Plant APBio

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Information about Plant APBio

Published on February 28, 2008

Author: MrDPMWest

Source: slideshare.net

The Plant Kingdom

Key Features of Plants Multicellularity Ability to photosynthesize (most) Exhibit alternation of generations (a multicellular diploid generation alternates with a multicellular haploid generation)

Multicellularity

Ability to photosynthesize (most)

Exhibit alternation of generations (a multicellular diploid generation alternates with a multicellular haploid generation)

Alternation of Generations Diploid sporophyte plant produces haploid spores through meiosis Spores divide by mitosis and develop into haploid gametophyte plants Haploid gametophyte plant produces haploid gametes through mitosis Gametes fuse to form diploid zygotes , which divide by mitosis and develop into diploid sporophytes

Diploid sporophyte plant produces haploid spores through meiosis

Spores divide by mitosis and develop into haploid gametophyte plants

Haploid gametophyte plant produces haploid gametes through mitosis

Gametes fuse to form diploid zygotes , which divide by mitosis and develop into diploid sporophytes

Alternation of Generations in Plants Gametophytes form by meiosis Spores form by meiosis n n n Spore Mother Cell Egg Sperm Gametes meet & fuse to form zygote Zygote Embryo Sporo- phyte 2 n Spores n Gameto- phyte 2 n n n 2 n 2 n 2 n Haploid Diploid

Evolution of Plants The evolutionary origin of plants Division Rhodophyta—red algae Division Phaeophyta—brown algae Division Chlorophyta—green algae and the origin of land plants

The evolutionary origin of plants

Division Rhodophyta—red algae

Division Phaeophyta—brown algae

Division Chlorophyta—green algae and the origin of land plants

Green Algae Several lines of evidence support the hypothesis that green algae gave rise to plants DNA comparisons show that green algae are plants’ closest living relatives Both use the same type of chlorophyll and accessory pigments in photosynthesis Both store food as starch Both have cell walls made of cellulose

Several lines of evidence support the hypothesis that green algae gave rise to plants

DNA comparisons show that green algae are plants’ closest living relatives

Both use the same type of chlorophyll and accessory pigments in photosynthesis

Both store food as starch

Both have cell walls made of cellulose

Fresh Water Ancestors Most green algae live in fresh water, suggesting that early plants evolved in freshwater habitats Early green algae must have evolved characteristics to withstand the challenges of fresh water habitats, e.g. temperature extremes, periods of dryness These adaptations provided a foundation for descendants to evolve traits for life on land

Most green algae live in fresh water, suggesting that early plants evolved in freshwater habitats

Early green algae must have evolved characteristics to withstand the challenges of fresh water habitats, e.g. temperature extremes, periods of dryness

These adaptations provided a foundation for descendants to evolve traits for life on land

The Evolution of Land Plants Roots and rootlike structures (anchor & absorb) Vascular tissue for transport of water & nutrients Stiffening substance (lignin) for support Waxy covering (cuticle) limits evaporation Stomatal pores Mediate gas exchange Regulate water vapor loss Evolutionary adaptations in plant reproduction Early algae relied on water currents for fertilization Dry land adaptation include the generation of pollen, seeds, flowers, and fruit… Adaptations in the alternation of generations…

Roots and rootlike structures (anchor & absorb)

Vascular tissue for transport of water & nutrients

Stiffening substance (lignin) for support

Waxy covering (cuticle) limits evaporation

Stomatal pores

Mediate gas exchange

Regulate water vapor loss

Evolutionary adaptations in plant reproduction

Early algae relied on water currents for fertilization

Dry land adaptation include the generation of pollen, seeds, flowers, and fruit…

Adaptations in the alternation of generations…

Reproduction Without Water Pollen A reduced male gametophyte that allows wind (instead of water) to carry sperm to eggs Seeds Nourish, protect, and help disperse developing embryos Flowers Attract pollinators Fruits Attract animals to disperse seeds

