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DIVERSITY OF LIVING THINGS (PLANTS)

DIVERSITY OF LIVING THINGS (PLANTS). G9 Alpha and Delta – 2011 Mr. ARNOLD, Rafael. CROSS-SECTION OF A LEAF. CONTROLLING GAS EXCHANGE AND WATER LOSS For photosynthesis to occur properly there must be a perfect balance of materials. -Carbon dioxide gas (enters the plant coming from the air)

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DIVERSITY OF LIVING THINGS (PLANTS)

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  1. DIVERSITY OF LIVING THINGS (PLANTS) G9 Alpha and Delta – 2011 Mr. ARNOLD, Rafael

  2. CROSS-SECTION OF A LEAF

  3. CONTROLLING GAS EXCHANGE AND WATER LOSS For photosynthesis to occur properly there must be a perfect balance of materials. -Carbon dioxide gas (enters the plant coming from the air) -Oxygen (moves out to the atmosphere from the leaves) -Water vapor (moves out to the atmosphere in a process called transpiration)

  4. PHOTOSYNTHESIS

  5. GAS EXCHANGE IS PERFORMED BY STOMATA Stomata (singular: stoma) are little openings at the bottom of leaves. Function: Gas exchange (carbon dioxide comes in and oxygen goes out) and water loss by transpiration. For photosynthesis the plant needs enough carbon dioxide coming in through stomata but without losing too much water.

  6. STOMATA Stoma in tomato leaf shown via colorized scanning electron microscope image A stoma in cross-section

  7. http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/G/GasExchange.htmlhttp://users.rcn.com/jkimball.ma.ultranet/BiologyPages/G/GasExchange.html

  8. PLANT TRANSPIRATION http://click4biology.info/c4b/9/plant9.2.htm

  9. MECHANISMS TO AVOID WATER LOSS IN EXCESS. -The surfaces of leaves are covered by a cuticle (waxy protective layer) that prevents water loss. -When the air is dry and/or hot the stomata can close. -Stomata can open at night when there is less evaporation.

  10. MORE MECHANISMS TO AVOID WATER LOSS IN EXCESS. -Some plants have adaptations, for example in cacti the spines are modified leaves that loses little water (because of less surface area exposed) by evaporation. The photosynthesis occurs in the stem.

  11. ADAPTATIONS TO AVOID LOSS OF WATER IN CACTI The leaves have been reduced to needles to reduce transpiration. The stem is fleshy in which the water is stored. The stem becomes the main photosynthetic tissue. http://click4biology.info/c4b/9/plant9.2.htm#5

  12. PLANTS GROW THROUGHOUT THEIR LIFETIMES -Plants grow as long as they live. -It occurs when cells at the tips of roots and stems divide faster than the others. -Plants roots and stems grow longer, thicker and branch. -Only stems grow leaves.

  13. PLANTS GROW THROUGHOUT THEIR LIFETIMES -Leaves grow from buds produced in plant's stems. A bud is small protuberance on a stem or branch, sometimes enclosed in protective scales (modified leaves) and containing an undeveloped shoot, leaf, or flower.

  14. http://en.wikipedia.org/wiki/File:Plant_Buds_clasification.svghttp://en.wikipedia.org/wiki/File:Plant_Buds_clasification.svg

  15. PLANTS WITH SOFT STEMS Some characteristics: -The stems and leaves die when the enviromental conditions are not favourable (too cold or too dry). -They store carbohydrates in their roots. -If the conditions are good (heat, water, sunlight new stems and leaves grow.

  16. PLANTS WITH WOODY STEMS Examples: -Trees -Shrubs Characteristics: -They have tough stems that do not die each year. -The stems grow thicker and longer.

  17. -They develop a thick stem from xylem. This is wood. -The growing tissues in woody stems are located near the outer surface of the stem, right under the bark (The older part of the plant is in the center of the trunk).

  18. Mosses & Ferns

  19. MOST MOSSES AND FERNS LIVE IN MOIST ENVIRONMENTS (3.2 – 92) Plants species adapted to life on land -Evidences indicate that life appeared on Earth 3.8 billion years ago.

  20. Tiny singled-cell (unicellular organisms) and multicellular organisms lived in watery environments such as: -Warm shallow seas -Deep ocean vents (opening permitting the escape of fumes (a liquid, a gas, or steam). -Ponds (A still body of water smaller than a lake).

