CHAPTER 28: GREEN ALGAE AND LAND PLANTS

EVOLUTIONALY SEQUENCE OBSERVED IN WATER-CONDUCTING CELLS Simple Water-Conducting Cells

*Elongated cells with little structural support *Found in fossils and present-day mosses *Primary wall (with cellulose)

Angiosperms (Flowering plants)

*Most diverse plants living today *STAMEN contains ANTHER where microsporangia develop *CARPEL contains OVARY where ovules (contain the megasporangia) are found

EVOLUTIONALY SEQUENCE OBSERVED IN WATER-CONDUCTING CELLS: First Vascular Tissue

*Some structural support *Found in fossils *Primary wall (with cellulose) *Lignin (deposited with rings)

EVOLUTIONALY SEQUENCE OBSERVED IN WATER-CONDUCTING CELLS: Vessel Elements

*Xylem cells *More advanced, more abundant *Primary wall (with cellulose) *Secondary wall (with lignin) *Sides have pits *Ends have perforations, where both primary and secondary cell walls are absent *Drop leaves and go dormant in winter *More efficient *ANGIOSPERMS

What was the seemingly first evolutionary change necessary for plants to adapt to living on land?

Developing a waxy covering

Nonvascular plants

Don't have a phloem or xylem; limited in range/distribution *Lack vascular tissue (Specialized groups of cells that conduct water or dissolved nutrients throughout the plant body) *Include mosses (dependent on water, do well in high moisture conditions) *Use spores, not seeds for reproduction and dispersal PARAHYLETIC

Structure of a seed

(OUTSIDE) Seed Coat (MIDDLE) Nutritive Tissue (INSIDE) Embryo

EVOLUTIONALY SEQUENCE OBSERVED IN WATER-CONDUCTING CELLS: Tracheids

*All vascular plants have tracheids *Xylem cells *Much lower resistance to flow *Increased structural support *Found in all vascular tissue *Primary wall *Secondary wall *Ends and sides have pits, where secondary cell wall is absent *Cavitation event/embolism: gas bubble that limits conduction *Do well in freeze thaw events *GYMNOSPERMS

Double Fertilization

*Angiosperm fertilization involves two sperm cells -One fuses with egg to form a diploid (2n) zygote -One fuses with two nuclei in the female gametophyte -Forms a triploid (3n) nutritive tissue (endosperm) that grows around the zygote

Comparison between Green Algae and Land Plants

*CHLOROPLAST (Structure is the same; Allow for photosynthesis to take place; Synthesize starch as a storage product) *THYLAKOID (Arrangements are similar; In the chloroplast there are stacks of thylakoid membranes where chlorophyll molecules are found) *CELL WALLS, SPERM AND PEROXISOMES (Peroxisomes are certain compounds that are enzymatic and break things down; others are similar in structure and composition)

ALTERATION OF GENERATIONS: Zygotes

*Diploid *Result from the fusion of two haploid cells, such as a sperm and an egg *Spores are produced by meiosis inside of the sporangia *Gametes are produced by mitosis inside of the gametangia

Many pharmaceuticals have been derived from land plants. These chemicals are used in plants mainly as _____.

Defense against herbivores and parasites

TWO TYPES OF SPORE-PRODUCING STRUCURES IN HETEROSPOROUS SPECIES: 1.) Microsporangia 2.) Megasporangia

1.) MICROSPORANGIA: Produce microspores that develop into male gametophytes and produce small gametes (sperm) Microsporangia --> Microspores --> Male gametophyte --> Sperm 2.) MEGASPORANGIA: Produce megaspores that develop into female gametophytes which produce large gametes (eggs) Megasporangia --> Megaspores --> Female gametophyte --> Eggs Seed plants are HETEROSPOROUS SPECIES

Angiosperms have been divided into two major groups

1.) Monocotyledons (Monocots) *Have one cotyledon *Monophyletic 2.) Dicotyledons (Dicots) *Have two cotyledon *Paraphyletic

Fossil Record of Land Plants

1.) Origin of Land Plants --> 2.) Silurian-Devonian Explosion --> 3.) Carboniferous Period--> 4.) Diversification of Gymnosperms --> 5.)Diversification of Angiosperms

