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Origin of flower
- -where all and parts are present
- -how many of each part
- - Parts separate or unitep
- 1. Mitosis in megaspore 2. Pollen tube grows -->
- 1. Cell wall form 2.) More pollen tub, growth sperm formed -->
- 1.) Pollen tube enter megametophyte. 2.) Sperm released (sperm x egg --> zygote, sperm x polar nuclei --> endosperm cell)-->
- 1.) Zygote develop into embryo. 2.) Endosperm cell develop into endosperm tissue. 3.) Ingument and nucellus become seed coat. 4.) Ovary wall develops into pericap
Solution to gymo shortcomings
- A.) Pollen transport
- B.) Pollen selectivity
- C.) Seed dispersal
- Solutions: Petals
- Animals transport pollen
- 1.) Get animal to flowers
- a.)Rewards -What animals needs or wants.
- food- nectar and pollen
- Reproduction (sex and place to raise young in)
- b.) Advertisment: Petals (sight [color, shape,size] and smell [osmophores]
- 2.) Ensure that animal touches anthers and stigma.
Solution: Enclosing ovules in carpel
- 1.) Pollen can only stick to stigma
- 2.) Must grow a long pollen tube to get to egg.
- 3.) Carpel interacts chemically with pollen and pollen tube
- a.) Stigma and pollen- protein interaction.
- -Favorable: Pollen tube allowed to grow.
- -Unfavorable: Not allowed to grow.
- b.) Carpel tissue and pollen tube- protein interaction
- -Favorable: Allows continued growth.
- - Unfavorable: Pollen tube killed by carpel with RNAase.
- Too large and heavy to disperse far by wind.
- Solution: Enclosing ovules in carpels.
- 1.) Ovule in carpel develops into seed in a pericap.
- 2.) Pericap can specialize in dispersal. Many modification possible.
- a.) Animal food
- - seed stick to them or be partly digested or be completely digested
- b.) Stick to animal fur.
- c.) More effective and dispersal.
- d.) Water