Secondary Growth Secondary Growth Two types of growth

Secondary Growth

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

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

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.

Secondary Growth • Stem cross section

Secondary Growth • Vascular bundles contain _________ • Located between primary xylem and phloem • Meristematic: can still do ________

Secondary Growth • Residual procambium cells start to divide • Produce new cells _______

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

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

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

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) ______

Secondary Growth • Two

Secondary Growth • Later secondary growth

Secondary Growth • First cork cambium: Forms under ______

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

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 _______.

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

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

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

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)

Secondary Growth • Ex, oak (note vessels, thick-walled _____)

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?

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

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

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

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

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

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

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

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

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.

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

Plant nutrition • Plants sophisticated: All they need is CO 2, H 2 O, ________ • Can make all amino acids, nucleic acids, carbohydrates, vitamins they need • Contrast _____: need essential amino acids, fatty acids, carbohydrates, vitamins, etc.

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 HOPKi. NS Car is an Mg” Of these, >____% plant dry weight is each of C, H, O, N, K (Chonk!)

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 Mo. B Cu. Mn. Zn CL______”

Plant nutrition • All elements come to plant mostly from _____ • Except for C and some O, which come from atmosphere (CO 2) • What usually limits plant growth? • ______! Why? • Lots needed for proteins, nucleic acids, etc. • Easily washed from soil

Plant nutrition • Nitrogen: lots in atmosphere (______% N 2) • But plants can’t ______ that • Nitrogen fixation: bacteria use N 2 to form NH 3 (ammonia) or NO 3 - (nitrate)

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

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

Kingdom Animalia

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 ____)

Kingdom Animalia • Evolved from Protista

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.

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 ________)