Plants Reproduction Part 1 lecture 15 Bryophytes Pteridophytes

Plants! Reproduction Part 1 (lecture 15) (Bryophytes & Pteridophytes)

Vegetative Reproduction § Asexual Reproduction involving parts of a plant § Cuttings § Plant develops from stem, root, or leaf fragments § Layering § Formation of root off of a stem § Grafting § Aligning vascular cambium of 2 or more plant parts to join them into one § Tissue Culture § Plant tissue cultivated and grown on nutrient media

Vegetative Reproduction African Violet leaf cutting Layering (raspberries) Grafted Tree V-graft (2 apple varieties) Plant tissue culture

Animal vs. Plant Life Cycle Animal Plant diploid multicellular individual 2 n mitosis diploid multicellular sporophyte mitosis 2 n meiosis zygote 2 n fertilization haploid unicellular gametes 1 n no multicellular haploid zygote 2 n fertilization meiosis gametes 1 n spores 1 n mitosis haploid multicellular gametophyte 1 n alternation of generations

Alternation of Generations § Alternation of Generations – A life cycle that includes a multicellular diploid form (sporophyte) and a multicellular haploid form (gametophyte) § Gametophyte - multicellular haploid form that mitotically produces haploid gametes that unite and grow into the sporophyte generation § Sporophyte - multicellular diploid form that results from a union of gametes and that meiotically produces haploid spores that grow into the gametophyte generation

Alternation of Generations

WHY, OH WHY ? (does bio have to be so freaking confusing!) § A “best of both worlds” idea § Spore – with spores, only one parent contributes to the genes in the offspring § Beneficial if the parent is in a stable environment because offspring will have all of the genes that are successful in that area § Gametes – both parents contribute genes § Beneficial in a changing environment where different traits may enhance survival of offspring

First Land Plants haploid § Bryophytes: mosses & liverworts § non-vascular § no water transport system § no true roots § swimming sperm § flagellated sperm § lifecycle dominated by haploid gametophyte stage § fuzzy moss plant you are familiar with is haploid § spores for reproduction § haploid cells which sprout to form gametophyte diploid

Bryophyte Reproduction § Gametangia (on gametophyte) produce haploid gametes § Antheridium – produces sperm § Archegonium – produces egg § Resulting zygote grows into a diploid structure (sporophyte) § In mosses the sporophyte is a stalk § Spores from sporophyte disperse & develop into haploid gametes Gametophyte Dominant!

First Vascular Plants § Pteridophytes: ferns § vascular § water transport system § xylem, phloem, roots, leaves § swimming sperm § flagellated sperm § life cycle dominated by sporophyte stage § leafy fern plant you are familiar with is diploid § fragile independent gametophyte (prothallus) § spores for reproduction § haploid cells which sprout to form gametophyte haploid diploid

Pteridophyte Reproduction § Produce spores that form gametophytes § Sori – sporangia clusters on the underside of fern fronds § Meiosis in sporangia forms spores § Antheridia produce sperm and archegonia produce eggs § Sperm swim to meet eggs (fertilization occurs at female reproductive structure) & diploid sporophyte results Sporophyte Dominant!

Alternation of Generations § Fern gametophyte (1 n) § small haploid plant which produces gametes § homospory: male & female on same plant archegonia antheridia

Fern Reproduction haploid

Alternation of Generations diploid produces male & female gametes archegonia antheridia haploid

Pop Quiz! 1. The evolution of plants: • a. started in aquatic environments. • b. was marked by the development of specialized tissues such as vascular tissue. • c. led to the development of specialized organs. • d. demonstrated a trend toward radiating into drier environments. • e. all of these

Pop Quiz! 2. All but which of the following would be associated with vascular plants? § a. root systems § b. Bryophytes § c. Angiosperms § d. Gymnosperms § e. shoot systems 3. Ferns are more advanced than mosses because mosses lack which structure found in ferns? § a. spores § b. cuticle § c. xylem § d. sporophytes § e. pollen