Plant reproduction in dry conditions

1.) SPORES: That resist drying because they are encased in tough coat of sporopollenin 2.) GAMETES: Produced in complex, multicellular structures 3.) EMBRYOS: Retained on and nourished by parent plant

ALTERATION OF GENERATIONS: Sequence of events

1.) SPOROPHYTE: Produces haploid spores by meiosis 2.) SPORES: Germinate and divide by mitosis and develop into multicellular haploid gametophytes 3.) GAMETOPHYTES: Produce unicellular haploid gametes by mitosis 4.) Two gametes unite during fertilization to form a diploid zygote 5.) Zygote divides by mitosis and develops into a multicellular DIPLOID SPOROPHYTE A back and forth cycle between the HAPLOID GAMETOPHYTE STAGE and the DIPLOID SPOROPHYTE STAGE. One stage will be more dominant than the other (meaning it spends more time in that stage)

The diversification of angiosperms is associated with three key adaptions

1.) Water conducting vessels (xylem vessels) 2.) Flowers 3.) Fruits These adaptions allow angiosperms to transport water, pollen and seeds efficiently

You see a megasporangium. You are most likely examining the reproductive structures of _______

A pine cone

Style

Above the ovary

Homosporous

All nonvascular plants and most seedless vascular plants Production of a single type of spore Spores will develop into bisexual gametophyte that produces both eggs and sperm

An ecosystem consists of

All organisms in a particular area; biotic and abiotic features of that area. Nonliving physical components include: *Atmosphere *Percipitation *Surface water *Sunlight *Soil *Nutrients

Why is it obvious that tall corn plants seen from a car window do not belong to the bryophyte lineage?

Bryophytes lack vascular tissue and grow close to the ground.

Fossil Record

Determine what species were present at different times and how they evolved

Land plants have an important function which is

Converting energy in sunlight into chemical energy through photosynthesis. They fix more CO2 than they release, carbon comes in through the stomata on the underside of the leaf while inorganic molecules come through the root

Bryophytes (Mosses) are

DIOECIOUS: Male and female individual plants *MALE: Antheridia; store the gametes *FEMALE: Archegonia; contain egg cells

Pistol

Female reproductive structure

Plants provide humans with

Food, Fuel, Fiber and Building Materials and medicine

Sepals

Form to support the flower and the petals

Bryophytes have a ________-________ life cycle

Gametophyte-Dominant

A plant with the most efficient water transport should have cells with ________

Gaps in the ends of the cells where both the primary and secondary cell walls are missing

ALTERATION OF GENERATIONS: Sporophyte

Generate spores which then produce gametophytes

Seedless Vascular Plants

Have phloem and xylem *Have well developed vascular tissue *Do not make seeds; use spores for reproduction *Includes ferns (Dependent on water + Moisture, thrive in shaded regions) PARAPHYLETIC

Seed Plants

Have vascular tissue *Make seeds (Seeds consist of an embryo and nutritive tissue, surrounded by a tough protective layer) *Include Angiosperms (Flowering plants; "encased seeds") and Gymnosperms (Conifers; "Naked seeds") MONOPHYLETIC

Homologous charactersistics

Having a common origin, can be traced back to a similar ancestor, they have similar genetics

Monoecious

Having both male and female reproductive organs

Green Algae

Important photosynthetic organisms in freshwater habitats

ALTERATION OF GENERATIONS: Individuals will have *Multicellular ________ phase called the gametophyte *Multicellular ________ phase known as the sporophyte

Individuals will have *Multicellular HAPLOID phase called the gametophyte *Multicellular DIPLOID phase known as the sporophyte

As an introductory biology student, you know that angiosperms are unique among plants in that they produce fruits and flowers. How else could you be sure that a plant is an angiosperm?

Its seeds are inside an encapsulated structure

Land Plants

Key photosynthesizers in terrestrial environments

ALTERATION OF GENERATIONS: Gametophytes

Make gametes, gametes fuse to form a zygotes which then produce a sporophyte

What is the chronological order of adaptive features of land plants?

The transition of plants from freshwater environments occurred before the adaptation to living on land.

What adaptation reduced the dependence of seed plants on water for fertilization?

