3. REVIEWREVIEW

4. Pollination Pollination is the transfer of pollen to the surface of the stigma

9. Pollination Self pollination may occur if the pollen arrives at the stigma of the same flower or another flower on the same plant

11. Pollination Cross pollination occurs when the pollen arrives at the stigma of a flower of another plant of the same species

12. Pollination Insects, wind, birds or other agents are often required for the transfer

16. Fertilization After pollination, a pollen tube forms, producing a path that the sperm will follow to the egg (in the ovary)

18. When the pollen tube penetrates the ovary, two sperm are released to accomplish “double fertilization” LOOK! TWO SPERM!

19. One sperm fuses with the egg nucleus to form a zygote The other sperm fuses with endosperm nuclei, which will develop into the parts of the seed that nourish the young seedling

20. (then, a seed develops)

21. Seeds

22. What is a seed? A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. The formation of the seed completes the process of reproduction in seed plants.

23. Why are seeds advantageous for plants? maintain dormancy until better environmental conditions arise afford protection to young plant at vulnerable developmental stage contain adequate food supply until photosynthesis is possible dispersal of plants

24. SEED STRUCTURE External –Seed coat (testa) –Hilum Embryo –Cotyledon –Epicotyl / Hypocotyl –Pumule –Radical

25. Seed Coat AKA testa The seed coat protects the embryo Can be of varying thicknesses, depending on the seed type.

26. Hilum Scar from the seed being attached to the parent plant

27. Embryo The embryo is what forms the new plant once the opportune conditions are present.

28. Cotyledon The cotyledon is the first leaf that germinates. It is filled with stored food that the plant uses before it begins photosynthesis. Some plants have 1 cotyledon (monocot) and some have 2 cotyledons (dicot).

29. Epicotyl /Hypocotyl The basis for the plant’s stem. It is known as the epicotyl above the cotyledon and a hypocotyl below the cotyledon. These grow upward in response to light.

30. Plumule The shoot tip with a pair of miniature leaves.

31. The Radicle The part of the seed where the root develops.

32. SEED DISSECTION MATERIALS –Soaked bean seed –Dissecting microscope –Tweezers –Ruler

33. SEED DISSECTION EXTERNAL –Draw the external bean –Label structures from notes INTERNAL –Carefully remove the seed coat. –Gently pull apart the two halves of the seed. –Examine each half with the dissecting microscope –Draw what you see inside the bean –Label structures from notes REVIEW THE RULES FOR LAB DRAWING BE SURE YOU MEASURE AND RECORD THE LENGTH OF YOUR SEED

34. Plumule Cotyledon Embryo Hypocotyl Epicotyl Radicle

36. Seed Dispersal  Seed dispersal is the movement or transport of seeds away from the parent plant.  Seeds are dispersed so as to avoid competition and increase chances of germination.  Seeds that fall and sprout beneath the parent plant have little chance of competing successfully for nutrients.  Seed dispersal is the movement or transport of seeds away from the parent plant.  Seeds are dispersed so as to avoid competition and increase chances of germination.  Seeds that fall and sprout beneath the parent plant have little chance of competing successfully for nutrients.

38. Germination Germination is the process by which a seed or spore sprouts and begins to grow.

39. How Germination Happens The first organ to emerge from the germinating see is the radicle, the embryonic root.

40. How Germination Happens The shoot breaks through the soil surface. In many eudicots, a hook forms in the hypocotyl, and growth pushes the hook above ground.

41. How Germination Happens Stimulated by light, the hypocotyl straightens, raising the cotyledons and epicotyl. The epicotyl now spreads its first foliage leaves, which become green and begin making food by photosynthesis.

43. What’s Required for Germination?  Water:  Imbibition means the uptake of water. Causes the seed to expand and rupture the seed coat. Water uptake triggers the release of hormones called gibberellins (GA for short) which signal enzymes to begin digesting the storage materials of the endosperm or cotyledons, and the nutrients are transferred to the growing regions of the embryo. For example, GA triggers the release of α- amylase, an enzyme that breaks down starch.

44. What’s Required for Germination?  Oxygen  Germinating seeds are very metabolically active. For example: α – amylase is breaking down storage sugars (such as starch) and converting them to other forms more useful to the seed. Oxygen is necessary for this process. If the soil is waterlogged, it might cut off the necessary oxygen supply and prevent the seed from germinating.

45. Growth Remember Differentiated plant cells generally cannot divide or produce cells of a different type. Growth can only occur at the meristem. A meristem is the tissue in all plants consisting of undifferentiated cells (meristematic cells) found in zones of the plant where rapid mitosis provides new cells. As these cells differentiate, they provide new plant tissue.

46. Apical Meristems Found in the stem of buds and growing root tips that enable the plant to grow longer.

47. Lateral Meristems (AKA Cambium) Surround the established stem of a plant and causes them to grow laterally (larger in diameter). There are two kinds: vascular cambium cork cambium

48. Phototropism Plants can control their direction of growth towards or away from environmental stimuli.