Compare & Contrast Life Cycle of Plants
Similarities
- All follow the Alternation of Generations
- All have 1N and 2N
- All have gametophyte and sporophyte stages
- All have mitosis and meiosis
- Bryophyte & Pteridophyte: sporangium undergoes meiosis to create spores and releases the spores, water transfers sperm to egg, grow non-true roots
- Gymnosperm & Angiosperm: pollen grains are carried to the female gametophyte via wind, seeds both have nutrient reserves, seeds grow into mature sporophytes, pollen grains are made from meiosis, germination - pollen tube grows from pollen grain to reach the archegonium
- Pteridophyte & Gymnosperms & Angiosperms: male and female gametophytes are located on the same plant (monoecious)
Life Cycle of Bryophytes, Pteridophyes, Gymnosperm & Angiosperm
Bryophytes
- Operculum comes off the sporangium, releasing the spores
- Spores grow through mitosis
- 2 separate plants for male and female parts (antheridium & archegonium)
- Water carries sperm from the archegonium to the antheridium, where the ovum is fertilized.
- Fertilized ovum grows inside the archegonium into an embryo, then a mature sporophyte
- Sporangium undergoes meiosis, creating haploid spores
Pteridophyte
- Archegonium and antheridium are both located on the prothallus
- Water carries sperm from the antheridium to the archegonium
- Ovum is fertilized by the sperm and grows by mitosis into embryo
- Embryo grows into a fiddlehead (sporophyte), and continues to grow by mitosis into a mature sporophyte
- Sporangium on sporophyte undergoes meiosis, producing haploid spores, which grow by mitosis into a gametophyte (prothallus)
Gymnosperms
- seeds undergo mitosis, growing into a seedling
- the seedling continues to grow into a mature sporophyte
- microsporangia on male cone undergoes meiosis producing pollen grains
- megaspore mother cell undergoes meiosis producing four daughter cells
- pollen grains are carried from from the male cone to the female cone via wind
- Pollination occurs in ovum & germination begins
- surviving cell grows into a megagametophyte inside the megaspore, which contain 2-3 archegonium.
- pollen tube grows and attaches to one of the archegonium, where the sperm nucleus and egg nucleus fuse - fertilization occurs
- The zygote grows into an embryo(2N) which is surrounded by nutrients (1N) and by the seed coat (2N)
- The embryo grows through mitosis into a seed
Angiosperm
- The anther on the stamen produces pollen grains which get transported via wind onto the stigma
- The pollen grain grows a pollen tube down the style to the ovary where it fertilized the ovum
- The zygote grows via mitosis into an embryo, which then grows fruit around it
- The seed continues to grow roots, and into a seedling that eventually grows into a mature sporophyte