Bio Lab

• 1. Multicellular
• 2. Photosynthetic (chloroplasts)
• 3. Cellulose in cell walls
• 4. Starch as a storage polysacharide
• 5. Alternation of generations
• 6. Heterogamy with gametes produced in gametangia

• Bryophytes:
• Phylum Bryophyta - mosses
• Phylum Hepatophyta - liverworts

• Seedless plants:
• Phylum Lycophyta - club mosses
• Phylum Pterophyta - ferns, horsetails, whisk ferns

• Alternation of generations: plants alternate between haploid gametophyte generation and a diploid sporophyte generation.
• Diploid sporophyte generation is the dominant generation in all plants except bryophytes.
• Cycle:
• 1. The gametophyte produces gametes inside a jacket of cells forming gametangia.
• 2. Eggs are produced by mitosis in archegonia and sperm are produced in antheridia.
• 3. The gametes fuse by entrance of the sperm into the archegonium, forming a diploid zygote, the first stage of the diploid sporophyte generation.

Plant life cycle produces gametes by mitosis; spores are produced by meiosis.

• No vascular tissue (mass).
• No true roots, stems, leaves.
• Sperm swims to egg so water is required for sexual reproduction.
• Gametophyte generation predominates.
• Sporophyte dependent on gametophyte.
• Homospory, one type of spore (all identical).
• Dispersal by spores.

• Vascular tissue (xylem, phloem).
• Roots, stem, leaves.
• Water not required for sexual reproduction (sperm nuclei inside pollen grain).
• Sporophyte generation predominates.
• Gametophyte reduced and dependent on sporophyte.
• Heterospory, two kinds of spore (micro [male] and mega [female] spores).
• Dispersal by seeds.

• Spore:
• A haploid (n) cell inside a dessication resistant coat.
• Germinates to give rise to a multicellular haploid plant-gametophyte.

• Seed:
• A diploid sporophyte embryo plus nutritive material inside a dessication resistant seed coat.
• Germinates to give rise to a multicellular mature diploid plant (sporophyte).

• Gametophyte is the dominant generation.
• Restricted to moist habitats for their reproductive cycle.
• Remains close to ground enabling the motile sperm to swim from the antheridium to the archegonium and fertilize egg.
• Have a cuticle but lack stomata on the surface of the gametophyte thallus (plant body).
• Stomata is present on the sporophyte in some.

• Steps of fertilization:
• Sperm swim through a film of water to the archegonium and swim down the neck of the egg.
• The diploid zygote divides by mitosis and develops into an embryonic sporophyte within the archegonium.
• Spores develop by meiosis in the sporangium at the end of the sporophyte. The spores are discharged and in a favolable environment develop into new gametophytes.

• Liverworts have a flat thallus.
• Rhizoids; rootlike extensions on the lower surface, that primarily anchor plants.
• Pores; openings that function in gas exchange.
• Gemmae cups; contain flat disks of green tissue called gemmae.
• Gemmae are washed out of the cups when it rains, and they grow into new, genetically identical liverworts.

• Ancestral:
• Mobile sperm (require water).
• No vascular tissue.
• No roots, stems, leaves.
• Gametophyte dominant.
• Sporophyte depends on gametophyte.

• Derived:
• Cuticle.
• Gameotangia and sporangia.
• Rhizoids.
• Stomata on moss.
• Sporophyte.

• All have vascular tissue, which is specialized for conducting water, nutrients, and photosynthetic products.
• Sporophyte is the dominant generation.
• Gametophyte usually independent of sporophyte.
• Have well developed leaves, roots, stomata and structural support tissue.
• Retain ancestral feature of motile sperm that require water for fertilization, the gametophyte is small and restricted to moist habitats.
• Lycophyta (club mosses, spike mosses, quillworts) and Pterophyta (ferns, horsetails, whisk ferns).

• Usually in moist habitats except Selaginella, the resurrection plant, that inhabits deserts.
• Nonvascular plants and most seedless vascular plants produce one type of spore (homospory).
• Produce two kinds of spores (heterospory), unusual.
• Megaspores; large spores divide by mitosis to produce female gametophyte.
• Microspores; numerous small spores that produce male gametophyte by mitosis.

Psilophytes (whisk ferns) are diminutive, dichotomously branched (Y branches), photosynthetic stems that reproduce sexually by aerial spores.

• Sphenophytes (horsetails) have green jointed stems with occasional clusters of leaves or branches. Their cell walls contain silica that give the stem a rough texture.
• Contain strobili which are clusters of sporangia that produce spores.

• Ferns are the most succesfull occupying deserts to tropical rain forests. They have rhizoids to anchor the plant.
• Contain sori which are clusters of sporangia and leaves called sporophylls.

• The haploid spores of ferns fall to the ground and grow into heart-shaped, gametophyte plants.
• All seedless plants depend on an external source of water for a sperm to swim to an egg to effect fertilization and for growth of the resulting sporophyte plant.
• Eggs cells are produced by mitosis in urnlike structures callend archegonia, and sperm cells are produced by mitosis in globular structures callend artheridia.

• Ancestral:
• Sperm requires water for fertilization.
• Reduce gametophyte but usually independent.
• Homospory.

• Derived:
• Vascular Tissue.
• Independent sporophyte.
• Complex stomata.
• Strobili.
• Waxy cuticle.
• Heterospory.

• Gametangium: protects production of gamtes from drying out.
• Cuticle: prevents dessication of plant body.
• Rhizoid: anchors plant to the ground.
• Motile sperm: liability of land because water is needed for reproduction.
• Vascular tissue: transport and support.
• Gemma cups: production of new haploid plants by asexual reproduction.

Nonvascular: gametophyte dominate

Seedless: sporophyte dominate

• Antheridium: produce and protect sperm. In gametophyte. Eg. fern, liverwort, mosses.
• Archegonium: produce and protect eggs. In gametophyte. Eg. fern, liverwort, mosses.
• Spore: dispersal. In gametophyte. Eg. fern, liverwort, mosses.
• Gamete: fuse to restore diploid number of chromosomes. In gametophyte. Eg. fern, liverwort, mosses.
• Rhizome: underground stem to anchor the plant. In sporophyte. Only in fern.
• Gemma: asexual reproduction. In gametophyte. Only in liverwort.
• Sporangium: protects spores, site of meiosis. In sporophyte. Eg. moss, fern.
• Strobilus: enhance for dispersal. In sporophyte. Eg. club moss.
• Sorus: enhance for dispersal. In sporophyte. Only in fern.