Diversity Part 2: Plants

1. Diversity Part 2: Plants Chapter 24 and 25

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

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

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

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

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

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

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

10. Palisade and Spongy Mesophyll

11. Vascular Bundle

12. Vascular Bundle • 2 Main Types Of Tubes: Xylem and Phloem • Xylem- transports water and minerals from the soil up to the rest of the plant • 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

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

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.

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.

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.

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.

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

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

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.

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

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!

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

25. Tropisms • Phototropism • Heliotropism • Thigmotropism • Gravitropism

26. Phototropism • Directional movements in response to light

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

28. Thigmotropism • Plants bend when they touch an object

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