plates are the porous end walls that allow fluid to flow between cells along the sieve tube

-Each sieve-tube element has a companion cell whose nucleus

and ribosomes serve both cells

Tissue orgnaization of stems? Where do lateral shoots develop?

In most dicots how is vascular tissue arranged? In monocots how is vascular tissue arranged?

Lateral shoots develop from axillary buds on the stems surface.

-In most dicots the cascular tissue consists of vascular bundles that are arranged in a ring.

-In most monocot stems the vascualr bundles are scattered throughout the ground tissue, rather than froming a ring.

• The epidermis in leaves is interrupted by stomata, which allow

CO2 exchange between the air and the photosynthetic cells in a leaf

• Each stomatal pore is flanked by two guard cells, which regulate its opening and closing

• The ground tissue in a leaf, called mesophyll, is sandwiched between the upper and lower epidermis

What does occurs in the mesophyll layer?

How is the vascular tissue of the stem and leaf related?

• Below the palisade mesophyll in the upper part of the leaf is loosely arranged spongy mesophyll, where gas exchange occurs

• The vascular tissue of each leaf is continuous with the vascular tissue of the stem

• Veins are the leaf’s vascular bundles and function as the leaf’s skeleton

• Each vein in a leaf is enclosed by a protective bundle sheath

- A plant can grow throughout its life; this is called indeterminate growth

• Some plant organs cease to grow at a certain size; this is called determinate growth

• Annuals complete their life cycle in a year or less

• Biennials require two growing seasons

• Perennials live for many years

Meristems are perpetually embryonic tissue and allow for indeterminate growth

• Apical meristems are located at the tips of roots and shoots and at the axillary buds of shoots

• Apical meristems elongate shoots and roots, a process called primary growth(adds vertically)

Lateral meristems add thickness to woody plants, a process called secondary growth

• There are two lateral meristems: the vascular cambium and the cork cambium

• The vascular cambium adds layers of vascular tissue called secondary xylem (wood) and secondary phloem

• The cork cambium replaces the epidermis with periderm, which is thicker and tougher

Meristems give rise to initials, which remain in the meristem,

and derivatives, which become specialized in developing tissues

• In woody plants, primary and secondary growth occur simultaneously but in different locations

Primary growth produces the primary plant body, the parts of

the root and shoot systems produced by apical meristems.

• Growth occurs just behind the root tip, in three zones of cells:

– Zone of cell division

– Zone of elongation

– Zone of maturation

-primary growth of roots produces the epidermis, ground tissue, and vascular tissue

• In most roots, the stele is a vascular cylinder

• The ground tissue fills the cortex, the region between the

vascular cylinder and epidermis

• The innermost layer of the cortex is called the endodermis

-Lateral roots arise from within the pericycle, the outermost cell

layer in the vascular cylinder

• A shoot apical meristem is a dome-shaped mass of dividing cells at the shoot tip

• Leaves develop from leaf primordia along the sides of the apical meristem\

• Axillary buds develop from meristematic cells left at the bases of leaf primordia

• Secondary growth occurs in stems and roots of woody plants but rarely in leaves

• The secondary plant body consists of the tissues produced by the vascular cambium and cork cambium

• Secondary growth is characteristic of gymnosperms and many eudicots, but not monocots

• The vascular cambium is a cylinder of meristematic cells one cell layer thick

• It develops from undifferentiated parenchyma cells

• In cross section, the vascular cambium appears as a ring of initials

• In cross section, the vascular cambium appears as a ring of initials

• The initials increase the vascular cambium’s circumference and add secondary xylem to the inside and secondary phloem to the outside

What accumulates as wood? What is this made of?

What is early wood?

What is late wood?

What can occur to the vascular cambium in temperate regions?

• Secondary xylem accumulates as wood, and consists of tracheids, vessel elements (only in angiosperms), and fibers

• Early wood, formed in the spring, has thin cell walls to maximize water delivery

• Late wood, formed in late summer, has thick-walled cells and contributes more to stem support

• In temperate regions, the vascular cambium of perennials is dormant through the winter

• Tree rings are visible where late and early wood meet, and can be used to estimate a tree’s age

• Dendrochronology is the analysis of tree ring growth patterns, and can be used to study past climate change

•

• As a tree or woody shrub ages, the older layers of secondary xylem, the heartwood, no longer transport water and minerals

• The outer layers, known as sapwood, still transport materials through the xylem

• The cork cambium gives rise to the secondary plant body’s protective covering, or periderm

What does the Periderm consist of?

