1. AP Biology 2005-2006 Angiosperm life cycle female gametophyte in ovary male gametophyte in pollen sporophyte in seed fertilization Polar nuclei Egg cell Pollen grains

2. AP Biology 2005-2006 Double Fertilization Ovule Pollination Sperm cells Pollen tube Pollen grain Zygote (2n) Polar nuclei Egg cell Endosperm (3n)  food in seed  coconut milk  grains What’s the adaptive advantage?

3. AP Biology 2005-2006 Plant embryo endosperm cotyledons embryo seed coat ovary wall

4. AP Biology 2005-2006 Angiosperm: fruiting plants

5. AP Biology 2005-2006 Fruit development  Peach, plum, apricot, cherry  1 flower : 1 carpel : 1 ovary : 1 seed

6. AP Biology 2005-2006 Fruit development  Apple, pear  1 flower : 5 carpels : many ovaries : many seeds

7. AP Biology 2005-2006 Fruit development  Citrus fruit  1 flower : many carpels : many ovaries : many seeds

8. AP Biology 2005-2006 Fruit development  Raspberry, strawberry  1 flower : many ovaries : many seeds

9. AP Biology 2005-2006 Other fruits…

10. AP Biology 2005-2006 Seed dispersal  Plants produce enormous numbers of seeds to compensate for low survival rate  vast amount of genetic variation for natural selection to screen

11. AP Biology 2005-2006 Plant Response  Stimuli & a Stationary Life  animals respond to stimuli by changing behavior  move toward positive stimuli  move away from negative stimuli  plants respond to stimuli by adjusting growth & development

12. AP Biology 2005-2006 Signal Transduction Pathway model  signal triggers receptor  receptor triggers internal cellular messengers & then cellular response  receptor  signal pathway (2° messengers)  response What kinds of molecules are the receptors?

13. AP Biology 2005-2006 Signal Transduction Pathway example 1. Light signal is detected by the phytochrome receptor, which then activates at least 2 signal transduction pathways 2. One pathway uses cGMP as a 2nd messenger to activate a protein kinase. The other pathway involves increases in cytoplasmic Ca 2+ that activates a different protein kinase. 3. Both pathways lead to expression of genes for proteins that function in greening response of plant.

14. AP Biology 2005-2006 Plant hormones  Chemical signals that coordinate different parts of an organism  only tiny amounts are required  produced by 1 part of body  transported to another part  binds to specific receptor  triggers response in target cells & tissues

15. AP Biology 2005-2006 Plant hormones  auxins  gibberellins  abscisic acid  ethylene  cytokinins  brassicosteroids