24.2 Seed Development and Germination

1. 24.2 Seed Development and Germination

2. Seed Dispersal Dispersal by Animal Seeds contained in a juicy, nutritious fruit Fruit feeds the animal, not the seed The seed coat protects the embryo from digestive juices. Seed sprouts in animal feces

3. Seed Dispersal Dispersal by Wind Short and long distance dispersal Seed rely on chance to find a favorable site Usually many seeds released Ex: tumbleweeds, maple, dandelions

4. Seed Dispersal Dispersal by Water Seeds are lightweight to float on water Example: Coconut Trees grow in coastal tropical areas Has a liquid endosperm Can float for many weeks on the ocean and reach remote islands

5. Read page 97 in the Botany Coloring Book and Answer the Questions. Explain expulsion as a means of seed dispersal. Describe one advantage and one disadvantage. How does the tumbleweed use wind to distribute seeds? Name 2 plants that rely on water for dispersal. Explain how animals are able to transport seeds externally and internally.

6. Seed Dormancy Dormancy – the period of time when the seed is alive but not growing. Allows seeds to germinate under ideal conditions. What factors end seed dormancy? Temperature Moisture Sunlight

7. Seed Germination Def – the early growth stage of a plant embryo The process Seed absorbs water, endosperm swells and cracks seed coat – IMBIBITION. Young root begins to grow down Shoot begins to grow up

8. 24-3 Plant Propagation and Agriculture

9. Vegetative Reproduction Asexual Reproduction Making new plants from stems, plantlets, and roots Ex: Spiders plants – plantlets Ex: Strawberries – Stolons – horizontal stems that can take root.

10. Plant Propagation Making many copies of a plant Producing offspring from seedless plants Cutting: cut a length of stem and plant in in soil, or use special rooting hormones.

11. Plant Propagation 2. Grafting & Budding: new plants are grown on plants with strong root systems

12. Agriculture “The systematic cultivation of plants” Before 10,000 BC – Humans survived as hunters and gathers. 10,000 BC – Farming Practices began in the Fertile Crescent (Middle East) Kept people in one place Establish towns and cities

13. Agriculture Most people in the world depend on a few crops We mostly rely on the endosperm

14. Changes in Agriculture Selective Breeding – only allowing organisms with certain traits to reproduce. Ex: teosinte – maize - corn Ex: cabbage – broccoli – Brussels sprouts

15. Change in Agriculture Genetically Modified Crops – genes are inserted to improve crop yield. Ex – Round-up resistance, pest resistance, and high yield genes. Advantages? Disadvantages? Commercial Agriculture – replaces small, family owned farms Mass crop production Unsustainable methods Ex. Synthetic Fertilizer

16. Earth-Friendly Agricultural Polyculture – planting multiple crops in a single field. Terrace farming – minimizes soil run-off along hills No – Till Farming – place seeds directly into the ground, reduces soil erosion.

17. GM Crop Controversy Discussion Questions Knowing that you will eat GM crops for the majority of your life and the long term effects of the crops have not tested, how do you feel about being “guinea pigs” for theses crops? Are we “playing god” by genetically engineering crops? Can we (or should we) rely on GM crops to feed our growing population and end world hunger? Percy or Monsanto? Why?