Transcript plant_reproduction

Plant Reproduction
Asexual Reproduction
• Asexual reproduction is natural “cloning.”
Parts of the plant, such as leaves or
stems, and roots are produced by
mitosis.
Sexual Reproduction
• Sexual reproduction requires fusion of
male sex cells in the pollen grain with
female sex cells in the ovule.
Terms to recall:
• Haploid: having a single set of
chromosomes in each cell.
• Diploid: having two sets of chromosomes
in each cell.
• Mitosis: cell division, which produces two
genetically identical cells.
• Meiosis: reduction division, which
produces four haploid reproductive cells.
The Plant Life Cycle
Alternation of Generations
• Plants have a double life cycle with two
distinct forms:
1. Sporophyte: (growth of the plant
phase) is diploid, produces haploid
spores by meiosis.
2. Gametophyte: (development and
release of sex cells) is haploid,
produces gametes by mitosis.
Non-flowering plants
(Gymnosperms)
Mosses, ferns and related plants have motile,
swimming sperm.
Reproduction in these plants requires wet
conditions, and also requires having male and
female parts close together.
Moss Life Cycle
Fern Life Cycle
Conifers
Conifers (also considered non-flowering
plants) have reduced gametophytes.
• Male gametophyte is contained in a dry
pollen grain.
• Female gametophyte is a few cells
inside of the structures that become
the seed.
Conifer life cycle
Conifer pollination
• Conifers are wind-pollinated plants.
• Chance allows some pollen to land on
the scales of female cones.
• Pollen germinates, grows a pollen tube
into the egg to allow sperm to fertilize the
egg.
Pollen Dispersal Strategies
Showy flowers are the result of selection for
more efficient pollination strategies.
Flower parts are modified leaves. Those that
were brightly colored attracted insects in search
of pollen.
• Why would insects search for pollen? What
rewards do flowers offer?
• What are advantages and disadvantages to
relying on insects as pollinators?
Flowering Plants
(Angiosperms)
Flower Parts
Incomplete flowers
Flowers are complete if they have all parts, and
perfect if they have both male and female parts.
Examples:
• Grass flowers: incomplete, usually imperfect
(separate male and female flowers)
• A tulip is complete and perfect.
Imperfect flowers
Angiosperm Life Cycle
Flower to Fruit