Pollen

A reduced male gametophyte that allows wind (instead of water) to carry sperm to eggs

Seeds

Nourish, protect, and help disperse developing embryos

Flowers

Attract pollinators

Fruits

Attract animals to disperse seeds

Major Groups of Plants Bryophytes ( nonvascular plants ) Lack well-developed structures for conducting water and nutrients Tracheophytes ( Vascular plants ) Have a complex vascular system

Bryophytes ( nonvascular plants )

Lack well-developed structures for conducting water and nutrients

Tracheophytes ( Vascular plants )

Have a complex vascular system

Evolutionary Tree of Major Plant Groups Ancestral Algae Liver- worts Mosses True vascular tissue & lignin appear Ferns Gymno- sperms Seeds and pollen appear Flowers & Fruits appear Angio- sperms Bryophytes Seed Plants Tracheophytes

The Bryophytes Nonvascular plants No true roots, leaves, and stems Still require a moist environment Anchoring rhizoids absorb water & nutrients Reproductive structures protect gametes Still depend on water for fertilization Dominant gametophyte generation

Nonvascular plants

No true roots, leaves, and stems

Still require a moist environment

Anchoring rhizoids absorb water & nutrients

Reproductive structures protect gametes

Still depend on water for fertilization

Dominant gametophyte generation

Liverworts & Mosses Liverworts Female Gametophyte Archegonium (a) Mosses Female Gametophytes Sporophytes (b)

The Bryophytes: Reproduction Gametes develop within protected structures on gametophyte Archegonia (singular, archegonium) produce eggs Antheridia (singular, antheridium) produce sperm Archegonia and antheridia may be located on the same plant or on different plants

Gametes develop within protected structures on gametophyte

Archegonia (singular, archegonium) produce eggs

Antheridia (singular, antheridium) produce sperm

Archegonia and antheridia may be located on the same plant or on different plants

Life Cycle of a Moss (a) Zygote develops into sporophyte within gametophyte Sporophyte Capsule Fertilization Meiosis Haploid spores liberated from sporophyte capsule Old Gametophyte Spores disperse and germinate Haploid 1 n Diploid 2 n

Life Cycle of a Moss (b) Haploid 1 n Diploid 2 n Spore germinates into gametophyte Leafy Gametophyte Archegonium produces egg Antheridium produces sperm Sperm swim to egg Fertilization

The Vascular Plants Have roots, stems, and leaves Have vessels impregnated with the stiffening agent lignin Sporophyte generation is dominant Include the seedless vascular plants and the seed plants

Have roots, stems, and leaves

Have vessels impregnated with the stiffening agent lignin

Sporophyte generation is dominant

Include the seedless vascular plants and the seed plants

Division Tracheophyta: Vascular Plants Adapted to life in drier conditions Had to generate body support Vessels to conduct water and nutrients A stiffening substance called lignin Seedless plants: club mosses, horsetails, and ferns Sporophyte generation more dominant Fertilization still relies on water

Adapted to life in drier conditions

Had to generate body support

Vessels to conduct water and nutrients

A stiffening substance called lignin

Seedless plants: club mosses, horsetails, and ferns

Sporophyte generation more dominant

Fertilization still relies on water

Life Cycle of Ferns (a) Haploid 1 n Diploid 2 n Gametophyte Sporophyte develops from gametophyte Root Stem Sporophyte Masses of Sporangia Meiosis Haploid spores liberated from sporangium Sporangium

Life Cycle of Ferns (b) Haploid 1 n Diploid 2 n Haploid spores liberated from sporangium Spores disperse & germinate Gametophyte Archegonium produces egg Antheridium produces sperm Sperm swim to egg Fertilization

Seedless Plants Club Mosses Horsetails Ferns

Seed Plants: General Dominance of the sporophyte generation Reproductive adaptations Pollen Wind and pollinators for fertilization Water not required for fertilization Seeds Stores food for embryo Embryo protection for unfavorable environments

