Plant Biology Exam 4 Review

Seedless Vascular Plants

Reproduce by forming spores and have the differentiation of stems, leaves, and roots

Include lycophytes and pterophytes

Leaf Types

Microphyll and megaphyll

Microphyll

Has a single vein and probably evolved as a stem outgrowth

Present in lycophytes

Megaphyll

Has a branched system of veins and probably evolved by fusion of stem branches

Present in pterophytes and seed plants

Fern Life Cycle

Dominant sporophyte generation

Water required for sexual reproduction

Fern Sporophyte

Perennial rhizome (root) and fronds (leaves)

Sporangia develop on underside of fronds in clusters (sori)

Fern Gametophyte

Prothallus: Green heart-shaped structure that produces female and male structures

Antheridia on rhizoids and archegonia on central prothallus

Free-living

Fern Sporangia

Can be born on different stalks

Annulus (unevenly thickened walls) breaks open and sporangia seeds are dispersed

Whisk Ferns

Contain only stem that have rhizomes and aerial stems that perform photosynthesis

Sporangia form on aerial stems and produce haploid spores by meiosis

Horsetails

Have true stems, leaves, and roots

Common in wet habitats

Water required for fertilization

Dominant saprophyte + free-living gametophyte

Horsetail Structures

Stems have rhizomes + aerial stems that are hollow with silico and perform photosynthesis

Sporangia are located around an axis

Small leaves are fused together in whorls at nodes

Club mosses

Have trues roots, rhizomes, short aerial stems, and leaves

Similar life cycle to ferns

Sporangia form one strobilus at aerial stem tips

Spike Mosses

Found in moist tropics / subtropics with diverse growth forms

Creeping, branched roots have rhizomes and steps (4 rows of microphyll)

Spike mosses, quillworts, and some ferns are _____

Heterosporous

Heterospory

Two types of spores (microspores and megaspores)

Microspore

Produce male gametophytes

Megaspore

Produce female gametophyte

Heterospory Structure

Microsporangium and megasporangium in strobilus

Homospory

One type of spore produced by meiosis

(Bryophytes + some seedless vascular plants)

Quillwort

Freshwater perennials

Swollen underground stem (corm) that produces quill leaves

No aerial stems

Seeds

Consist of embryo, endosperm, and seed coat

Productively superior to spores

Contains a young multicellular plant with an abundant food supply protected by a seed coat

Gymnosperm + Angiosperm Similarities

Bear seeds

Vascular tissue

Alternative generations (dominant sporophyte and dependent gametophyte)

Gymnosperms

Naked seeds

Among the tallest and oldest trees

Subgroups (phyla): Conifer, cycad, ginkgo, and gnetophytes)

Conifers

Woody species often producing resin, typically evergreen or deciduous with megaphyll needle-like leaves

What is the function of resin?

Protect against insects and fungal attacks

Conifer Life Cycle (Pine)

Dominant sporophyte, heterosporous, microspores + megaspores

Conifer Male Cone

Microporangia forms under sporophyll (leaflike scales)

Microspore mother in the microsporangium form haploid microspores by meiosis which develops into male gametophytes (pollen grains)

Pollen Grain

2 cells (generative + tube) when mature

2 air sacs for wind dissemination

Conifer Female Cone

Large, spiral cone scales

Ovule (megasporangia) on cone scale base with one megaspore

4 megaspore by meiosis - 1 undergoes lots of mitosis to form gametophyte which produces an archegonia

Conifer Fertilizations via Pollination

Pollen transferred from male to female cones

Produces embryo by sperm being sent to eggs for fertilization via pollen tubes

Seeds have 3 different sources

Integument —> seed coat (2n)

Embryo (2n) —> seed

Endosperm (n)

Is water required for conifer fertilization

No, which makes them able to live in diverse envrionments

Cycads

Located in tropics & subtropics

Stout trunk, large compound leaves

Cycad Reproduction

Dioecious with flagellated sperm cells (vestiges)

Pollen moved by the air / insects

Does not require water

Pollen tube for sperm

Dioecy

Female + male cones are on different plants

Ginkgo

Native to Eastern China

Deciduous

Important medicinal plant

Ginkgo Reproduction

Dioecious

Male pollen grains + flagellated sperm

Exposed ovules

Gnetophytes

Vessel elements

Cone clusters resemble flower clusters

Life cycle is similar to angiosperms

Angiosperms

Reproduce sexually by forming flowers + seeds in fruit

Diverse in appearance and habitat

Important to humans

__ and __ are the two major groups of angiosperms

Monocots, dicots

Monocots and dicots differ in __ and __

Cotyledon number, organ structure

Angiosperm Life Cycle

Angiosperm Ovule

Enclosed in integuments and has a micropyle (channel)

Produces embryo sac (female gametophyte) through mitosis of ¼ haploid megaspores from diploid mother megaspore

Angiosperm Female Gametophyte

Contains 2 synergids (n) and 1 egg cell (n) close to micropyle, 3 antipodal cells (n) and 1 central cell (2n-polar nuclei)

Angiosperm Male Gametophyte

Produced in anther that contains pollen sacs

Pollen grain (male gametophyte) and 2 tube cells (tube+generative) formed from mitosis of haploid microspores

Generative cell forms 2 sperm in pollen tube (male gametophyte)

Double Fertilization

Unique to angiosperms

Pollen germinate on stigma - pollen tube grows towards ovule

Two sperms fertilize inside embryo sac (3n fertilized central cell)

Angiosperm Seed + Fruit Development

Zygote —> embryo in seed

Fertilized central cell —> endosperm

Ovary —> fruit

Integument —> seed coat

Other cells disintegrate

Fruit Functional Role

Seed protection, seed dispersal

Apomixis

Production of seeds w/out fertilizations (asexual reproduction)

Embryos developed from ovule cell or central cells

(dandelions, blackberries)

Flower

Reproductive shoot

Morphological features increase likelihood of sexual reproduction

Floral pasts: sepal, petal, stamen, pistil

Angiosperm floral parts are arranged in ___

Whorls

Sepals

Outermost whorl

Lead-life and form calyx

Protect other floral parts

Petals

Whorl inside sepals

Form corolla

Large w/ bright colors to attract pollinators

Stamen

Inside petals

Contain filament + anther

Pollens produced on anther

Pistil

Formed from multiple carpel

Contains stigma, style, and ovary

Simple/compound pistil/ovary

Complete vs. Incomplete flower

Complete: Has the four floral parts

Incomplete: Lacks one or more floral parts

Perfect vs. Imperfect Flower

Perfect: Has both stamen and pistil

Imperfect: Lacks either stamen or pistil

Inflorescence

Group of flowers - several to hundreds well arranged

Head (sunflower), umbel (simple or compound), raceme, spike, panicle, or corymb

Regions of Mature Fruit

Exocarp: Skin part

Endocarp: Inner boundary w/ seeds

Mesocarp: Region between exocarp and endocarp

All make up the pericarp