What does bark consist of?

• Periderm consists of the cork cambium plus the layers of cork cells it produces

• Bark consists of all the tissues external to the vascular cambium, including secondary phloem and periderm

• Lenticels in the periderm allow for gas exchange between living stem or root cells and the outside air

CH(36)

What are the three types of transport in plants?

-Transport of materials into individual cells

– Cell to cell transport

– Long distance transport

Driven by principles of diffusion

– Much of the diffusion is facilitated

– Selective channels are usually gated and regulated

Proton pump

 -Water moves from high to low water potential

 - Water potential = (Psi) and is measured in MPa

– Pure water open to the atmosphere

-Transport proteins in membranes that facilitate the diffusion of water

– Water still diffuses through lipid bilayer

– Aquaporin’s augment water transport Aquaporin’s affect the rate of diffusion but not the water potential gradient or the direction of movement.

-Vascular Membrane that surrounds central vacuole.

– Regulates molecular traffic between the cytosol and the vascular contents (sap)

– Has proton pumps that set up a pH gradient that can move ions across the membrane by chemiosmosis

-generally done by diffusion and movement is from cell to cell

-Xylem water + nutrients

-Symplast transport: water and solutes move along a continuim of cytosol.

-Apoplatstic transport:Water and solutes move along the continium of cell walls and extracellular spaces.

-Transmembrane route= repeated crossings of cellular membranes moving from one to another

The selective permeability of a the plasma membrane controls the movement of solutes into and out of the cell.

-Specific transport proteins are involved in the movement of solutes

Proton pumps create a hydrogen ion gradient that is a form of potential energy that can be harnessed to do work.

Contribute to a voltage known as a membrane
potential.

– The cell will gain water and become turgid

– Healthy plant cells are turgid most of the time

- Bulk Flow

In bulk flow movement of fluid in the xylem and phloem is driven by pressure differences at opposite ends of the xylem vessels and sieve tubes.

-Bulk Flow

-

• Transpiration (evaporation of water from a leaf) reduces
pressure in the leaf xylem. This creates a tension
(negative pressure) that pulls material up the xylem

– Much of the absorption of water and minerals occurs
near root tips, where the epidermis is permeable to
water and where root hairs are located

– Root hairs account for much of the surface area of
roots

Most plants form mutually beneficial relationships with
fungi, which facilitate the absorption of water and
minerals from the soil. Fungi can spread hypha which can absorb more effectivly then roots.

• Roots and fungi form mycorrhizae, symbiotic structures
consisting of plant roots united with fungal hyphae

-Is the innermost layer of cells in the root cortex

– Surrounds the vascular cylinder and functions as the last checkpoint for the selective passage of minerals from the cortex into the vascular tissue

• The waxy Casparian strip made of waxy material suberin of the endodermal wall blocks apoplastic transfer (but not symplastic) of water and minerals from the cortex to the vascular cylinder

-Controls what enters the plant

• Water can cross the cortex via the symplast or
apoplast

•Plants lose an enormous amount of water through transpiration and the transpired water must be
replaced by water transported up from the roots

•Xylem sap rises to heights
of more than 100 m in the
tallest plants

-At night, when transpiration is very low, root
cells continue pumping mineral ions into the
xylem of the vascular cylinder, which lowers
water potential

• Water flows in from the root cortex generating
a positive pressure that forces fluid up the
xylem. This is upward push is called root
pressure

Root pressure sometimes results in guttation,

(the exudation of water droplets on tips of grass blades or
the leaf margins of some small, herbaceous dicots in the
morning). More water enters the leaves than is

transpired, and the excess is forced out of the
leaf.

-Water vapor in the airspaces of a leaf diffuses down its water potential gradient and exits the leaf via stomata.

– Transpiration produces negative pressure (tension) in the leaf which exerts a pulling force on water in the xylem, pulling water into the leaf. This is transmitted all the way from the leaves to the root tips and even into the soil.