Dominance of the sporophyte generation

Reproductive adaptations

Pollen

Wind and pollinators for fertilization

Water not required for fertilization

Seeds

Stores food for embryo

Embryo protection for unfavorable environments

Seeds (a) Gymnosperm (d) Water Dispersal (c) Wind Dispersal Stored Food Embryo Seed Coat (b) Angiosperm

Seed Plants: Gymnosperms Nonflowering seed plants Produce "naked seeds" Three divisions: Coniferophyta Cycadophyta Ginkgophyta Conifers are adapted to dry, cold conditions Thin, waterproof needles to decrease evaporation Evergreen; year-round photosynthesis Produce an "antifreeze" substance in sap

Nonflowering seed plants

Produce "naked seeds"

Three divisions:

Coniferophyta

Cycadophyta

Ginkgophyta

Conifers are adapted to dry, cold conditions

Thin, waterproof needles to decrease evaporation

Evergreen; year-round photosynthesis

Produce an "antifreeze" substance in sap

Two Uncommon Gymnosperms (a) Gingko (b) A Cycad – either male or female

Gymnosperms: Conifers Adapted to dry, cold conditions: Retain green leaves throughout the year (evergreen) Thin, needle-like leaves covered with waterproofing material to reduce evaporation Produce an “antifreeze” in sap

Adapted to dry, cold conditions:

Retain green leaves throughout the year (evergreen)

Thin, needle-like leaves covered with waterproofing material to reduce evaporation

Produce an

“antifreeze” in sap

Life Cycle of the Pine (a) Haploid 1 n Diploid 2 n Mature Sporophyte Seedlings (Sporophyte) Male Cone Male Scale MEIOSIS Male gametophytes (pollen) liberated Female Cone Female Scale Ovule Spore-forming Cell MEIOSIS

Life Cycle of the Pine (b) Haploid 1 n Diploid 2 n MEIOSIS Pollen liberated; Dispersed by wind MEIOSIS Seedlings (Sporophyte) Egg Cell Female Gametophyte Pollen lands on female scale Pollen Tube FERTILIZATION Seed Embryo

Seed Plants: Angiosperms Flowering seed plants The dominant plant form on Earth Major evolutionary adaptations Flowers to attract pollinators Fruit to protect seeds and developing embryo Broad leaves Increase photosynthesis during the growing season Shed during periods of cold and drought

Flowering seed plants

The dominant plant form on Earth

Major evolutionary adaptations

Flowers to attract pollinators

Fruit to protect seeds and developing embryo

Broad leaves

Increase photosynthesis during the growing season

Shed during periods of cold and drought

Monocot vs Dicot Class Monocotyledoneae (monocots): grasses, grains, corn 1 cotyledon leave veins in parallel lines Flower parts, in multiple of 3 scattered vascular bundles Class Dicotyledoneae (dicots): hardwood trees, shrubs, and herbs 2 cotyledons, web-like veins, flower petals in 4/5s, ringed vascular bundles

Class Monocotyledoneae (monocots): grasses, grains, corn

1 cotyledon

leave veins in parallel lines

Flower parts, in multiple of 3

scattered vascular bundles

Class Dicotyledoneae (dicots): hardwood trees, shrubs, and herbs

2 cotyledons, web-like veins, flower petals in 4/5s, ringed vascular bundles

 

Flowers Flowers are reproductive structures in which both male and female gametophytes are formed Believed to have evolved when gymnosperm ancestors formed an association with animals Animals benefited by eating some of the protein-rich pollen Plants benefited by using animals as pollinators Most flowers are showy and attract animal pollinators (e.g. insects)

Flowers are reproductive structures in which both male and female gametophytes are formed

Believed to have evolved when gymnosperm ancestors formed an association with animals

Animals benefited by eating some of the protein-rich pollen

Plants benefited by using animals as pollinators

Most flowers are showy and attract animal pollinators (e.g. insects)

