Biology Slide 1 of 52 Copyright Pearson Prentice

Biology Slide 1 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Slide 2 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Alternation of Generations All plants have a life cycle in which a diploid sporophyte generation alternates with a haploid gametophyte generation. Male and female gametes of a gametophyte plant join and form a zygote that begins the next sporophyte generation. In some plants, the two stages of the life cycle are distinct, independent plants. Slide 3 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Alternation of Generations In seed plants, gametophytes are found within tissues of the sporophyte plant. In gymnosperms, they are found inside cones. In angiosperms, they are found inside flowers. Cones and flowers represent two different methods of reproduction. Slide 4 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Life Cycle of Gymnosperms What are the reproductive structures of gymnosperms? Slide 5 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Life Cycle of Gymnosperms Reproduction in gymnosperms takes place in cones, which are produced by a mature sporophyte plant. Gymnosperms produce two types of cones: pollen cones and seed cones. Slide 6 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Life Cycle of Gymnosperms Pollen Cones and Seed Cones Pollen cones produce the male gametophytes, also called pollen grains. Pollen grain (N) (male gametophytes) Slide 7 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Life Cycle of Gymnosperms Seed cones produce female gametophytes and are generally larger than pollen cones. Female gametophytes develop in two ovules located near the base of each scale. Slide 8 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Life Cycle of Gymnosperms Within the ovules, meiosis produces haploid cells that grow and divide to produce female gametophytes. Each gametophyte contains egg cells. Slide 9 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Life Cycle of Gymnosperms Pollination The gymnosperm life cycle typically takes two years to complete. The cycle begins as male cones release pollen grains. Pollen grains are carried by the wind and reach female cones. Slide 10 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Life Cycle of Gymnosperms Meiosis Fertilization Slide 11 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Life Cycle of Gymnosperms Male Cones Pollen cone Mature sporophyte Pollen grain (N) (male gametophytes) Slide 12 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Female Cones Life Cycle of Gymnosperms Cone scale Diploid cell (2 N) Ovule Seed cone Ovules Four haploid cells (N) Female gametophyte (N) Mature sporophyte Slide 13 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Life Cycle of Gymnosperms If pollen grains land on and enter an ovule, pollination occurs. A pollen tube grows out of each pollen grain and releases sperm near an egg. Egg cells Discharged sperm nucleus Pollen tube Copyright Pearson Prentice Hall Slide 14 of 52

24– 1 Reproduction With Cones and Flowers Life Cycle of Gymnosperms Fertilization produces a diploid zygote which develops into a new sporophyte plant. Zygote (2 N) (new sporophyte) Slide 15 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Life Cycle of Gymnosperms This zygote grows into an embryo and is encased within what will develop into a seed. Gametophyte tissue Embryo (2 N) Seed coat (old sporophyte) Seed Copyright Pearson Prentice Hall Slide 16 of 52

24– 1 Reproduction With Cones and Flowers Life Cycle of Gymnosperms The seed is then dispersed by wind. When conditions are favorable, the seed germinates and its embryo grows into a seedling. Slide 17 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Structure of Flowers What are the reproductive structures of angiosperms? Slide 18 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Structure of Flowers are reproductive organs that are composed of four kinds of specialized leaves: sepals, petals, stamens, and carpels. Slide 19 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Structure of Flowers Sepals enclose the bud before it opens and protect the flower while it is developing. Sepal Slide 20 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Structure of Flowers Petals are often brightly colored and are found just inside the sepals. Petals attract insects and other pollinators to the flower. Petal Slide 21 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Structure of Flowers The male parts of a flower consist of an anther and a filament, which together make up the stamen. Anther Stamen Filament Slide 22 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Structure of Flowers An anther is an oval sac where meiosis takes place, producing pollen grains. Anther Slide 23 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Structure of Flowers The filament is a long, thin stalk that supports an anther. Filament Slide 24 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Structure of Flowers The innermost floral parts are carpels, also called pistils, which produce the female gametophytes. Stigma Style Carpel Ovary Slide 25 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Structure of Flowers Each carpel has a broad base forming an ovary. The ovary contains one or more ovules where female gametophytes are produced. Ovary Ovule Copyright Pearson Prentice Hall Slide 26 of 52

24– 1 Reproduction With Cones and Flowers Structure of Flowers The narrow stalk of the carpel is the style. Style Slide 27 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Structure of Flowers At the top of the style is the stigma—a sticky portion where pollen grains frequently land. Stigma Slide 28 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Structure of Flowers Parts of a Typical Flower Stamen Stigma Anther Filament Style Carpel Ovary Petal Sepal Ovule Copyright Pearson Prentice Hall Slide 29 of 52

