4. Which of the following statements concerning fertilization in ferns is true? a. It occurs within the female structure. b. It requires water. c. The fertilization product is a seed. d. It occurs within the female structure; and It requires water.
4. Which of the following statements concerning fertilization in ferns is true? a. It occurs within the female structure. b. It requires water. c. The fertilization product is a seed. d. It occurs within the female structure; and It requires water. e. It occurs within the female structure; It requires water; and the fertilization product is a seed. 5. Gametophytes are a. haploid plants that produce spores. b. diploid plants that produce spores. c. haploid plants that produce gametes. d. diploid plants that produce gametes. e. diploid or haploid plants that produce gametes. Pop Quiz!
Pop Quiz! 6. Alternation of generations refers to the • a. expression of recessive traits. • b. presence of a diploid and a haploid generation in the life cycle of plants. • c. presence of the different sexes in two different plants. • d. occurrence of a sexually reproducing diploid stage followed by an asexually reproducing haploid stage during the life cycle of higher plants.
PLANTS! Reproduction Part 2 (lecture 16) (Gymnosperms & Angiosperms)
First Seed Plants • Gymnosperm: conifers • vascular • heterospory • male vs. female gametophytes • seeds • naked seeds (no fruit) • pollen • contain male gametophyte • life cycle dominated by sporophyte stage • coniferous trees you are familiar with are diploid • reduced (microscopic) gametophyte • reduction of gametophyte protects delicate egg & embryo in protective sporophyte • protected from drought & UV radiation
Pollen • Pollen eliminated the water requirement for fertilization • spread through wind & animal Ragweed pollen…oh my itchy eyes!
sporangium & pollen male male (pollen) cones female female cones pine embryo
First Flowering Plants • Angiosperm: flowering plants • vascular • heterospory • male vs. female gametophytes • flower • specialized structure for sexual reproduction • seeds within fruit • pollen • life cycle dominated by sporophyte stage • trees & bushes you are familiar with are diploid • reduced (microscopic) gametophyte
Stigma Carpel Style Anther Ovary Stamen Filament sepals petals Petal stamens Ovule carpel Sepal Flower • Modified shoot, modified leaves • Male • sepals • petals • Stamens • Filament & anther • Female • Carpel • Stigma, style, & ovary
Pollination – transfer of pollen from the anther to a stigma If pollination occurs, a pollen tube forms The pollen tube transfers sperm to the ovule which will result in a zygote (new plant) and a 3n (triploid) nucleus that will form endosperm Endosperm is the nutrient storing tissue in a seed Flowering Plant Pollination
Seed & Plant Embryo seed coat • Seed offers… • protection for embryo • stored nutrients for growth of embryo endosperm (3n) cotyledons embryo (2n) cotyledons = “seed” leaves, first leaves of new plant
Double Fertilization • Remember: 3 Features of the Angiosperm Cycle • Flowers, Fruits, & Double Fertilization • The Process: • Pollination (pollen grain lands on stigma) • Tube Nucleus (pollen tube produced down the style) • Generative Nucleus (2 sperm form by mitosis) • Enters ovary through micropyle • 1 sperm fertilizes haploid egg to form zygote; other sperm combines with 2 polar nuclei to form 3n endosperm (food-storing tissue)
polar nuclei pollengrains egg cell 3n endosperm 2n zygote 2n embryo Angiosperm Life Cycle male gametophyte = pollen grain (haploid) dehiscence ovary sac sperm nuclei travel down pollen tube female gametophyte =ovary sac (haploid) doublefertilization new sporophytein seed(diploid)
Monocots & Dicots • Angiosperm are divided into 2 classes • dicots (eudicot) • 2 cotyledons (seed leaves) • leaves with network of veins • woody plants, trees, shrubs, beans • monocots • 1 cotyledon • leaves with parallel veins • grasses, palms, lilies
Pop Quiz! • 1. The heterosporous condition led to evolution of • a. gymnosperms and angiosperms. • b. pollen grains and seeds. • c. male and female plant parts. • d. pollen grains and seeds in male and female plant parts. • e. gymnosperms and angiosperms which bear pollen grains and seeds in male and female plant parts.
2. Which of the following produces no seeds? a.Cycads b.Conifers c.Horsetails d.Ginkgos e.Tomato 3. Microspores mature into a.ovules. b.seeds. c.pollen grains. d.anthers. Pop Quiz!
Pop Quiz! • 4. Gymnosperms • a. were the first plants not to have swimming sperm and were therefore freed from the need for water to reproduce. • b. are divided into two groups, the monocots and dicots. • c. were the first plants to develop vascular tissues. • d. were the first plants to develop flowers to attract insects.
Pop Quiz! • 5. Which of the following statements about pine cones is correct? • a. Cones are exclusively female structures. • b. Cones are the result of pollination. • c. One type of cone produces microspores. • d. Seeds are enclosed in cones. • e. One type of cone produces microspores; and seeds are enclosed in cones.