– It is facilitated by the cohesion and adhesion properties of water

Stomata help regulate the rate of transpiration

• Leaves generally have broad surface areas and high
surface-to-volume ratios

– These characteristics (1) increase photosynthesis (2)
Increase water loss through stomata

-Organic nutrients are translocated through the phloem (translocation is the transport of organic nutrients in the plant)

– Is an aqueous solution that is mostly sucrose

– Travels from a sugar source to a sugar sink

– A sugar source is a plant organ that is a net
producer of sugar, such as mature leaves

– A sugar sink is an organ that is a net consumer
or storer of sugar, such as a tuber or bulb

•A storage organ such as a tuber or bulb may be a sugar sink in summer as it stockpiles carbohydrates.

•After breaking dormancy in the spring the storage organ may become a source as its stored starch is broken down to sugar and carried away in phloem to the growing buds of the shoot system.

Where must sugar be loaded from and into what?(sap phloem)

Phloem loading requires what? 

-Sugar from mesophyll leaf cells must be loaded into sieve-tube members before being exported to sinks.

• Depending upon the species, sugar moves by symplastic and apoplastic pathways.

-In many plants phloem loading requires active transport.
Proton pumping and cotransport of sucroseand H+ enable the cellsto accumulate sucrose.
.

CH(37Plant nutrition)

What do plants aquire from the soil? What is the majority compostion of plants?

Plants extract from the soil  Mineral nutrients: are essential chemical elements absorbed from soil in the form of inorganic ions.

• For example, plants acquire nitrogen as (NO3-).

-nutrients from soil make only a small contribution to the overall mass of a plant.

• About 80 - 85% of a herbaceous plant is water.

Because water contributes most of the hydrogen ions and some of the oxygen atoms that are incorporated into organic atoms, one can

consider water a nutrient too.

The uptake of nutrients occurs at both the roots and the leaves. Roots, through mycorrhizae and root hairs, absorb water and minerals from the soil. Carbon dioxide diffuses into leaves from the surrounding air through stomata.

Roots are able to absorb minerals somewhat selectively, enabling the plant to accumulate essential elements that may be present in low concentrations in the soil. However, the minerals in a plant reflect the composition of the soil in which the plant is growing. Therefore, some of the elements in a plant are merely present, while others are essential.

A particular chemical element is considered an essential nutrient if it is required for a plant to grow from a seed and complete the life cycle.

Elements required by plants in relatively large quantities are macronutrients. There are nine macronutrients in all, including the six major ingredients in organic compounds: carbon, oxygen, hydrogen, nitrogen, sulfur, and phosphorus.

• The other three are potassium, calcium, and magnesium.

Elements that plants need in very small amounts are micronutrients.  The eight micronutrients are iron, chlorine, copper, zinc, manganese, molybdenum, boron, and nickel. Most of these function as cofactors of enzymatic reactions.

The symptoms of a mineral deficiency depend partly on the function of that nutrient in the plant. Mineral deficiency symptoms depend also on the mobility or immobility of the nutrient within the plant.

Mineral deficiency symptoms depend also on the mobility of the nutrient within the plant. If a nutrient moves about freely from one part of a plant to another, then symptoms of the deficiency will appear first in older organs. Young, growing tissues have more “drawing power” than old tissues for nutrients in short supply. Mobile nutrients include N,P, K, Mg.

If a nutrient is relatively immobile, then a deficiency will affect youngparts of the plant first. Older tissue may have adequate supplies which they retain during periods of shortage. These nutrients include (Fe, Ca, B, S Cu)

The texture and chemical composition of soil are major factors determining what kinds of plants can grow well in a particular location. Plants that grow naturally in a certain type of soil are adapted to its mineral content and texture and are able to absorb water and extract essential nutrients from that soil.  Plants, in turn, affect the soil. The soil-plant interface is a critical component of the chemical cycles that sustain terrestrial ecosystems.

Soil has its origin in the weathering of solid rock. Water that seeps into crevices and freezes in winter fractures the rock, and acids dissolved in the water also help break down the rock. Organisms, including lichens, fungi, bacteria, mosses, and the roots of vascular plants, accelerate the breakdown by the secretion of acids.

topsoil, a mixture of rock, living organisms

 humus, a residue of partially decayed organic material.

-retains water and is porous

-increases soil capacity to exchange cations

-serves as a reservoir of mineral nutrients

The most fertile soils are usually loams, made up of roughly equal amounts of sand, silt (particles of intermediate size), and clay.

