BI111 Lecture Notes - Lecture 11: Coevolution, Beakhead, Phloem
BI111 – L11
Phylogeny, Plants, and Plant Body’s
Challenge 3: Aridity and Reproduction
The gametophytes of bryophytes, ferns, and some gymnosperms produce motile (haploid) sperm
cells (like their algal ancestors)
Impossible for sperm to reach eggs in absence of water
Solution:
The “seed plants”
Gymnosperms and angiosperms
Gymnosperms:
“Naked” seed plants
oSporophyte’s haploid spores retained in reproductive structures
Pollen grains produce nonmotile sperm
oMale gametophyte contained within protective covering, eliminating the liquid-water
requirement for fertilization
oPollination - transfer of pollen to female reproductive parts
oPrimarily wind and water based in gymnosperms
Ovule:
oSporophyte structure produces female gametophyte with egg
oConnected to sporophyte by protective tissue
Seeds:
oStructure forms when ovule matures after sperm fertilization through pollination
Embryo sporophyte (diploid)
Surrounded by nutritive tissues
Protective coat
oSeeds are major adaptations for uncertain environments
Long distance transport
Potential dormancy
Angiosperms:
Flowering plants with covered seeds
oFlowers contain carpels at their center that protects ovules and seeds
oFruit structure nourishes and disperses seeds
oDouble fertilization
Produces embryo and endosperm
2 major groups:
oMonocots (single cotyledon):
Grasses, palms, lilies, orchids, and others
Parallel-veined leaves common
Bundles of vascular tissue scattered in stem
oEudicots (2 cotyledons):
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Document Summary
The gametophytes of bryophytes, ferns, and some gymnosperms produce motile (haploid) sperm cells (like their algal ancestors) Impossible for sperm to reach eggs in absence of water. Naked seed plants: sporophyte"s haploid spores retained in reproductive structures. Pollen grains produce nonmotile sperm: male gametophyte contained within protective covering, eliminating the liquid-water requirement for fertilization, pollination - transfer of pollen to female reproductive parts, primarily wind and water based in gymnosperms. Ovule: sporophyte structure produces female gametophyte with egg, connected to sporophyte by protective tissue. Seeds: structure forms when ovule matures after sperm fertilization through pollination. Protective coat: seeds are major adaptations for uncertain environments. Flowering plants with covered seeds: flowers contain carpels at their center that protects ovules and seeds, fruit structure nourishes and disperses seeds, double fertilization. Bundles of vascular tissue scattered in stem: eudicots (2 cotyledons): Most fruit trees, roses, beans, potatoes, and others. Central core of vascular tissue in stem.