Pollen Grains

Heterospory

Production of two distinct types of spores by different structures

Phylogenetic Trees

Putting it all together; the relationships between species based on DNA sequences

You find an undescribed plant. It has small, free-living gametophytes and large, longer-lived sporophytes. You also observe that dispersal is carried out using spores. You thus conclude that your discovery is a _____.

Seedless vascular plant

Ferns and other vascular plants have a _________-_________ life cycle

Sporophyte-Dominant (More advantageous, diploid cells can respond better to varying environmental conditions)

Morphological Traits

Structural features

Ovary

Swollen base where the egg is found

What major evolutionary trends in green plants are supported by the order in which distinct plant taxa are found in the fossil record?

The evolution of land plants from green algae and the gradual evolution of traits that reduce the dependence of land plants on wet environments

Analogous Traits

They appear to have similar morphological traits but genetically they are very different

Stamen

The male reproductive part of the flower which consists of a filament

Anther

The production of a male gametophyte (which is the pollen)

Adaptive Radiation

The relationship with animals that lead to success Occurs when an animal enters a new habitat and different traits affect its survivability Angiosperms

What is an accurate description of tracheids?

Tracheids lack cytoplasm

Green Algae include species that are:

Unicellular or multicellular Colonial Live in marine, freshwater, or moist terrestrial habitats They are protists that are the ancestors of all land plants

Stigma

Very top, above the style where pollen gets develops

Which pair of characteristics is used to define the three categories into which land plants are classified?

Whether the plants contain vascular tissue and whether they produce seeds

Which of the following statements about seed plants is true? a) Angiosperms have more species diversity than other taxa of land plants. b) Gymnosperms have more species diversity than other taxa of land plants. c) Seed plants lack vascular tissue. d) Angiosperms produce "naked seeds."

a) Angiosperms have more species diversity than other taxa of land plants.

Select the correct statement about green algae. a) Some green algae form stable associations called lichens with fungi. b) Green algae have chloroplasts but lack mitochondria. c) Green algae are important primary producers only in nearshore ocean environments. d) Green algae synthesize starch in the mitochondria as a storage product of photosynthesis.

a) Some green algae form stable associations called lichens with fungi.

Biologists hypothesize that the first land plants had a low, sprawling growth habitat. Which of the following statements support this hypothesis? a) Low, sprawling growth protected the first land plants from herbivores. b) To obtain water, the first land plants had to keep their tissues in direct contact with moist soil. c) The low, sprawling growth increased the surface area of the first land plants, providing them with additional light for photosynthesis. d) The wind speed was much greater at that time than it is now, restricting the height of the first land plants.

a) To obtain water, the first land plants had to keep their tissues in direct contact with moist soil.

Which of the following choices properly pairs the ploidy of the gametophyte with the ploidy of the gamete? a) Diploid gametophytes produce diploid gametes. b) Haploid gametophytes produce haploid gametes. c) Diploid gametophytes produce haploid gametes. d) Haploid gametophyte produces diploid gametes.

b) Haploid gametophytes produce haploid gametes.

Which of the following statements best supports the hypothesis that flowers of angiosperms are adaptations that increase fertilization success in terrestrial environments? a) The evolution of the flower increased the success of wind pollination. b) Heterospory—the production of two distinct types of spores by different structures—is unique to angiosperms. c) Flowers attract pollinators to increase pollination success. d) Flowers are adaptive because they produce endosperm, which protects the female gametophyte from predators.

c) Flowers attract pollinators to increase pollination success.

Which of the following groups of green plants is a monophyletic group? a.) Non-vascular plants b.) Seedless vascular plants c.) Gymnosperms d.) Green algae

c.) Gymnosperms

Which of the following is the most accurate example of the direct-pollination hypothesis? a) Flowers pollinated by hummingbirds are generally white, as hummingbirds lack color vision. b) Bee-pollinated flowers have long, tubular structures to protect the bees. c) Brightly colored flowers are pollinated by moths, which are attracted to bright colors. d) Carrion flowers produce molecules that smell like rotting flesh to attract flies.

d) Carrion flowers produce molecules that smell like rotting flesh to attract flies.