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

AP Biology 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?

AP Biology Plant embryo endosperm cotyledons embryo seed coat ovary wall

AP Biology Angiosperm: fruiting plants

AP Biology Fruit development  Peach, plum, apricot, cherry  1 flower : 1 carpel : 1 ovary : 1 seed

AP Biology Fruit development  Apple, pear  1 flower : 5 carpels : many ovaries : many seeds

AP Biology Fruit development  Citrus fruit  1 flower : many carpels : many ovaries : many seeds

AP Biology Fruit development  Raspberry, strawberry  1 flower : many ovaries : many seeds

AP Biology Other fruits…

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

AP Biology 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

AP Biology 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?

AP Biology 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.

AP Biology 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

AP Biology Plant hormones  auxins  gibberellins  abscisic acid  ethylene  cytokinins  brassicosteroids