7th Grade Chapter 2 Lesson 2

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7th Grade Chapter 2 Lesson 2

  1. 1. Chapter 2 Lesson 2 Pgs. 35-39 For Student Use Only
  2. 2. Pollen to Seed <ul><li>Seeds </li></ul><ul><ul><li>Pollination- the transfer of pollen from the anther to the stigma </li></ul></ul><ul><ul><li>Fertilization- the formation of a seed by uniting of a sperm nucleus from a pollen grain with an egg cell. </li></ul></ul>
  3. 3. Pollen to Seed <ul><li>Pollination: </li></ul><ul><ul><li>Anther opens and releases mature pollen </li></ul></ul><ul><ul><ul><li>Wind can carry the pollen </li></ul></ul></ul><ul><ul><ul><li>Insects, birds, or bats can carry pollen </li></ul></ul></ul><ul><ul><li>Pollinators are drawn to the plant by the nectar or petal color. </li></ul></ul><ul><ul><ul><li>Nectar- sweet liquid produces by flowers and stored at the base of the blossom. </li></ul></ul></ul>
  4. 4. Pollen to Seed <ul><li>Plants were created with some interesting provisions. </li></ul><ul><ul><li>Alfalfa- only releases pollen when disturbed by an insect. </li></ul></ul><ul><ul><li>Can release so much pollen that self-pollination occurs. </li></ul></ul><ul><ul><ul><li>Self-pollination: plant fertilizes egg with own pollen </li></ul></ul></ul>
  5. 5. Pollen to Seed <ul><li>Pollination: </li></ul><ul><ul><li>Cross-pollination- Pollen is carried from one plant to another by wind, insects, or animals. </li></ul></ul>
  6. 6. Pollen to Seed <ul><li>Post-Pollination: </li></ul><ul><ul><li>Pollen tube grows around the pollen on the stigma </li></ul></ul><ul><ul><li>The sperm nucleus divide to form 2 sperm nuclei </li></ul></ul><ul><ul><li>The sperm then slides through the pollen tube and unites with the egg cell. </li></ul></ul>
  7. 7. Pollen to Seed <ul><li>Post-Pollination: </li></ul><ul><ul><li>The joining of sperm and egg is called FERTILIZATION. </li></ul></ul><ul><ul><li>The fertilized egg (embryo) then begins to form the seed. </li></ul></ul><ul><ul><ul><li>Pollination only occurs in same type of plant. Grass cannot pollinate a dandelion. </li></ul></ul></ul>
  8. 8. Pollen to Seed <ul><li>Seed Development: </li></ul><ul><ul><li>A seed has three parts: </li></ul></ul><ul><ul><ul><li>Embryo- new plant </li></ul></ul></ul><ul><ul><ul><li>Endosperm- stored food </li></ul></ul></ul><ul><ul><ul><li>Seed Coat- outside covering </li></ul></ul></ul>
  9. 9. Pollen to Seed <ul><li>Embryo- </li></ul><ul><ul><li>Plumule- a tiny shoot that will become the leaves and stem </li></ul></ul><ul><ul><li>Radicle- a small root for the growing plant </li></ul></ul><ul><ul><li>Cotyledons- Structures used for absorbing and storing food </li></ul></ul>
  10. 10. Pollen to Seed <ul><li>Seed </li></ul><ul><ul><li>Food is first absorbed from the endosperm. </li></ul></ul><ul><ul><li>Seed coat- the tough outer coat </li></ul></ul><ul><ul><li>Germination- the early growth of the seed </li></ul></ul>
  11. 11. Pollen to Seed <ul><li>Fruits: </li></ul><ul><ul><li>Fruit: Anything that forms from the ovaries of a flower </li></ul></ul><ul><ul><li>Fruits aide with protecting the seed and with seed dispersal </li></ul></ul>
  12. 12. Pollen to Seed <ul><li>Seed Dispersal: </li></ul><ul><ul><li>Two kinds of Dispersal: </li></ul></ul><ul><ul><ul><li>Mechanical Dispersal: fruit explodes and scatters seeds </li></ul></ul></ul><ul><ul><ul><li>Agent Dispersal: Fruit is eaten or carried away and seeds are dispersed by other organisms or the wind. </li></ul></ul></ul><ul><ul><ul><ul><li>EX. Squirrels, Helicopters, or deer </li></ul></ul></ul></ul>

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