PLANTS EVERYTHING YOU NEVER WANTED TO KNOW BUT NEEDED TO FOR THE AP EXAM

Kingdom: Plants Domain Eukarya 2007-2008 Domain Bacteria Archaea Common ancestor 2007-2008

Land plants evolved from green algae Researchers have identified green algae called charophyceans as the closest relatives of land plants

Genetic Evidence Comparisons of both nuclear and chloroplast genes Point to charophyceans as the closest living relatives of land plants Chara, a pond organism (a) 10 mm Coleochaete orbicularis, a disk- shaped charophycean (LM) (b) 40 µm Figure 29.3a, b

Animal vs. Plant life cycle diploid multicellular individual 2n diploid multicellular sporophyte 2n mitosis zygote 2n mitosis meiosis fertilization meiosis gametes 1n spores 1n zygote 2n fertilization mitosis mitosis haploid unicellular gametes 1n haploid multicellular gametophyte 1n no multicellular haploid alternation of generations

Pollen Pollen eliminated the requirement for water for fertilization spread through wind & animal

Angiosperm: flowering plants

Flower Modified shoot with 4 rings of modified leaves sepals petals stamens male carpel female Anther Filament Stamen Stigma Style Ovary Carpel Sepal Petal Ovule sepals petals stamens carpel adaptations through mutations

The life cycle of an angiosperm Key Mature flower on sporophyte plant (2n) Ovule with megasporangium (2n) Female gametophyte (embryo sac) Nucleus of developing endosperm (3n) Discharged sperm nuclei (n) Pollen tube Male gametophyte (in pollen grain) Sperm Surviving megaspore (n) Microspore (n) Generative cell Tube cell Stigma Ovary MEIOSIS Megasporangium grains Egg Nucleus (n) Zygote (2n) Antipodal cells Polar nuclei Synergids Egg (n) Embryo (2n) Endosperm (food Supply) (3n) Seed coat (2n) Seed FERTILIZATION Haploid (n) Diploid (2n) Anther Style Microsporangium Microsporocytes (2n) Germinating Anthers contain microsporangia. Each microsporangium contains micro- sporocytes (microspore mother cells) that divide by meiosis, producing microspores. 1 Microspores form pollen grains (containing male gametophytes). The generative cell will divide to form two sperm. The tube cell will produce the pollen tube. 2 When a seed germinates, the embryo develops into a mature sporophyte. 7 In the megasporangium of each ovule, the megasporocyte divides by meiosis and produces four megaspores. The surviving megaspore in each ovule forms a female gametophyte (embryo sac). 3 The zygote develops into an embryo that is packaged along with food into a seed. (The fruit tissues surround- ing the seed are not shown). 6 After pollina- tion, eventually two sperm nuclei are discharged in each ovule. 4 Double fertilization occurs. One sperm fertilizes the egg, forming a zygote. The other sperm combines with the two polar nuclei to form the nucleus of the endosperm, which is triploid in this example. 5 Figure 30.10

From Ovary to Fruit A fruit Develops from the ovary Protects the enclosed seeds Aids in the dispersal of seeds by wind or animals

Co-evolution: flowers & pollinators

Plant Structure, Growth, and Development

An example of signal transduction in plants 1 Reception   2 Transduction 3 Response CYTOPLASM Plasma membrane Phytochrome activated by light Cell wall Light cGMP Second messenger produced Specific protein kinase 1 Transcription factor 1 NUCLEUS P Translation De-etiolation (greening) response proteins Ca2+ Ca2+ channel opened kinase 2 factor 2 2 One pathway uses cGMP as a second messenger that activates a specific protein kinase.The other pathway involves an increase in cytoplasmic Ca2+ that activates another specific protein kinase. 3 Both pathways lead to expression of genes for proteins that function in the de-etiolation (greening) response. 1 The light signal is detected by the phytochrome receptor, which then activates at least two signal transduction pathways. Figure 39.4

The bending of a grass seedling toward light Begins with the plant sensing the direction, quantity, and color of the light Figure 39.1

Xylem Conducts most of the water and minerals Includes dead cells called tracheids Phloem Distributes sugars, amino acids, and other organic products Consists of living cells