Ch 38: Angiosperm reproduction - Define angiosperm Name the dominant generation What are the male gametophytes Where are female gametophytes produced?(embryo sacs)

angiosperm reproductive parts, process Anther Filament Stamen Pollen tube stigma Ovary (base of carpel) Ovule Embryo sac (n) (female gametophyte) FERTILIZATION Egg (n) Sperm (n) Petal Receptacle Sepal Style Ovary Mature sporophyte (2n) Zygote Embryo (2n) fruit Germinating Seed Carpel Stigma

Flower Structure Flowers Reproductive organs of the angiosperm sporophyte Composed of four floral parts: sepals, petals, stamens, and carpels The ABC genetic genes: 3, turned on in different combinations, produce the different parts of a flower.

REPRODUCTIVE VARIATIONS variations in floral structure Bilateral symmetry (orchid) Sepal Radial symmetry (daffodil) Inferior ovary Superior ovary inflorescence monoecious Dioecious REPRODUCTIVE VARIATIONS SYMMETRY OVARY LOCATION FLORAL DISTRIBUTION

A. anther; microsporangia. Cells 2n. B. Loculus (chamber) C A. anther; microsporangia . Cells 2n. B. Loculus (chamber) C. Tetrad stage, formed by meiosis I and II, begin to form n gametophyte. D. Mitotic division forms the microgametophyte or pollen. E. Ripening pollen grain: VN, = pollen tube nucleus,;GN (generative will divide into two sperm cells. F. Ripe pollen grain in outer cell wall, the exine. The grainy dark purple structure in the middle of the pollen grain is the vegetative nucleus. G. Diagram in 3 parts:

Development of a female gametophyte (embryo sac) Key to labels MITOSIS MEIOSIS Ovule Integuments Embryo sac Mega- sporangium Megasporocyte 2n Micropyle Antipodel Cells (3) Polar Nuclei (2) Egg (1) Synergids (2) multicellular f. Gametophyte by mitosis. The ovule = embryo sac + integuments from sporangium. 3 Female gametophyte (embryo sac) Diploid (2n) 2n 100 m 1 of the 4 cells from meiosis becomes the megaspore.

Mechanisms That Prevent Self-Fertilization ??? Can you recognize the problem??? Stigma Stigma Anther with pollen Pin flower Thrum flower

Plant pollination self-incompatibility Cell to cell recognition usually prevents pollen “germination” Similar to recognition of self and non-self cells in animals Involves a gene locus in angiosperms with many different alleles

Double Fertilization 1st, a pollen grain grows a pollen tube using 1 of its 2 nuclei The other nucleus in the pollen divides whiles traveling down the tube

Of those 2 nuclei, 1 fertilizes the egg to make an embryo The other fertilizes the 2 polar nuclei to make the endosperm

What the heck is endosperm? Food for the ‘baby’ supplied by ‘ mom and dad’ In most monocots and some eudicots Gives the developing embryo a food supply until it can makes its own It’s the kernel in the corn The center of the sunflower seed It’s the part animals love to eat!

The embryo consists of the epicotyl, hypocotyl, radicle, and cotyledons Seed coat Radicle Epicotyl Hypocotyl Cotyledons

From Ovary to Fruit The ovary develops into the fruit, For protection To aid in seed dispersal of seeds by wind or animals For both

Pineapple inflorescence Fruits are classified into several types Depending on their developmental origin Carpels Flower Ovary Stamen Stigma Stamen Ovule Pea flower Raspberry flower Pineapple inflorescence Carpel (fruitlet) Each segment develops from the carpel of one flower Stigma Seed Ovary Stamen Pea fruit Raspberry fruit Pineapple fruit Simple fruit. A simple fruit develops from a single carpel (or several fused carpels) of one flower (examples: pea, lemon, peanut). (a) Aggregate fruit. An aggregate fruit develops from many separate carpels of one flower (examples: raspberry, blackberry, strawberry). (b) Multiple fruit. A multiple fruit develops from many carpels of many flowers (examples: pineapple, fig). (c)

Seed dormancy allow seeds to wait for favorable conditions to begin to grow The breaking of seed dormancy may require environmental cues, such as temperature or lighting cues, & here, freezing! WHY!?

imbibition initiates germination From Seed to Seedling imbibition initiates germination Is the uptake of water due to low water potential of the dry seed Enough water to imbibe the seed signals a good environment to support the seeding

Monocots break out as … The coleoptile grows through the endosperm, then the soil, then fosters 1st leaves Foliage leaves Coleoptile Radicle

Asexual Reproductive Fragmentation Is the separation of a parent plant into parts that develop into whole plants Is one of the most common modes of asexual reproduction Cuttings Grafting Stolons and rhizomes

Plant biotechnology has two meanings It refers to innovations in the use of plants to makes plant products more useful to humans It refers to the use of genetically modified (GM) organisms in agriculture and industry Rosa rugosa

Maize Is a product of artificial selection by humans Is a staple in many developing countries, but is a poor source of protein Figure 38.14

Reducing World Hunger and Malnutrition Genetically modified plants Have the potential of increasing the quality and quantity of food worldwide Ordinary rice Genetically modified rice

Possible Effects on Nontarget Organisms Many ecologists are concerned that the growing of GM crops Might have unforeseen effects on nontarget organisms, including us! They sidestep coevolution of organisms