Biology - Chp 23-25 - Selected Plant Topics - PowerPoint
- 1. Selected Plant Topics Chapters 23 – 25
- 2. Specialized Tissues in Plants 23 -1
- 3. Seed Plant Structure Three of the principal organs of seed plants are roots, stems, and leaves
- 4. Roots Absorb water and dissolved nutrients Anchor plants in the ground Hold soil into place and prevent erosion
- 8. Stems Support above ground parts of plant Transports nutrients
- 9. Leaves Main photosynthetic systems Let in oxygen and carbon dioxide
- 10. Vascular Tissue Forms a transport system that moves water and nutrients throughout the plant
- 11. Types of vascular tissue Xylem – brings water and nutrients up from the roots Phloem – brings food down from the leaves
- 15. Leaf Structures and Functions Mesophyll – where photosynthesis happens Palisade mesophyll – closely packed, lots of chloroplasts Spongy mesophyll – loose tissue with many airspaces
- 17. Stomata – pore-like openings in the underside of the leaf Allow CO 2 and O 2 to diffuse in and out of the leaf
- 18. Guard Cells Control the opening and closing of the stomata by responding to changes in water pressure
- 20. Transpiration The loss of water through its leaves
- 22. Gas Exchange If stomata were kept open all the time, water loss due to transpiration would so great that few plants would be able to take in enough water to survive. Plants keep their stomata open just enough to allow photosynthesis to take place but not so much that they lose too much water. The stomata open and close in response to changes in water pressure in the guard cells
- 23. When pressure is high – stomata open When pressure is low – stomata close Q: What time of day do you think stomata are open and why? A: Daytime, cause that’s when photosynthesis happens
- 24. 24 – 1 Reproduction with Cones and Flowers
- 25. Life Cycle of Gymnosperms Reproduction in gymnosperms takes place in cones Male cones produce – pollen grains Female cones produce – ovules
- 26. Structure of Flowers Flowers are reproductive organs that are composed of 4 kinds of specialized leaves
- 28. Sepals Enclose the bud before it opens, leaf-like
- 29. Petals Brightly colored, attract insects to flower
- 30. Stamen Male reproductive structure of flower, made of 2 parts Filament – long, thin, stalk that supports the anther Anther – makes pollen grains Anther Filament Anther + Filament = Stamen
- 32. Pistil Female reproductive structure, made of 3 parts
- 33. Stigma where pollen grains land, sticky
- 34. Style Connects stigma to ovary Style
- 35. Ovary swollen base of the pistil where ovules are formed Ovary
- 36. Pollination Most gymnosperms and some angiosperms are wind pollinated, whereas most angiosperms are pollinated by animals Insect pollination is beneficial to insects and other animals because it provides them with food Plants also benefit because this method of pollination is more efficient
- 37. Q: What kind of symbiotic relationship is this? A: Mutualism
- 38. 25 – 1 Hormones and Plant Growth In plants, the division, maturation, and development of cells are controlled by a group of chemicals called hormones
- 39. Hormones A substance that is produced in one part of the organism and affects another part of the same organism
- 40. Target Cell The portion of an organism affected by a particular hormone
- 41. Auxins Discovered by Charles Darwin and his son They were trying to explain phototropism
- 42. Phototropism The tendency for plants to grow toward light
- 44. Auxins are produced in the apical meristem and are transported downward into the rest of the plant They stimulate cell elongation
- 46. Gravitropism The response of a plant to gravity
- 47. Auxin Like Weed Killers High concentrations of auxins can inhibit growth, so scientists have produced many auxin like compounds to be used as herbicide Ex.) Agent Orange
- 49. Cytokins Plant hormones that stimulate cell division , the growth of lateral buds and cause dormant seeds to sprout Cytokins often produce effects opposite to those of auxins
- 50. Gibberellins Promote growth, particularly in stems and fruits
- 51. Ethylene Stimulate fruits to ripen
- 52. 25 – 2 Plant Responses
- 53. tropisms The response of plants to external stimuli Ex.) gravitropism and photoperiodism
- 54. Thigmotropism Growth in response to touch
- 55. Rapid Responses Some plant responses do not involve growth, they are so rapid it would be a mistake to call them tropisms Ex.) sensitive plant, venus fly trap
- 56. Sensitive Plant
- 57. Venus Fly trap
- 58. Photoperiodism The way a plant responds to periods of light and darkness Short day plants – flower when days are short Long day plants – flower when days are long Photoperiodism in plants is responsible for the timing of seasonal activities of plants
- 59. Dormancy The period during which an organism’s growth and activity decrease or stop As cold weather approaches deciduous plants turn off photosynthetic pathways, transport materials from leaves to roots, and seal leaves from the rest of the plant