1. Plant Form and Function:
How Do Plants Live in the World?

2. What Important Events Define the History of Plant Life ?
Photosynthesis changed the world
Eukaryotic cells and multicellularity enabled plants to diversify
Plants moved from water to land
Vascular plants dominate the terrain

3. Important Events in Plant Evolution

4. Photosynthesis Changed the World
Plants use chlorophyll to capture the energy of sunlight for use in photosynthesis
Oxygen is the by-product and has accumulated over the past 2.5 billion years.

5. Evolution of Eukaryotic Cells
Occurred before plants became multicellular.
Evolution of eukaryotic cells due to endosymbiosis.
Evidence to support the theory: Mitochondria and chloroplasts.
Many examples of living prokaryotes that share features of mitochondria and chloroplasts found in eukaryotes.

6. Evolution of Multicellular Cells
Advantages of multicellularity
Cellular organisms have opportunity for cellular specialization.
Decreased vulnerability to changes in temperature, humidity, and nutrient availability that comes with increased size

7. Origin of Multicellularity
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8. Plants Moved From Water To Land
Several evolutionary adaptations made this possible:
Multicellularity.
To prevent water loss
A waxy cuticle.
An epidermal layer.
Structures that protect and enclose the delicate gametes and embryo.

9. Plants Moved From Water To Land
Several evolutionary adaptations made this possible:
Alternation of Generations
Their life cycle is divided into two stages

10. Plants Moved From Water To Land
Life cycle of vascular plants:
Have vascular tissues for moving food and water.
Includes evergreens and flowering plants.

11. Plants Moved From Water To Land
Another evolutionary adaptation that occurred in most vascular plants is
Seed formation
Has helped contribute to the success of vascular plants

12. Vascular Plants Dominate the Terrain

13. Vascular Plants Dominate the Terrain
Most successful vascular plant are angiosperms.
Most diverse
Defining characteristic is the flower.

14. What Do Plants Need and How Do They Get It?
Plant form and function is best understood in terms of their needs:
Light
Gases
Water
Nitrogen and other nutrients

15. Plants Need Light Needed for photosynthesis.
Asymmetric branch pattern allows for greatest exposure to light.
Leaf
Greatest amount of photosynthesis.
Allow for maximum light absorption
Can do solar tracking

16. Plants Need Light Leaf interior promotes light absorption
Palisade layer
Spongy mesophyll

17. Plants Need Gases Plants need carbon dioxide (CO2)
Raw material for making sugar.
Stomates allow CO2 to enter cells.
Water can be lost through stomates

18. Double-Click on the movie still for the movie to play in full.
Stomata
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19. Plants Need Gases C4 plants Can trap CO2 on hot, dry days
Trap CO2 in palisade or spongy cells
Only about 3% of plants

20. Plants Need Gases CAM plants Desert dwelling plants
Stomates must be closed all day long to prevent water loss.
Stomates only open at night
Carbon dioxide enters and is stored in 4-carbon molecule .
CO2 molecule is released during the day in order for photosynthesis to occur.

21. Plants Need Water Roots
Anchor plant to ground and absorb moisture and minerals
Root structure specially designed for absorption

22. Plants Need Water Root hairs maximize absorption.
Found on root surface
Delicate extensions dramatically increase surface area

23. Plants Need Water Arrangement of cells in the root
Water is absorbed at epidermal layer and moves from cell to cell through the cortex by diffusion

24. Plants Need Nitrogen Nitrogen-fixation
Process in which certain microbes fix atmospheric nitrogen into organic compounds.
Some plants have a symbiotic relationship with these microbes.

25. Plants Need Other Nutrients
Plants obtain minerals through their roots.
When water enters the plant roots, so do minerals.
Move up the body of the plant to the leaves and stems.

26. Plants Need Nitrogen and Other Nutrients

27. How Do Higher Plants Transport Substances and Support Themselves?
All large multicellular organisms must have some way of transporting substances through their bodies, including plants.
In some plants, the same tissues are responsible for:
Moving water
Providing support

28. Translocation The movement of fluids within the plant body Phloem
Living vascular tissue near the periphery of the stem
Made of columns of sieve tubes
Sap (sugar-rich fluids made by photosynthesis) moves through the phloem

29. Transpiration
Evaporation of water through the stomates of plant leaves.
Creates a negative pressure
Allows water to move upward plant from roots
Also prevents plants from overheating.

30. Water and Minerals Move Through the Xylem
Vascular tissue usually found nearer the core, or center, of the stem.
Composed primarily of dead cells that form a hollow interconnected network of tubules.

31. Plants Need Mechanical Support
Reaching for the sun means growing upward
Opposing gravity.
In soft-stemmed plants, mechanical support provided by turgor pressure.
In woody plants, mechanical support provide by xylem.
Reinforced with lignin.

32. How Do Plants Grow? Plant growth is indeterminate.
Occurs at the meristem
Cells divide by mitosis within meristem tissue.
Found at the
tip of shoots and roots
In periphery of the woody trees and shrubs

33. Three Main Tissue Types in Plants

34. How Do Plants Grow? Apical meristem Found at tip of shoots and roots.
Responsible for lengthwise growth.
Called primary growth.

35. How Do Plants Grow? Vascular cambium
Meristematic tissue that produces new bundles of xylem and phloem.
Increases the girth of the stem or roots.
Called secondary growth.

36. How Do Plants Grow? Cork cambium
Layer of meristem produced from cells of the ground tissues.
Produces a new layer of cells called cork.
Also contributes to secondary growth.

37. Plants Have Hormones Phototrophism
Growing plant will bend toward the light.
Due to the presence of auxins.
Class of molecules.

38. Plants Have Hormones Auxins Stimulate cell elongation.
Play a role in causing the growing plant root to bend down.
Involved in fruit development.

39. Plants Have Hormones Gibberellins
Class of 100 similar chemical compounds.
Produced at tips of roots and stems.
Stimulates plant growth.
Most concentrated in seeds.
Facilitates growth of embryo and germination.

40. Plants Have Hormones Abscisic Acid (ABA)
Hormones that slow growth
Needed on cold days or excessively hot days.
Released when water is scarce.
Plant growth is a balance between ABA and gibberellins.

41. Plants Have Hormones Ethylene Causes fruit ripening
As fruit ages, it releases more ethylene
Activates enzymes that digest the cell walls of plants.
Enables plant to respond to environment by by aging or planned cell death

42. Plants Reproduce Sexually
Zygotes are formed by the fusion of male and female gametes
In angiosperms, flowers are the sex organs that produce gametes.

43. Sexual Reproduction in Flowering Plants
Male reproductive organs = stamens
Have anthers
Contain cells that give rise to pollen

44. Sexual Reproduction in Flowering Plants
Female sex organ = carpel
First houses the ovule,
Then the female gametophyte
And finally, the embryo

45. Fertilization in Flowering Plants

46. Fertilization in Flowering Plants

47. Pollination
How does pollen get from the male anther to the female ovary?
Wind
Water
Animal pollinators
Flowers attract animal pollinators.

48. Seeds and Fruits After fertilization, ovule develops into a seed.
Seed remains dormant until conditions for growth are appropriate.
Ovary that surrounds the seed, or some other parental structure, may develop into the fruit.