1. Reproduction of Seed Plants
Chapter 24: Biology II

2. Alternation of Generations
Diploid sporophyte generation alternates with a haploid gametophyte generation
Gametophyte plants produce male and female gametes: sperm and eggs
Gametes join  zygote
Zygote begins the next sporophyte generation

3. Life Cycle of Gymnosperms

4. Life Cycle of Gymnosperms
Pollen cone: cone that produces male gametophytes in the form of pollen grains
Seed cone: cone that produces female gametophytes
Ovule: structure in seed cones in which female gametophytes develop

5. Pollination
The gymnosperm life cycle typically takes 2 years to complete
Male cones release pollen grains and fertilizes some female cones
Pollen tube: structure grown by a pollen grain; contains two haploid sperm nuclei
Fertilization produces a diploid zygote; the new sporophyte plant
The zygote embryo develops in a seed

6. Structure of Flowers Sepals Petals Stamens Carpels
Reproductive organs composed of 4 kinds of specialized leaves:
Sepals
Petals
Stamens
Carpels

7. Sepal
Outermost circle of flower parts that encloses a bud before it opens and protects the flower while it is developing

8. Petal
Brightly-colored structure just inside the sepals; attracts insects and other pollinators to a flower

9. Stamen Male part of the flower Anther Filament
flower structure in which haploid male gametophytes are produced
Filament
a long, thin structure that supports and anther

10. Carpel Female part of the flower Pistil Stigma Style Ovary
Several carpels fused together
Stigma
sticky portion at the top of the style where pollen grains frequently land
Style
supports the stigma
Ovary
a flower structure that contains one or more ovules from which female gametophytes are produced

11. Perfect Flower
Male and female parts on the same flower

12. Life Cycle of Angiosperms
Reproduction takes place within the flower
After pollination and fertilization, the seeds develop inside protective structures (fruit)
The mature sporophyte produces flowers
Each flower contains anthers and an ovary
4 pollen grains are produced from the anther (male)

13. Life Cycle of Angiosperms
The ovary contains ovules, in which the female gametophyte develops
Embryo sac: female gametophyte within the ovule of a flowering plant
If fertilized, a zygote will form and grow into a new sporophyte plant

14. Pollination
Most angiosperms are pollinated by animals; i.e. insects, birds and bats
Flowers have bright colors, sweet nectars, etc.
Insect pollination increases chance that genes will be passed on

15. Fertilization
A pollen grain lands on the stigma of an appropriate flower, producing a pollen tube
Endosperm: food-rich tissues that nourishes a seedling as it grows

17. Fertilization
Double fertilization: fertilization in angiosperms, in which two distinct fertilization events take place between the male and female gametophytes

18. Seed and Fruit Development
As seeds mature, the ovary walls thicken to form a fruit that encloses the developing seeds
Fruit: ripened ovary that contains angiosperm seeds

19. Seed Dispersal
Animals
Wind
Water

20. Seed Dormancy
Period of time during which a plant embryo is alive but not growing
Environmental factors such as temperature and moisture can cause a seed to end dormancy and germinate

21. Seed Germination
Early growth stage of a plant embryo

22. Vegetative Reproduction
Method of asexual reproduction used by many flowering plants
Naturally occurring in many plants
A technique used by many horticulturalists to produce many copies of an individual plant
Production of new plants from horizontal stems, plantlets and from underground roots

23. Plant Propagation Identical copies of a plant are made
Offspring produced from seedless plants
Cutting
Grafting: use of a stem as a scion
Budding: process of attaching a bud to a plant to produce a new branch

24. Agriculture
Most of the people of the world depend on a few crop plants such as wheat, rice, and corn for the bulk of their food supply