1. Chapter 24 and 25 Diversity Part 2: Plants 1

2. Photosynthesis Carbon Dioxide + Water  Glucose + Oxygen How does a plant obtain the carbon dioxide it needs for photosynthesis? Pores called stomata Sunlight 2

3. Stomata Holes in the plant leaves Let in carbon dioxide needed for photosynthesis Lets out the oxygen produced as a byproduct Also lets water leave 3

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5. Guard Cells Surround the stomata They help control how much water is lost 5

6. Anatomy of a Leaf Organ Cuticle Mesophyll (Palisade and Spongy) Vascular Bundle Stomata Guard Cells Chloroplasts 6

7. Leaf Structures Cuticle Mesophyll (Palisade and Spongy) Vascular Bundle Stomata Guard Cells 7

8. Cuticle A clear, waxy layer that prevents water loss in plants Cuticle 8

9. Mesophyll The mesophyll is packed with cholorplasts, where photosynthesis occurs Most plants have leaves with 2 layers of mesophyll 1. Columnar cells = Palisade Layer 2. Loosely packed cells = Spongy Layer Mesophyll 9

10. Palisade and Spongy Mesophyll 10

11. Vascular Bundle 11

12. Vascular Bundle 2 Main Types Of Tubes: Xylem and Phloem 1. Xylem- transports water and minerals from the soil up to the rest of the plant 2. Phloem- transports sugar from the leaves to the rest of the plant The plant cells in the roots and stems need sugar from the leaves to perform cellular respiration in the mitochondria 12

13. Stomata and Guard Cells Stomata are holes in the leaves that let carbon dioxide in and oxygen out. Guard Cells surround the stomata to control water loss Stomata Guard Cells 13

14. How does Water move throughout a Plant? The primary force that pulls water up a plant is evaporation at the leaves, also called transpiration. 14

15. How Does Water Move Throughout a Plant? When water leaves the leaf, it is replaced by water from the stem – water naturally moves from high concentrations toward low concentrations in a type of passive transport called osmosis. 15

16. How Does Water Move Throughout a Plant? The whole column of water from leaf to root is pulled by this force because water molecules stick to each other, a property of water called cohesion. 16

17. How does Sugar move throughout a Plant? Leaf cells move sugar into the phloem using active transport to pack the sugar at a high concentration This high concentration of sugar solute in the phloem makes the inside the phloem cells very hypertonic This environment causes water from the xylem to rush in by osmosis. This rush of water creates a bulge, pushing the liquid to its destination. 17

18. Dormancy If the environment is not right, the seed can stay dormant for thousands of years until there are favorable conditions A plant breaks dormancy and starts to grow in a process called Germination 18

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20. Conditions Required To Break Dormancy The seed coat must be damaged or wait until favorable conditions: 1. Temperature 2. Soil moisture 3. Fire 4. Passing through the digestive system of an animal 5. Falling onto rocks 20

21. Temperature Example: Dogwoods produce mature seeds in the fall, but conditions are not suitable for seedling survival until spring when conditions are favorable for germination. 21

22. Fire or Smoke Example: Fire poppies germinate immediately following a fire. 22

23. Passing through digestive system Example: Strawberry and Raspberry seed coats pass through the digestive system of the animal still protecting the viable embryo inside, but weakened enough to allow sprouting! 23

24. Meristem A plant grows when meristem cells undergo lots of cell division (mitosis) to make more cells and grow roots / stems / leaves A plant grows taller in primary growth, so the plant can have access to sunlight quickly 24

25. Tropisms Phototropism Heliotropism Thigmotropism Gravitropism 25

26. Phototropism Directional movements in response to light 26

27. Heliotropism When the leaves of some plants track the sun as it moves across the sky 27

28. Thigmotropism Plants bend when they touch an object 28

29. Gravitropism Responses to gravity, when the stem bends up toward the sun and the roots bend down to the ground 29