CHAPTERS 31 + 32

1. CHAPTERS 31 + 32 Plant Structure and Function

2. 31.3 Three Basic Parts of a Plant:Roots, Stems, and Leaves

4. Roots • Anchors the plant in the soil • Absorbs an transports minerals and water • Stores food

5. Stem • Above the ground • Supports and separates the leaves • Flowers for reproduction • Leaves for photosynthesis

6. Leaf -“the blade” -Usually flat to receive sunlight -Veins contain water and food-conducting tubes

7. Some Leaf Vocabulary • Parenchyma = non-woody, functioning part of the plant • Chlorenchyma= photosynthesizing non-woody, functioning part of the plant

8. Leaf • Blade = usually the flat, broad organ above ground – the leaf • Midrib= central or main vein

10. Xylem Tissue • Contains two water-conducting cells: • Dead, only cell walls • Water moves only up the plant.

13. Phloem • Food conducting tubes (up and down) • Cells remain alive

15. Transpiration • Evaporation of water from mostly leaves (could also be stems). • Transpiration You Tube

16. How does the water get from the roots to the leaves? • 1. Root pressure – water absorbed in roots • 2. Mass flow of liquid water from the roots to the leaves is driven in part by capillary actionup the xylem tubes. • 3. Transpiration evaporation pulls the water up.

17. Capillary Action in Xylem • Adhesion of water to sides of xylem tubes (hydrophilic cellulose molecules via H-bonds) and cohesion of water to water molecules (H-bonds) to make a column.

18. Transpiration Pulling force of water by evaporation Guard cells control transpiration.

19. How Guard Cells Work • A stoma opens when its guard cells gain K+ ions and water by osmosis • The water vacuoles become turgid and the guard cells become bowed (inner membrane is thicker) as they fill and open the stoma

20. How the Guard Cells Work (2) • When the guard cells lose K+, they also lose water by osmosis • The water vacuoles become flaccid and less bowed • The stomata close

21. Usually • Guard cells keep stomata open during the day • CO2 enters for photosynthesis • Guard cells keep stomata closed at night • No sunlight-no photosynthesis-save water

22. 3 clues to stomatal opening at dawn • 1. SUNLIGHT-stimulates guard cells to accumulate K+ • 2. LOW LEVEL OF CO2 in the leaf • 3. BIOLOGICAL CLOCK of some sort (even if put in a dark closet, they will still open)

23. If it is a drought, WHAT HAPPENS? • The stomata will close to reduce water loss and prevent wilting. This also slows down CO2 intake and photosynthesis.

24. Root Pressure Pushes water up xylem a few meters

27. Fig. 31.2 Comparison of monocots and eudicots

28. Fig. 31.13A Bean Germination(a Eudicot)

29. Fig. 31.13B Corn Germination (a monocot)

31. Leaf Texture • Waxy Hairy • Rough

32. Leaf Shape

33. Leaf Arrangement on Stem

34. Leaf Venation