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End Show Slide 1 of 52 Copyright Pearson Prentice Hall Biology.

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Presentation on theme: "End Show Slide 1 of 52 Copyright Pearson Prentice Hall Biology."— Presentation transcript:

1 End Show Slide 1 of 52 Copyright Pearson Prentice Hall Biology

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

3 End Show Slide 3 of 52 24–1 Reproduction With Cones and Flowers Copyright Pearson Prentice Hall 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.

4 End Show Slide 4 of 52 24–1 Reproduction With Cones and Flowers Copyright Pearson Prentice Hall 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.

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

6 End Show Slide 6 of 52 24–1 Reproduction With Cones and Flowers Copyright Pearson Prentice Hall 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.

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

8 End Show Slide 8 of 52 24–1 Reproduction With Cones and Flowers Copyright Pearson Prentice Hall 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.

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

10 End Show Slide 10 of 52 24–1 Reproduction With Cones and Flowers Copyright Pearson Prentice Hall 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.

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

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

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

14 End Show Slide 14 of 52 24–1 Reproduction With Cones and Flowers Copyright Pearson Prentice Hall 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

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

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

17 End Show Slide 17 of 52 24–1 Reproduction With Cones and Flowers Copyright Pearson Prentice Hall 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.

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

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

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

21 End Show Slide 21 of 52 24–1 Reproduction With Cones and Flowers Copyright Pearson Prentice Hall 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

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

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

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

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

26 End Show Slide 26 of 52 24–1 Reproduction With Cones and Flowers Copyright Pearson Prentice Hall 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

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

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

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

30 End Show Slide 30 of 52 24–1 Reproduction With Cones and Flowers Copyright Pearson Prentice Hall 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.

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

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

33 End Show Slide 33 of 52 24–1 Reproduction With Cones and Flowers Copyright Pearson Prentice Hall 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.

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

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

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

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

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

39 End Show Slide 39 of 52 24–1 Reproduction With Cones and Flowers Copyright Pearson Prentice Hall Fertilization in Angiosperms If a pollen grain lands on the stigma of a flower of the same species, it grows a pollen tube. Pollen grains (N) (male gametophyte) Pollen tubes Ovule

40 End Show Slide 40 of 52 24–1 Reproduction With Cones and Flowers Copyright Pearson Prentice Hall Fertilization in Angiosperms The pollen tube grows into the style, reaches the ovary, and enters the ovule. Pollen grains (N) (male gametophyte) Pollen tubes Ovule

41 End Show Slide 41 of 52 24–1 Reproduction With Cones and Flowers Copyright Pearson Prentice Hall 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 (2N)

42 End Show Slide 42 of 52 24–1 Reproduction With Cones and Flowers Copyright Pearson Prentice Hall Fertilization in Angiosperms The other sperm nucleus fuses with two polar nuclei in the embryo sac to form a triploid (3N) cell. This cell will grow into a food-rich tissue known as endosperm, which nourishes the seedling as it grows. Endosperm (3N) Zygote (2N)

43 End Show Slide 43 of 52 24–1 Reproduction With Cones and Flowers Copyright Pearson Prentice Hall Fertilization in Angiosperms Because two fertilization events take place between the male and female gametophytes, this process is known as double fertilization.

44 End Show Slide 44 of 52 24–1 Reproduction With Cones and Flowers Copyright Pearson Prentice Hall Pollination How does pollination differ between angiosperms and gymnosperms?

45 End Show Slide 45 of 52 24–1 Reproduction With Cones and Flowers Copyright Pearson Prentice Hall Pollination Most gymnosperms and some angiosperms are wind pollinated, whereas most angiosperms are pollinated by animals.

46 End Show Slide 46 of 52 24–1 Reproduction With Cones and Flowers Copyright Pearson Prentice Hall 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

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

48 End Show Slide 48 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.

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

50 End Show Slide 50 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.

51 End Show Slide 51 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

52 End Show Slide 52 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.

53 END OF SECTION


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