After a heavy rainfall, water drains away from the larger spaces of the soil, but smaller spaces retain water because of its attraction for the soil particles, which have electrically charged surfaces. Some water adheres so tightly to hydrophilic particles that it cannot be extracted by plants, but some water bound less tightly to the particles can be absorbed by roots.

 Positively charged mineral ions are made available to the plant when hydrogen ions in the soil displace the mineral ions from the clay particles. This process, called cation exchange, is stimulated by the roots which secrete H+ and compounds that form acids in the soil solution..

Positivly charged ions stick to soil.(cations)

k+, Ca²⁺, Mg²⁺, adhere to soil

-Cations despaced from sopil particles by H+

-Displaced cations enter soil solution

-can be taken up by plant roots

Positively charged mineral ions are made available to the plant when hydrogen ions in the soil displace the mineral ions from the clay particles. This is cation exchange.

What is a component of many redox and lignin biosnythetic enzymes? What type of nutrient is this?

Copper(micro)

-affects chemical form of minerals, affecting cation exchange

-acidic soil has more H+

-H+ displaces mineral cations from soil particles

-cations more avalable in slightly acidic soil

-ccations leached out of highly acidic soil

-toxic Al³⁺ release if Ph<5(acid rain)

• Plants cannot use nitrogen in the form of N2.

• It must first be converted to ammonium (NH4+) or nitrate (NO3

• In the short term, the main source of nitrogen is the decomposition of humus by microbes, including ammonifying bacteria.

• Nitrogen is lost from this local cycle when soil microbes called denitrifying bacteria converts NO3

Other bacteria, nitrogen-fixing bacteria, restock nitrogenous minerals in the soil by converting N2 to NH3 (ammonia), via nitrogen fixation.

these include several species of free-living bacteria and

several others that live in symbiotic relationships with plants.

• The reduction of N2 to NH3 is a complicated, multi-step process, catalyzed by one enzyme complex, nitrogenase:

• N2 + 8e- + 8H+ + 16ATP -> 2NH3 + H2 + 16ADP + 16Pi

Many plant families include species that form symbiotic relationships with nitrogen-fixing bacteria. This provides their roots with a built-in source of fixed nitrogen for assimilation into organic compounds.  A legume’s roots have swellings called nodules, composed of plant cells that contain nitrogen-fixing bacteria of the genus Rhizobium.

Mycorrhizae (“fungus roots”) are modified roots, consisting of symbiotic associations of fungi and roots. The symbiosis is mutualistic. The fungus benefits from a hospitable environment and a steady supply of sugar donated by the host plant. The fungi provide several potential benefits to the host plants including increased surface area for water uptake and mineral absorption.

This plant-fungus symbiosis may have been one of the evolutionary adaptations that made it possible for plants to colonize land in the first place. Fossilized roots from some of the earliest land plants include mycorrhizae. Mycorrhizal fungi are more efficient at absorbing minerals than roots, which may have helped nourish pioneering plants, especially in the nutrient-poor soils present when terrestrial ecosystems were young.

In ectomycorrhizae, the mycelium forms a dense sheath over the surface of the root and some hyphae grow into the cortex in extracellular spaces between root cells.(do not penetrate root cells

In endomycorrhizae, the fungus makes extensive contact with the plant through branching of hyphae (arbuscles) that form invaginations in the host cells, increasing surface area for exchange of nutrients.(dont penetrate cell membrane)

1.Infection

-roots attract bacteria

-infection thread forms

2. Nodule formed

3.Vascular connection

An epiphyte is an autotrophic plant that nourishes itself but grows on the surface of another plant, usually on the branches or trunks of trees. While an epiphyte is anchored to its living substratum, it absorbs water and minerals mostly from rain that falls on its leaves.

Living in acid bogs and other habitats where soil conditions are poor are plants that fortify themselves by occasionally feeding on animals. These carnivorous plants make their own carbohydrates by photosynthesis, but they obtain some of their nitrogen and minerals by killing and digesting insects and other small animals.

(CH38)

What is a complete plant compared to an incomplete plant?