24– 1 Reproduction With Cones and Flowers Structure of Flowers A typical flower produces both male and female gametophytes. In some plants, male and female gametophytes are produced in separate flowers on the same individual. Slide 30 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Life Cycle of Angiosperms Reproduction in angiosperms takes place within the flower. Following pollination and fertilization, the seeds develop inside protective structures. Slide 31 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Life Cycle of Angiosperms Slide 32 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Life Cycle of Angiosperms Each flower contains anthers and an ovary. Inside the anthers, each cell undergoes meiosis and produces haploid spore cells. Each spore cell becomes a single pollen grain. Slide 33 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers The pollen grain usually stops growing until it is released from the anther and deposited on a stigma. Life Cycle of Angiosperms Pollen grains (N) (male gametophyte) Stigma Slide 34 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Life Cycle of Angiosperms In the ovule, a single diploid cell undergoes meiosis to produce four haploid cells. Haploid cell (N) Ovule Ovary (2 N) Copyright Pearson Prentice Hall Slide 35 of 52

24– 1 Reproduction With Cones and Flowers Life Cycle of Angiosperms Embryo sac (N) (female gametophyte) Only one of the four cells undergoes mitosis to produce eight nuclei. The eight nuclei and the surrounding membrane are called the embryo sac. Sperm Pollen tube Egg cell Polar nuclei Slide 36 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Life Cycle of Angiosperms Embryo sac (N) (female gametophyte) The embryo sac is the female gametophyte. One of the eight nuclei is the egg nucleus—the female gamete. Sperm Pollen tube Egg cell Polar nuclei Slide 37 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Life Cycle of Angiosperms When fertilization takes place, this cell becomes the zygote that grows into a new sporophyte plant. Endosperm (3 N) Zygote (2 N) Slide 38 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Pollination How does pollination differ between angiosperms and gymnosperms? Slide 39 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Pollination Most gymnosperms and some angiosperms are wind pollinated, whereas most angiosperms are pollinated by animals. Slide 40 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Pollination Wind pollination • is less efficient than animal pollination • relies on weather Animal pollination • plants have bright colors and sweet nectar to attract animals • benefits both the plants and the animals that pollinate them Slide 41 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Fertilization in Angiosperms Pollen grains (N) (male gametophyte) Pollen tubes If a pollen grain lands on the stigma of a flower of the same species, it grows a pollen tube. Ovule Slide 42 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers The pollen tube grows into the style, reaches the ovary, and enters the ovule. Fertilization in Angiosperms Pollen grains (N) (male gametophyte) Pollen tubes Ovule Slide 43 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Life Cycle of Angiosperms One of the sperm nuclei fuses with the egg nucleus to produce a diploid zygote. The zygote will grow into the new plant embryo. Zygote (2 N) Slide 44 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Fertilization in Angiosperms The other sperm nucleus fuses with two polar nuclei in the embryo sac to form a triploid (3 N) cell. This cell will grow into a food-rich tissue known as endosperm, which nourishes the seedling as it grows. Endosperm (3 N) Zygote (2 N) Slide 45 of 52 Copyright Pearson Prentice Hall

24– 1 Reproduction With Cones and Flowers Fertilization in Angiosperms Because two fertilization events take place between the male and female gametophytes, this process is known as double fertilization. Slide 46 of 52 Copyright Pearson Prentice Hall

24– 1 Click to Launch: Continue to: - or - Slide 47 of 52 Copyright Pearson Prentice Hall

24– 1 In a gymnosperm, fertilization occurs inside the a. ovule. b. pollen tube. c. seed cone. d. pollen cone. Slide 48 of 52 Copyright Pearson Prentice Hall

24– 1 The pollen-producing structure of angiosperms is the a. stigma. b. carpel. c. anther. d. sepal. Slide 49 of 52 Copyright Pearson Prentice Hall

24– 1 In an angiosperm, a structure that results from fertilization is the a. female gametophyte. b. pollen grain. c. zygote. d. ovary. Slide 50 of 52 Copyright Pearson Prentice Hall

24– 1 Which term applies to the chromosome number of a seed plant embryo? a. haploid b. diploid c. triploid d. polyploid Slide 51 of 52 Copyright Pearson Prentice Hall

24– 1 Pollination in most gymnosperms and some angiosperms is carried out by a. water transport. b. insects. c. wind. d. birds and bats. Slide 52 of 52 Copyright Pearson Prentice Hall

END OF SECTION