Diversity Part 2: Plants

1. Diversity Part 2: Plants Chapter 23 Introduction to Plants

2. Characteristics of Plants • Autotrophs • Multicellular • Eukaryotes • Cell Wall is made out of Cellulose

3. Photosynthesis • Chemical Equation: • CO2 + H2O  C6H12O6 + O2 • Word Equation: • Carbon Dioxide + Water  Glucose + Oxygen Sunlight Sunlight

4. Common Ancestor • The common ancestor of ALL plants is thought to be Green Algae • In the early evolution of plants, they made the transition from aquatic to land environments

5. Why Move onto Land? *Increased opportunity for photosynthesis* • Increased access to sunlight • Increased access to carbon dioxide • Increased opportunity to reproduce and disperse (spread out) But, decreased access to water as well… How did plants overcome that barrier to successfully colonize on land??

6. Importance of Mycorrhizae • Mycorrhizae is a mutualistic relationship between plants and fungito help a plant absorb water and nutrients from the soil. • This relationship helped plants transition to land.

7. Cuticle • Almost all plants have a cuticle covering their leaves and stems to prevent water loss • The cuticle is waxy (lots of lipids) and holds water in • The cuticle is also clear to let sunlight in for photosynthesis

9. Reproduction & Dispersal Once plants colonized land, certain adaptations allowed them to reproduce and disperse their offspring more effectively—this was the driving force for the evolution of plants

10. Cladogram Angiosperms Flowering Plants Gymnosperms Evergreens Seedless vascular plants Ferns Bryophytes Mosses Evolution of specialized cells / tissue Evolution of cuticle Green algae

11. Plant Groups • Bryophytes (Seedless, Non-Vascular)-Mosses • Seedless, vascular plants- Ferns • Gymnosperms- Evergreens (Pine Trees) • Angiosperms-Flowering plants

12. Mitosis is a type of cell division that makes an exact copy of the original cell Can be Haploid to Haploid or Diploid to Diploid Meiosis is a type of cell division that makes cells with Half the number of chromosomes as the original cell Can only be Diploid to Haploid

13. Plant Life Cycles:Alternation of Generations • An alternation between two distinct forms or generations that reproduce differently • One generation is haploid and reproduces sexually • The other generation is diploid and reproduces asexually

14. Alternation of Generations Multicellular diploid organism(2n) sporophyte mitosis meiosis Unicellular diploid zygote(2n) Unicellular haploid cells(n) (spores) fertilization Unicellularhaploid gametes(n) mitosis Multicellularhaploid organism(n) mitosis gametophyte

15. Moss Life Cycle Moss Life Cycle

16. Alternation of Generations By definition, all plants alternate generations Gametophyte makes gametes n=haploid Sporophyte makes spores 2n=diploid

17. Alternation of Generations Gametophyte and Sporophyte Notice that the more advanced plants have a dominant Sporophyte The less advanced plants have a more dominant Gametophyte

18. Cladogram Gymnosperms Angiosperms Seedless vascular plants Bryophytes Evolution of specialized cells / tissue Example: cuticle Green algae

19. Non-Vascular Plants • Bryophytes • Example: Moss

21. Bryophytes • They are small and low to the ground because they do not have vascular tissue • Found only in damp, moist areas on land • 1) Leaves must absorb water for photosynthesis • 2) Sperm swims through water to reach egg in gametophyte

22. Bryophytes sporophyte gametophyte

23. Cladogram Gymnosperms Angiosperms Seedless vascular plants Bryophytes Evolution of vascular tissue Evolution of specialized cells / tissue Evolution of cuticle Green algae

24. Seedless Vascular Plants • Example: Ferns

26. Key Adaptation over Nonvascular Plants • Vascular Tissue • Set of tubes that transport materials around plant • Allows plants to grow taller • Water travels up through Xylem • Sugar/Food travels throughout in Phloem

28. Ferns Can Live Further Inland • Still must live in moist areas • Sporophyte grows successfully with vascular tissue • But sperm must still swim to egg in tiny gametophyte

29. Fern Sporophyte

30. Fern Gametophyte

31. Fern Life Cycle Fern Life Cycle

32. Cladogram Gymnosperms Angiosperms Seedless vascular plants Evolution of pollen grains / seeds Bryophytes Evolution of vascular tissue Evolution of specialized cells / tissue Evolution of cuticle Green algae

33. Seed Plants • Gymnosperms/Angiosperms • Example: Pine Trees or Flowers

34. Gymnosperms • Examples: Spruce Tree, Fir Tree, Pine Tree

35. Gymnosperms • Think cones (any conifer like pine trees) female ovary male pollen cone

36. Pine treeGymnosperms tiny gametophyte inside cone sporophyte Sporophyte Dominates

37. Gymnosperm Pollen Strategy • Release a lot, hope some pollinate • (Meanwhile, irritating everyone else) • Pollen is the male sperm in Gymnosperms and Angiosperms

38. Key Adaptations Over Seedless Plants • Seeds • Pollen Grains

39. Seeds • Tough coat protects newly fertilized embryo • Also contains supply of food (endosperm) to survive during dormancy period • A seed in a gymnosperm is inside the cone

41. Seed Dispersal Plants try to disperse offspring far away so they have a higher chance of survival. Dispersal of seeds prevents competition for water, nutrients, light, and living space.

43. Seed Dispersal • Dispersal by wind – wing-like structures, parachute-like structures

44. Seed Dispersal • Dispersal by animals – fruits have hooks that cling on animals fur, other fruits provide food for animals

45. Seed Dispersal • Seeds dispersal is completed by birds, small animals, wind, and water • The tough, fibrous outer covering of a coconut provides protection as well as a floatation device

46. Pollen Grain • Hard covering around sperm, light weight allows travel by wind • Removes water requirement for fertilization

47. Pollen Grain Sperm • At the very end when pollen lands on another plant of the same species • Pollen tube connects to ovary, fertilizing egg

48. Cladogram Gymnosperms Angiosperms Evolution of flowers / fruits Seedless vascular plants Evolution of pollen grains / seeds Bryophytes Evolution of vascular tissue Evolution of specialized cells / tissue Evolution of cuticle Green algae

49. Angiosperms • Think flowers • Most diverse plant group • Most Dominant Plant group on the planet

50. Key Adaptation Over Gymnosperms • Flowers • Adapted for pollination by animals • Attract animals to help carry pollen to the next flower • Color or scent attractors guide animals to obtain sugar from plant • Some angiosperms still wind pollinate (grass)