  21. Fossil evidence suggests that plant life did not appear on Earth until 475 million of years ago. The ancestors of plants were the first organisms to move to land Scientists believe they looked like green algae that exist today.

  22. Green algae and plants are autotrophs (producers = produce their own food by doing photosynthesis). Their cells contain chloroplasts (where photosyntesis is done).

  23. THE FIRST PLANTS The place where we are now millions of years ago could have been a pond. This pond contained: -Tiny floating organisms that could photosynthesize (the Sun provided the light). -Nutrients ( C, H, O, N, P, S)

  24. The following facts occurred: -The organisms reproduced and increased in number. -The pond became crowded. -Some of the organisms were pushed to the edges of the pond. -After a period of dry weather the pond shrank.

  25. -Some organisms were no longer in the water. -The ones that survived started to live on land and became the ancestors of the first plants. Scientists believe this process happened in millions of ponds during millions of years

  26. Some differences between life on land and life in water faced by the first plants: Disadvantages: -On land there is no water to support the plants body. -There is no water to avoid drying out. Advantage: -Plenty of carbon dioxide. -Plenty of light from the Sun.

  27. MOSSES AND FERNS -Both probably evolved from algae that lived in the sea and in freshwater. -Mosses are simpler than ferns in structure.

  28. MOSSES http://www.aquamoss.net/Introduction.htm

  29. Mosses http://www.davidlnelson.md/Cazadero/Mosses.htm

  30. http://www.countrysideinfo.co.uk/moss_article/page2.htm

  31. http://www.countrysideinfo.co.uk/moss_article/page2.htm

  32. http://www.countrysideinfo.co.uk/moss_article/page2.htm

  33. Leaves of moss http://www.davidlnelson.md/Cazadero/Mosses.htm

  34. MOSSES (SOME CHARACTERISTICS) -Their cells have a cell wall that provides support. -Most cells have areas for storage of water and nutrients (vacuoles). -They have simple structures that function as roots, stems and leaves. These structures allow mosses to live on land while algae live only in the water.

  35. MOSSES ARE NONVASCULAR PLANTS Mosses don't have vascular tissue (xylem and phloem). Water and dissolved nutrients move from cell to cell. This process is not very efficient so mosses can't be large.

  36. Mosses cells Water moves through cell to cell as mosses lack a vascular system http://www.davidlnelson.md/Cazadero/Mosses.htm

  37. CAPSULES CAPSULES IN MOSSES SPOROPHYTES http://www.sbs.auckland.ac.nz/uoa/science/about/departments/sbs/newzealandplants/mosses/

  38. FERNS ARE VASCULAR PLANTS FERNS ARE VASCULAR PLANTS FERNS ARE PLANTS Consequence: They can grow bigger much bigger than mosses

  39. FERNS REPRODUCE WITH SPORES

  40. LIKE MOSSES FERNS NEED WATER TO REPRODUCE

  41. FERNS Trunks may reach heights of 20 m. Found in moist areas on both North and South Islands in New Zealand. (photo, John Braggins) http://www.sbs.auckland.ac.nz/uoa/science/about/departments/sbs/newzealandplants/ferns/native-ferns/cyatheaceae-black-silver-ferns.cfm

  42. FERNS The stipes that support the large fronds are thick and very tough and have a characteristic black appearance. (photo, Larry Jensen) http://www.sbs.auckland.ac.nz/uoa/science/about/departments/sbs/newzealandplants/ferns/native-ferns/cyatheaceae-black-silver-ferns.cfm

  43. FRONDS OF FERNS http://www.sbs.auckland.ac.nz/uoa/science/about/departments/sbs/newzealandplants/ferns/ native-ferns/cyatheaceae-black-silver-ferns.cfm

  44. These structures are clusters. They are located on the back of the fronds. Spores are produced here by meiosis. http://www.sbs.auckland.ac.nz/uoa/science/about/departments/sbs/newzealandplants/ferns/ native-ferns/cyatheaceae-black-silver-ferns.cfm

  45. MOSSES, FERNS AND OTHER PLANTS CAN ALSO REPRODUCE ASEXUALLY • Small pieces can grow into a new plant • New plants can branch off from old ones

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