1. KEY CONCEPT Reproduction of flowering plants takes place within flowers.

2. Flowers contain reproductive organs protected by specialized leaves.
Sepals and petals are modified leaves.
Sepals are outermost layer that protects developing flower
sepal

3. Petals can help to attract animal pollinators

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

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

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

7. Animal pollinated flowers have larger flowers and less pollen.
many flowering plants pollinated by animal pollinators
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 in anthers by meiosis
each spore divides by mitosis to form two haploid cells
two cells form a single pollen grain
pollen grain

9. One female gametophyte can form in each ovule of a flower’s ovary.
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

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
ovule
egg
sperm
polar nuclei

12. Flowering plants go through the process of double fertilization.
endosperm
seed coat
embryo
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. Seeds dispersed by wind can have wing- or parachute- like fruits.
Seeds dispersed by water can have fruits that float.
Cypselae
Double samaras

16. Seeds begin to grow when environmental conditions are favorable.
Seed dormancy is a state in which the embryo has stopped growing.
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. Plant hormones regulate plant functions.
Hormones are chemical messengers.
produced in one part of an organism
stimulates or suppresses activity in another part

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

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

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

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

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