Ch 35/36 Stem/ Root Flashcards
7 outer stem structures Herbaceous and function/what it is
- Bud - undeveloped embryonic shoots
- Terminal Bud - at tip of stem
- Axillary bud(lateral) - located in leaf axils
- Node - area where leaf is attached
- Internode - region between 2 nodes
- Stomata - present on Herbaceous stems for gas exchange
- Epidermis - on Herbaceous stems for protection as with leaves
3 stem functions
- Growth: produce new tissue
- Support: holds structures above-ground
- Transport: connect roots with tips of shoot system
5 Woody stem structures different than herbaceous
- Bud Scales - cover/protect dormant buds
- Bud Scale Scar - left where bud scale falls off when bud resumes growth
- Leaf Scar - where leaf was attached to stem
- Lenticels - sites of loosely arranged cells that allow Oxygen to diffuse into interior of Woody stem
- Periderm (outer bark) - replacement for epidermis on Woody stems
2 Internal stem structure arrangement: Herbaceous Eudicot
- vascular bundles arranged in circle
- distinct Cortex and Pith (primarily for storage)
3 Internal structure arrangement of Monocot (All Herbaceous) Stems
- Vascular bundles scattered in ground tissue
- NO distinct cortex/pith
- Primary Growth ONLY
In a Eudicot, what are the 2 major types of ground tissue in a Leaf?
Palisade
Spongy mesophyll
What is secondary growth, where/what type(mono/dicot/gymno/angiosperm) does it occur?
production of secondary tissues(wood/bark) through lateral meristems
- occurs in “Dicots” and Gymnosperms
2 areas of secondary growth and what do they produce
- Vascular Cambium: produces Secondary Xylem(wood) /Phloem(inner bark)
- Cork Cambium: produces periderm
Cork Cambium produces Periderm which includes what the outer bark which is______ and ______. what’s their use?
outer bark
- Cork Cells - replace epidermis in Woody
- Cork Parenchyma - storage
Xylem/ Phloem growth patterns in spring and summer. How might it be different in tropics or during drought?
Xylem
Spring: following dormancy, Large cells with Thin walls form for increase Water uptake
Summer: Small cells with Thick walls form for greater Strength
Phloem: crushed each year and Added to Bark
- what type of trees are associated with Hardwood and Soft wood
- what are 2 types of wood in a tree
Softwood: wood of Conifers - Lacks Vessel elements and fibers
Hardwood: wood of Angiosperms (not always literally hard)
Heartwood: in middle(heart) - as trunk’s girth increases, oldest xylem is filled with waste products(increase strength/pest resistance)
Sapwood: outer area. Functional Xylem
Xylem Transport(what it does in which direction and from where)
Water and dissolved minerals move upward from soil to root to stem to atmosphere
Phloem Transport(what it does in which direction and from where)
Sugar from leaves(made by photosynth.)
movement up and down and require energy from the plant
what is the most direct source of energy for xylem transport under normal conditions?
Sunlight
what hypothesis explains movement of materials in phloem
Pressure-Flow Hypothesis
What is Water Potential (W.P.)
a measure of tendency for osmosis to occur
i.e. measure of a cell’s ability to release/absorb water
how does water move and when will Osmosis occur (both considering W.P.)
water moves from regions of Higher W.P. to regions of Lower
- Osmosis will occur when W.P.s are Unequal
What 2 forces cause Xylem’s upward flow? Which is stronger?
pull of Transpiration(stronger) and Root Pressure
Why does Root Pressure occur
water moves into roots due to active absorption of mineral ions from soil
When might Guttation occur?
when soil is wet, and the difference in root and soil W.P. is great enough
What is the Predominant Sugar translocated in Phloem?
Sucrose
Describe phloem translocation of sugar. Is it faster or slower than Xylem trasnport?
dissolved sugar is moved up or down from a Leaf (source of excess sugar)
- to a Sink (area of storage or sugar use: Roots, apical meristems, fruits, seeds)
- Slower than xylem transport
In the Pressure-Flow Hypothesis, how is turgor pressure produced?
by water entering phloem at a source and leaving at a sink drives flow(in phloem)
which type of specialized stem is underground with fleshy leaves attached to a short stem?
Bulb
which type of specialized stem is a Horizontal underground stem
Rhizome
which type of specialized stem is a fleshy underground stem enlarged for food storage
Tuber
which type of specialized stem is short, erect, and underground covered by papery scales
Corm
which type of specialized stem is horizontal Above ground
Stolon
at the core of an Herbaceous Eudicot Stem is…
Pith
What is the Radical in a Taproot System?
embryonic root of a seed plant
what is a Taproot System?
common in monocots or eudicots?
has one main root formed from the radicle from which lateral root extend
common in eudicots
How is a Fibrous Root System
primary in monocots or eudicots?
has many Adventitious roots of same size developed from stems. Lateral roots branch from adventitious roots
primary in Monocots
Roots: Eudicots
3 primary tissues inside and what type of growth
- Epidermis
- Cortex (ground tissues)
- Stele (vascular tissues)
What is the Epidermis used for, what does it allow?
for protection but no cuticle allowing water absorption
Root hairs’ functions, where are they located
short-lived extensions of epidermal cells
- help absorb water and dissolved minerals
what happens that causes clay to be attracted to roots
roots secrete H+ (cations) which displace other positively charged mineral ions from soil particles, clay has negative charges on the outer surface
Eudicot Roots
- What is the Cortex mostly made of
- What is the innermost layer of the cortex called and what does it do?
mostly parenchyma cells(store starch)
- Endodermis: regulates movement of water/minerals into root xylem
Which of the 2 pathways of water/minerals through the epidermis and cortex…
- goes along interconnected cell walls, outside of cell membranes until reaches endodermis
- goes through cell’s interconnect cytoplasm and plasmodesmata, inside cells
- Apoplast
- Symplast
Stele (Vascular cylinder)
What gives rise to lateral roots and meristems
Pericycle
how is xylem and phloem in the root of eudicots
xylem forms solid core in the center (NO PITH)
looks like X
how is xylem and phloem in the Root of a Monocot
- what type of growth
alternate rings of xylem and phloem bundles surround center of PITH
- NO vascular cambium
- PRIMRY GROWTH, no secondary growth
