Development of Plants (What Are the Details of Reproduction in Flowering Plants?)
2. Regarding the gametophyte generation of flowering plants: (1) Explain how and where pollen grains and ovules are produced. (2) Explain the role of spores in the above processes. (3) Indicate the location of eggs and sperm.
(1) Pollen grain: Microspore --> mitotic division-->two cells. One=tube cell (stores proteins and lipids that are needed for gametophyte development). Ovule: In the ovary of flower pistil. Within the ovule, gametophye -->megaspore. Female gametophyte = 8 cells: 3 at each end of a small sac and 2 in the center. The central cell @ bottom = egg. (2) Spores were produced by meiosis. The spores develop into the reproductive organ (pollen grain or ovule) (3) Eggs located within the ovule Sperm developed in Anthers/ Stamen
3. Regarding pollination: (1) Indicate two ways in which pollen can reach the pistil and how flowers are specialized to promote each method. (2)Indicate the purpose of the pollen tube and factors that control its growth; what is self-incompatability? (3) Describe the process of double fertilization; name the two end products and indicate the function of each.
(1) Insect pollination is very common in flowering plants -Flower shapes are designed to facilitate pollination by a specific insect, so flower color, scent, and nectar are produced to attract the insect Wind: the anthers protrude above the rest of the flower to catch the wind. Pollen grains are blown from the anthers to the stigma of another flower. (2) Pollen Tube: Helps to move sperm cells toward ovules. -Controlled by the pistil. Growth = prevented if the genotype of the pollen grain & pistil too similar. -Self-incompatibility: If allele in haploid pollen matches either allele in diploid pistil, pollen tube=NO GO. (Pollen grains w/ different alleles grow). (3) pollen tube --> micropyle. Two sperm nuclei enter sac. One fert Egg --> diploid zygote Other fuses w/in the two central nuclei with the ovule --> triploid (endosperm).
4. Regarding seeds and fruit: (1) Indicate how (from which part of the flower) each originated. (2) Describe (or draw) the internal structure of a corn seed and a bean seed; how does the location of endosperm differ in these seeds? (3) Describe several types of fruit and the various ways that each fruit facilitates seed dispersal.
(1) Seeds: double fertilization has occurred, the fertilized ovules --> seeds Fruit: Ovary takes up water, sugar and other compounds. The ovary wall thickens to become the fruit (2) Corn: both male and female flowers on the same plant. Stamens, but no pistils. No petals. Female flowers-->on the cob. Ovaries=dry seeds (kernels). Stigma on on corn silk. Female= no stamen, no petals. Bean Seed .... (3) - birds that eat blackberries swallow the seeds. -Coconut floats -Pods open and drp their seeds -Weeds = sticky fruit to stick to animals -Maple Seed flow with the wind ("wings")
5. Indicate the fundamental difference between sexual and asexual reproduction and give two examples of asexual reproduction in flowering plants.
Asexual= new plant via single parent. No meiosis or Fertilization. 1) tiny plantlets have formed along the leaf edges of the kalanchoe plant 2) Strawberry=runners along spoil surface--> new plants
1. Draw a "typical" flower, label the parts and give the function of each in sexual reproduction.
Stamens: Male parts of the flower. Enlarged tip=Anther (pollen grains are formed). Pistil = three parts. -Ovary: at the base houses the female gametophyte. -Style: long stalk which bears the stigma. -Stigma: designed to trap pollen as a prelude to fertilization.
