Reproduction of Flowering Plants: Structure, Pollination, and Fertilization

1. KEY CONCEPTReproduction of flowering plants takes place within flowers.

2. Sepals and petals are modified leaves. Sepals are outermostlayer that protectsdeveloping flower sepal Flowers contain reproductive organs protected by specialized leaves.

3. petal • Petals can help to attract animal pollinators

4. stamen filament anther • A stamen is the male structure of the flower. • anther produces pollen grains • filament supports the anther

5. stigma style carpel ovary • The innermost layer of a flower is the female carpel. • stigma is sticky tip • style is tube leading from stigma to ovary • ovary produces female gametophyte

6. Flowering plants pollinated when pollen grains land on stigma. Wind pollinated flowers have small flowers and large amounts of pollen. Flowering plants can be pollinated by wind or animals.

7. many flowering plants pollinated by animal pollinators • Animal pollinated flowers have larger flowers and less pollen. pollen grains • pollination occurs as animal feeds from flower to flower • animal pollination more efficient than wind pollination

8. Fertilization takes place within the flower. • Male gametophytes, or pollen grains, are produced in the anthers. • male spores produced inanthers by meiosis • each spore divides bymitosis to form twohaploid cells • two cells form asingle pollen grain pollen grain

9. four female spores produced in ovule by meiosis one spore develops into female gametophyte female gametophyte contains seven cells one cell has two nuclei, or polar nuclei one cell will develop into an egg • One female gametophyte can form in each ovule of a flower’s ovary.

10. Pollination occurs when a pollen grain lands on a stigma. pollen tube sperm stigma • one cell from pollen grain forms pollen tube • other cell forms two sperm that travel down tube

11. Flowering plants go through the process of double fertilization. female gametophyte egg sperm polar nuclei ovule

12. endosperm seed coat embryo • Flowering plants go through the process of double fertilization. • one sperm fertilizes the egg • other sperm unites with polar nuclei, forming endosperm • endosperm provides food supply for embryo

13. Each ovule becomes a seed. • The surrounding ovary grows into a fruit.

14. Animals, wind, and water can spread seeds. • Seeds dispersed by animals can have nutritious fruits or fruits that cling.

15. Cypselae Double samaras • Seeds dispersed by wind can have wing- or parachute-like fruits. • Seeds dispersed by water can have fruits that float.

16. Seed dormancy is a state in which the embryo has stopped growing. Seeds begin to grow when environmental conditions are favorable. • Dormancy may end when conditions are favorable. • While dormant, embryo can withstand extreme conditions.

17. Germination begins the growth of an embryo into a seedling. • water causes seed to swell and crack coat • embryonic root, radicle, is first to emerge • water activates enzymes that help send sugars to embryo

18. Germination begins the growth of an embryo into a seedling. water causes seed to swell and crack coat embryonic root, radicle, is first to emerge water activates enzymes that help send sugars to embryo embryonic shoot, plumule, emerges next • leaves emerge last

19. Once photosynthesis begins, the plant is called a seedling.

20. Hormones are chemical messengers. produced in one part of an organism stimulates or suppresses activity in another part Plant hormones regulate plant functions.

21. Gibberellins are plant hormones that produce dramatic increases in size. • ending seed dormancy • rapid growth of young seedlings • rapid growth of some flower stalks

22. some fruits picked before they are ripe sprayed with ethylene to ripen when reach destination • Ethylene causes the ripening of fruits.

23. final stage in cell division produced in growing roots, seeds, and fruits involved in growth of side branches • Cytokinins stimulate cytokinesis.

24. Auxins lengthen plant cells in the growing tip. • stimulates growth of primary stem • controls some forms of tropism • A tropism is the movement of plant in response to an environmental stimulus.

25. Went's Experiment Explore the steps involved in an experiment performed by Dutch botanist Frits Went.

26. Plants can respond to light, touch, gravity, and seasonal changes. • Phototropism is the tendency of a plant to grow toward light. • auxins build up on shaded side of stem • cells on shaded side lengthen • causes stem to bend toward light

27. climbing plants and vines plants that grow in direction of constant wind • Thigmotropism is a plant’s response to touchlike stimuli. Thigmotropism A plant turns and bends in response to contact with an object.

28. positive gravitropism is downward growth (roots) negative gravitropism is upward growth (shoots) • Gravitropism is a plant’s response to Earth’s gravitational pull. Gravitropism Plant stems grow upward, against gravity.

29. triggers some plants to flower (see below) triggers fall colors/winter dormancy of deciduous trees • Photoperiodism is a response to the changing lengths of day and night. Photoperiodism A plant moves its leaves during the day.