Secondary Growth

1. Secondary Growth

2. Secondary Growth • Two types of growth • Primary growth: up and down. Generated by apical meristems. Form _________ tissues • Secondary growth: growth in girth. Generated by lateral (secondary meristems). Form __________ tissues. • All plants do primary growth • Woody plants do __________ growth

3. Secondary Growth • Lateral meristems • 1) ______________: makes new phloem and xylem • Called ________ phloem and xylem tissues (vs. primary phloem and xylem made directly from procambium) • Function: xylem takes water + minerals to leaves, phloem takes sugars to roots

4. Secondary Growth • Lateral meristems • 2) ___________: makes new cell type, cork cell. Cork cells with primary wall impregnated with waxy material (_______). Dead at maturity. Forms waterproof layer on outside of body to replace epidermis. • _________: Tissue composed of cork cells and made by cork cambium. Also is a secondary tissue.

5. Secondary Growth • Stem cross section

6. Secondary Growth • Vascular bundles contain __________________ • Located between primary xylem and phloem • Meristematic: can still do _______________

7. Secondary Growth • Residual procambium cells start to divide • Produce new cells ______________

8. Secondary Growth • Parenchyma cells between bundles also start to divide • Together form solid ring of cells, all dividing laterally • This is __________________

9. Secondary Growth • Vascular cambium makes secondary xylem on __________, secondary phloem on __________ • Note how cambium moves outward over time

10. Secondary Growth • Note arrangement of primary phloem and secondary phloem, primary xylem and secondary xylem

11. Secondary Growth • Secondary xylem may contain: • 1) Vessel elements • 2) Tracheids • 3) ____________ • 4) Fibers • Secondary phloem may contain: • 1) Sieve tube elements • 2) Companion cells • 3) Parenchyma • 4) ___________

12. Secondary Growth • Two

13. Secondary Growth • Later secondary growth

14. Secondary Growth • First cork cambium: Forms under ___________

15. Secondary Growth • Cork cambium: Makes files of cork cells to outside. Forms first __________. Epidermis cut off from rest of stem and dies.

16. Secondary Growth • Problem: cork cells are dead at maturity. Cork layer cannot _________ as vascular cambium continues to grow. • Solution: form new ______ ______ in cortex under old one • After time, several __________ build up (yellow lines). Newest (inner) one cuts off water to layers beyond it and they _______.

17. Secondary Growth • Periderm replaces epidermis. How get _______ into stem?

18. Secondary Growth • Lenticels: Loosely packed __________. Allow oxygen to diffuse into stem to support living cells there.

19. Secondary Growth • Note ____ made by vascular cambium: Form ________ transport system (often parenchyma cells) • In phloem: phloem ray • In xylem: xylem ray (wood ray)

20. Secondary Growth • In temperate zone, cambium activity varies between _____ and ______ in growing season • Spring: big cells (_______ wood). • Summer: small cells (_______ wood). • Form growth ring (tree ring): one season’s growth • Ex, pine (mostly tracheids)

21. Secondary Growth • Ex, oak (note vessels, thick-walled _________)

22. Secondary Growth • Young tree section: Note rays here (phloem and xylem) • Also note growth rings: early and late wood • How old was this stem when cut?

23. Secondary Growth • In older tree: wood is secondary xylem • Heartwood: old non-functional xylem • ________: younger often functional xylem

24. Secondary Growth • Bark: From vascular cambium outward • ___________: From current cork cambium outward (all is dead) • __________: From vascular cambium to current cork cambium. Contains functional secondary phloem

25. Secondary Growth • Removing inner bark is deadly: girdling tree often will kill it • Why? Roots ______ • Why? No ________ from leaves.

26. Secondary Growth • Flow chart, showing how primary and secondary tissues develop in stem

27. Secondary Growth • Note that roots of woody plants also do secondary growth • Vascular cambium forms from __________ • First cork cambium forms in _____________.

28. Secondary Growth • So outer cortex and epidermis are sloughed off and lost

29. Uses of Growth Rings • 1) Fire frequency • Break in bark (_________) allows fire to burn through vascular cambium into wood • Leaves burned layer • If tree survives, can have record of fires in wood. Ponderosa pine, WY

30. Uses of Growth Rings • 1) Fire frequency • Helpful information when trying to determine “natural” frequency of fires for managing forests.

31. Uses of Growth Rings • 2) Climate patterns (___________________) • Width of rings can indicate growth conditions for tree (rainfall, etc.) • Can reconstruct climate information • Oldest reconstructions go back 8,000 yr B.C.

32. Uses of Growth Rings • 2) Climate patterns • Oldest reconstructions from bristlecone pine wood go back as far as ________ yr B.C.

33. Plant nutrition • Plants sophisticated: All they need is CO2, H2O, ________________ • Can make all amino acids, nucleic acids, carbohydrates, vitamins they need • Contrast __________: need essential amino acids, fatty acids, carbohydrates, vitamins, etc.

34. Plant nutrition • Plants need ____ essential elements • Macronutrients: make up >_____% of plant • C, H, O, P, K, N, S, Ca, Mg • “See hopkins car is an MG” • “C HOPKiNS Car is an Mg” • Of these, >____% plant dry weight is each of C,H,O,N,K (Chonk!)

35. Plant nutrition • Plants need ____ essential elements • Micronutrients: make up <_____% of plant dry weight. Need in tiny amounts! • Fe, Mo, B, Cu, Mn, Zn, Cl • “A festive mob comes in ___________” • “a Festive MoB CuMnZn CL___________”

36. Plant nutrition • All elements come to plant mostly from _____ • Except for C and some O, which come from atmosphere (CO2) • What usually limits plant growth? • ______! Why? • Lots needed for proteins, nucleic acids, etc. • Easily washed from soil

37. Plant nutrition • Nitrogen: lots in atmosphere (______% N2) • But plants can’t ______ that • Nitrogen fixation: bacteria use N2 to form NH3 (ammonia) or NO3- (nitrate)

38. Plant nutrition • Special ways to get N: • _____________: Leaves modified to trap and digest animals. Mainly to supplement N (bog soils low in N)

39. Plant nutrition • Special ways to get N: • ______________ bacteria: many legume plants form nodules on roots. N-fixing bacteria inhabit, obtain ____________, provide plant with N

40. Kingdom Animalia

41. Kingdom Animalia • About 1.2 million described species • Approx. ____% are arthropods (Phylum Arthropoda), most of those are insects (Class Insecta) • Contains about _______ phyla, most of which are marine (where life ________)

42. Kingdom Animalia • Evolved from Protista

43. Major features of animals • 1) _______________ • 2) _______________ • 3) Lack _____________. Most have tissues: organized groups of cells specialized to perform specific functions • 4) Move in rapid and complex ways. Flexible cells, presence of nerves and muscles. • 5) ___________ meiosis. Make eggs and sperm.

44. Major features of animals • 6) Embryo stage. • Morula: Solid ball of cells • Becomes a ______________: Hollow ball of cells • Then becomes Gastrula: Hollow ball with a sac at one end (called _______________)