Complete:Has all 4 parts (sepals, petals, stamens, carpels)Incomplete: Missing one or more parts

– Bisexual (“perfect”) flower: has both stamens

and carpels

– Unisexual (“imperfect”) flower: missing either

stamens or carpels

• Staminate: has stamens

• Carpelate: has carpe

I.              Describe Sexual Reproduction in angiosperms?

Sporophyte and gametophyte generations alternate in the life cycles of plants (review) Sporophyte is dominant stage in angiosperms Spores undergo mitotic division and develop into multicellular male or female gametophytes. Gametophytes produce gametes by mitosis and gametes fuse to form a zygote that develops into a multicellular sporophyte. Gametophyte is dependent on the sporophyte

Male and female gametophytes develop within the anthers and ovaries. Flowers develop from compressed shoots. Stamen and Carpel contain sporangia. Female gametophytes develop in carpel sporangia as embryo sac (contains eggs). This occurs in the ovules in the ovaries. Male gametophytes develop in the stamen sporangia as pollen grains and form at the anthers.

1.Pollination occurs, 2. Pollen tube grows from pollen grain into embryo sac,3. sperm discharged and fertilize egg, 4.Zygote becomes embryo (2n), 5.other sperm becomes endosperm when fertilizing two central nuclei + 6.developing zygote form the seed,7. Entire ovary develops into a fruit. 8. seed is disperesed.

-Pollen Grain

-Anther consist fo 4 microsporaniga. Microsporangia produce diploid microsporocytes. Diploid microsporocytes (in anther) undergo meiosis forming 4 haploid microspores, which develop into the pollen grain. Each microspore divides by mitosis to make two cells one tubecell and one generative cell. Wall of microspore thickens to form mature pollen grain. (male gametophyte)

-Embryo Sac

-Ovules develop with chambers of ovary: each ovule has a single sporangium.Megasporocyte (in ovule) undergoes meiosis and makes 4 haploid megaspores (only one survives). Remaining megaspore grows and its nucleus undergoes 3 mitotic divisions resulting in formation of 8 haploid cells (nuclei). Membranes partition this into a multicellular embryo sac. Egg is located at one end, flanked by two cells called synergids. Two polar nuclei are in center and share a compartment.Three antipodal cells are on opposite side of egg (function unknown). Micropyle (opening near egg) allows pollen tube to enter.

-   Maturation of stamens and carpels at different times  

      - Biochemical blocks to own pollen grains                                       

- Flower design may block pollen from same flower

Describe Double Fertilization?

Upon entry, generative nucleus divides by mitosis forming two sperm. One sperm unites with egg and 2N zygote results .Remaining sperm unites with the two polar nuclei resulting in 3N endosperm (food storing tissue)

Describe   Endosperm development?

Begins before embryo development. It forms a milky, multinucleate supercell that becomes multicellular. In most monocots, it stocks nutrients that are used after germination begins. In many dicots, endosperm nutrients are sent to the cotyledons; mature seeds have no endosperm left.

Members of grass have sepcialized ctoyledon called scutellum. Embryo is enclosed by two sheaths a

-coleorhiza: which covers the young root 

 coleoptile: which covers the young shoot

1. True fruit is a ripened ovary.2. Pollination triggers hormonal changes that cause ovary to grow. 3. Wall thickens to become pericarp 4.In most plants, fruit does not develop without fertilization of ovules. 5. Fruits ripen about same times seeds are fully developed

What are seed dormancy adaptions?

Prevents germination when conditions are not favorable.

Conditions for breaking dormancy vary in desert plants it may require lots of rain. Other plants exposure to cold, sunlight, or passage through a digestive tract may be necessary.

Viability time varies (most for a year or two) providing a pool of ungerminated seeds in the soil (after an environmental disruption, may provide rapid vegetation)

a.Imbibition (absorption of water) b.Seed swells and ruptures seed coat c. Metabolic changes in embryo stimulate growth d.Endosperm and/or cotyledon nutrients are digested by enzymes and nutrients are delivered to embryo plant e.Radicle emerges f. Shoot tip breaks through soil g Light stimuates hypocotyls to straighten h Epicotyl spreads and cotyledons will turn green

Many plants can clone themselves. It is the production of offspring from single parent.