Life Cycle of a Flowering Plant (a) Fruit Seed Food Embryo Seed Coat Seedling Flower Anther MEIOSIS Ovary Ovule Spore-forming Cell Haploid 1 n Diploid 2 n

Life Cycle of a Flowering Plant (b) Fruit MEIOSIS MEIOSIS Spore Female Gametophyte Egg Cell Pollen (male gametophyte) Stigma Pollen Tube Sperm Nuclei FERTILIZATION Haploid 1 n Diploid 2 n

Fruits Encourage Seed Dispersal Fruits are mature ovaries that contain developing seeds Various fruit adaptations help disperse seeds Edible fruits entice animals to eat them (seeds pass through digestive tract unharmed) Burrs cling to animal fur Winged fruits are carried through the air

Fruits are mature ovaries that contain developing seeds

Various fruit adaptations help disperse seeds

Edible fruits entice animals to eat them (seeds pass through digestive tract unharmed)

Burrs cling to animal fur

Winged fruits are carried through the air

Broad Leaves Broad leaves of angiosperms collect more sunlight for photosynthesis than narrow leaves of gymnosperms Temperate angiosperms drop leaves to conserve water when it is in short supply (fall, winter) Tropical and subtropical angiosperms are evergreen May shed leaves during dry season

Broad leaves of angiosperms collect more sunlight for photosynthesis than narrow leaves of gymnosperms

Temperate angiosperms drop leaves to conserve water when it is in short supply (fall, winter)

Tropical and subtropical angiosperms are evergreen

May shed leaves during dry season

Broad Leaves Photosynthetic advantage is offset by fact that broad, tender leaves are more appealing to herbivores than tough, waxy needles of conifers Angiosperm defenses include Physical defenses (thorns, spines, resins) Chemical defenses (make plant tissue poisonous or distasteful)

Photosynthetic advantage is offset by fact that broad, tender leaves are more appealing to herbivores than tough, waxy needles of conifers

Angiosperm defenses include

Physical defenses (thorns, spines, resins)

Chemical defenses (make plant tissue poisonous or distasteful)

Crucial Ecological Role Through photosynthesis, plants provide food, directly or indirectly, for all of the animals, fungi, and non-photosynthetic microbes on land Plants produce oxygen gas as a byproduct of photosynthesis, continually replenishing oxygen in the atmosphere

Through photosynthesis, plants provide food, directly or indirectly, for all of the animals, fungi, and non-photosynthetic microbes on land

Plants produce oxygen gas as a byproduct of photosynthesis, continually replenishing oxygen in the atmosphere

Crucial Ecological Role Plants help create and maintain soil Dead plant material is decomposed by fungi, prokaryotes, and other decomposers Decomposed plant tissue becomes part of the soil, making it more fertile Roots of living plants help hold soil together, preventing erosion by wind and water

Plants help create and maintain soil

Dead plant material is decomposed by fungi, prokaryotes, and other decomposers

Decomposed plant tissue becomes part of the soil, making it more fertile

Roots of living plants help hold soil together, preventing erosion by wind and water

Human Necessities and Luxuries Plants provide shelter Wood is used to construct housing Plants provide fuel Wood: important fuel for warming and cooking in many parts of the world Coal: derived from the remains of ancient plants that have been transformed by geological processes

Plants provide shelter

Wood is used to construct housing

Plants provide fuel

Wood: important fuel for warming and cooking in many parts of the world

Coal: derived from the remains of ancient plants that have been transformed by geological processes

Human Necessities and Luxuries Plants provide medicine Many medicines and drugs were originally found in and extracted from plants, e.g. aspirin, Taxol, morphine Plants provide pleasure Flowers, gardens, and lawns Coffee, tea, and wine

Plants provide medicine

Many medicines and drugs were originally found in and extracted from plants, e.g. aspirin, Taxol, morphine

Plants provide pleasure

Flowers, gardens, and lawns

Coffee, tea, and wine

The End

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