  Fragmentation – separation of parent plant into parts ( Most common form of vegetative propagation)

   Apomixis – production of seeds without meiosis and fertilization.  The diploid cell in ovule makes embryo. Ovule matures into seeds and are dispersed(Ex. Dandelion) 

-provides variation in environment with evolving pathogens

-can disperse seed to new locations and wait till hostile conditions improve to grow

Costs: more energetically costly to produce seeds

Benefits:-plant well suited to a particular environment can clone many copies of itself rapidly.

-offspring of fragmentation are not as frail as seedling allowing them to take over an area.

Cost: There is little genetic variability. One disease could wipe out the entire variety.

Combining two parts of plants to make more successful plant. The Plant fragments are called callus. The plants modified by taking stock (plant that provided roots) and the twig grafted two the stock is called a scion.

Benefits:

-Plant growth is uniform

-Fruits ripen in unison

-Crop yields are dependable

Risks:

-Little genetic variability

-One disease could wipe out the entire variety

(Ch39 Plant responses to internal and external stimulii)

What is greening?

Greening is the elongation rate of stems slowing. The leaves expanding. The roots elongating while the shoot begins to produce Chlorophyll

-produced in low concentrations

-control plant growth and development by affecting cell division, cell elongation and cell differentiation.

-Stimulates cell elongation through loosening of cell walls

-involved in root formation and branching

-affects secondary growth by inducing cell division in vascular cambium.   

-Also influence differentiation of secondary xylem.

.

-it is a synthetic auxin that disrups plant growth in high concentrations. Some plants are more sensative then others.

(agent orange)

-modified form of adenine

-stimulates cell division

-interacts with auxin to control plant growth

-produced by roots

-zeatin is an example of this hormone

How to Cytokinins and Auxins control apical dominance?

-Cytokinins come from roots and signal axillary buds to grow(counter auxin causing lateral growth.

-auxin transported down the shoot inhibiting axillary bud growth causing terminal buds growth to occur(ie causing the shoots to lengthen)

-either lateral growth (cytokinins) or vertical growth(auxin)

*apical dominance can be restored by adding auxin to stems

-discovered in Japan

-stimulate elongation(partner with auxin)

-stimulate seed germenation

-promote fruit growth(fruit grow larger in size)

-100+ different kinds isolated

-hormone that slows growth

-induces dormancy, causes stomata to close in drought

- a gas

-causes senescence(aging in plants)

-fruit ripening

-leaf abscission(loss of leaves)

-located at leaf base

-special layer of cells separate leaf; protecting stem

-when auxin levels are low cells are more sensitive to ethylene

-Can be cause from a stress response(drought, flooding, injury) which can lead to apoptosis(programmed cell suicide)

Triple response: is if a obstacle is in the way of a stem growing such as rock ti will grow around it.

1. slowing of stem elongation

2.thickening of stem

2. curvature that causes stem to grow horizontally

What is a Gravitropism?

-if plants lay on their side roots show down and up (directions will change)

-plants detect gravity by Statoliths

-specialized plastids comprise of dense starch grains

Mutant starchless plants slightly respond to gravity without Statoliths because gravity detection is also mediated by auxin.

What is a Thigmotropism?

-plant growth in response to touch

-occurs in vines and other climbing plants (cling to surfaces)

-Rapid leaf movement in response to stimuli. Cause by changes in turgor pressures.

-plants detect light and dark periods

-fist discovered in the 1920’s, plants that only flowered if day were less than 14 hours called short day plants

-other species called long day plants (more than 14 hours) and day neutral plants

-Short day plants are really long night plants because light in the night causes them to stop flowering.

-Long day plants are really short night plants because they will not flower if nights are too long but will flower if nights are interrupted by light

-Red light changes  P_r  to P_Fr

-Far red light changes P_Fr to P_r 

 -P_Fr activates germentation

-Balances controls of flowering

- some plants flower after a single exposure to required photo period

-some plants need successive days of required photoperiod

-some plants need environmental stimulus + required photo-period

-example Arabidopsis Thalma(requires pretreatment of cold to induce flowering(vernalization)

Plants counter herbivores with physical defenses such as thorns and chemical defenses.

-some poison insects or give off bad tastes if eaten

-others recruit animals to help protect it

-example plant in respond to saliva from catipiller release chemical that causes a certain species of wasps to lay eggs in the catipiller. The larvae eat through the catipiller killing it.