Plant Bio Exam 1 Flashcards
(164 cards)
1
Q
Herbaceous tissue of the primary plant body develops from the what?
A
apical meristem
2
Q
Vascular tissues occurs in what in the stem?
A
distinct bundles
3
Q
In woody species, what are produced in the stem & root from activity of other meristems?
A
secondary tissues
4
Q
produces wood containing secondary xylem
A
vascular cambium
5
Q
produces bark containing secondary phloem and cork
A
cork cambium
6
Q
Vascular cambium and cork cambium constitute the plants what?
A
secondary body
7
Q
Woody plants are a combination of what?
A
primary and secondary tissue
8
Q
A herbaceous plant’s conducting capacity is set after what?
A
a portion of stem or root is mature
9
Q
Woody plants become wider every year by what?
A
accumulation of wood and bark, giving them a greater conducting capacity
10
Q
Disadvantages to secondary growth (being woody)
A
- greater need for defenses, both structural and chemical to survive for a long time
- must use energy & nutrient resources for winterizing their bodies in temperate climates
- expensive metabolically to construct wood and bark
- Woody plants may not reproduce until they are several years old due to the energy spent on other activities
11
Q
All woody trees and shrubs (including gymnosperms) descended from one group of what?
A
ancestral woody plants that arose about 370 million years ago
- therefore ‘Wood’ is an ancient trait and has evolved infrequently
12
Q
Most evidence indicates that the first flowering plants were what?
A
woody
13
Q
What is the derived condition of the herbaceous condition?
A
loss of wood
14
Q
True secondary growth (wood) occurs in what?
A
- many eudicots
- most basal angiosperms
- all gymnosperms
- but never in ferns or monocots
15
Q
What initially evolved from a woody ancestor but later lost the ability to produce woody tissues?
A
monocots
16
Q
the meristem that produces the wood of the secondary plant body
A
Vascular cambium
17
Q
-It originates as a layer of cell that lies between the xylem
and phloem of a vascular bundle in a plant stem
- In herbaceous plants these cells do not divide (usually)
- But in woody plants this region becomes meristematic
A
Vascular cambium
18
Q
occur between xylem and phloem within a vascular bundle
A
Fascicular cells
19
Q
occur between vascular bundles
A
Interfascicular cells
20
Q
To form a complete vascular cambium that completely encircles the plant stem, what two region of cells must become meristematic?
A
1) Fascicular cells
2) Interfascicular cells
21
Q
Once developed, the vascular cambium will consist of what?
A
a single cell layer encircling the stem that is capable of continued division
22
Q
What two types of cells does the vascular cambium contain?
A
1) Fusiform initials
2) Ray initials
23
Q
long and narrow vascular cambium cells
A
fusiform initials
24
Q
short, cuboid vascular cambium cells
A
Ray initials
25
- long, tapered cells
- divide to produce (to the interior) the elongate cells of xylem (wood): tracheids, vessel elements, fibers, parenchyma
- also divide to produce (to the exterior) elongate cells of phloem: sieve cells, sieve tube members, companion cells, fibers, parenchyma
Fusiform initials
26
Fusiform initials of the vascular cambium divide longitudinally with what to produce two elongate cells?
periclinal wall (parallel to the meristem)
- one cell remains a fusiform initial (of the meristem)
- the other differentiates into either a cell of secondary xylem or secondary phloem
27
What (produced to the interior) increases greatly in diameter in growth, pushing the vascular cambia cells outward?
Secondary xylem cells
- produces stress on the cambial cells that can't keep up
28
Vascular cambium cells must occasionally divide longitudinally by what (perpendicular to the cambium's surface)?
anticlinal walls
- allows the cambium to add cells and increase in diameter and keep up with the increasing girth of the woody layer underneath
29
- short and cube-shaped
- divide to form xylem or phloem parenchyma that functions in storage or as albuminous cells (in gymnosperms)
Ray initials
30
Within the vascular cambium, Fusiform initials may occur (depending on the tree species):
- in regular horizontal rows (storied cambium)
- irregularly, w/o any horizontal pattern (nonstoried cambium)
31
Within the vascular cambium, Ray initials are grouped together in what?
short vertical rows
- one cell wide (uniseriate)
- two cells wide (biseriate)
- many cells wide (multiseriate)
32
Vascular cambium never has what?
large regions of just fusiform initials or just ray initials; it is always mixed
33
The overall ratio of fusiform initials to ray initials for a species is what?
relatively constant
- under precise genetic/developmental control
34
Types of wood cells:
- secondary xylem (wood)
- an axial (vertical) system
- a radial (horizontal) system
35
contains all of the cell types that occur in primary xylem
Secondary xylem (wood)
36
derived from fusiform initials
Axial (vertical) systems
37
develops from the ray initials
radial (horizontal) system
38
The axial system contains what?
- Tracheary elements
- fibers
- parenchyma
39
tracheids and vessels that carry out vertical conduction of water through the wood
Tracheary elements
40
provide strength
fibers
41
serves as a temporary reservoir of water
parenchyma
42
Hardwoods vs softwoods
- Hardwoods contain large amounts of fibers
- Softwoods contain few or no fibers
43
Most gymnosperms (softwoods) contain only what?
tracheids in their axial systems
- fibers and parenchyma cells are sparse or absent
44
In woody angiosperms, the radial system ('rays') contains only what?
parenchyma
- arranged in uniserate, biseriate, or multiseriate arrays-
45
For woody plants in temperate regions: Where do growth rings occur?
in wood due to the differential growth of early (spring) wood versus late (summer) wood
46
what has high proportions of wide vessels or tracheids?
spring wood
47
what has fewer vessels or narrower, thick-walled tracheids?
summer wood
48
What makes up 1 year's growth, or annual (growth) ring?
Early wood and late wood
49
wood with vessels found mostly in early wood
ring porous
50
Ring porous species include:
- oaks
- hickories
- ashes
51
wood with vessels found throughout
diffuse porous
52
diffuse porous species include
- red maple
- black gum
53
- center of a log
- darker, drier, andmore fragrant
heartwood
54
-outer log
- light colored
Sapwood
55
- denser
- contains less water
- more aromatic
- better acoustic properties
Heartwood
56
Heartwood forms when:
- tracheary elements of older portions of wood no longer function in water transport
- tree seals off this old vascular tissue in the wood to avoid fungal hyphae or bacteria from invading and causing rot
57
What forms inside the old tracheary elements?
tylosis
58
intruding plug from an adjacent (living) parenchyma cell
tylosis
59
What produces compounds that inhibit growth of bacteria and fungi?
Xylem parenchyma cells (XP)
- makes cells dark and aromatic
60
Eventually, the tracheary elements are completely plugged up and filled with what?
defense compounds
61
When the parenchyma cells die (in heartwood), they leave behind what?
dark, highly decay-resistant cells
62
What contributes to heartwood?
parenchyma and tracheary elements
63
In laterally spreading branches, what is necessary to provide support? What is the resulting wood called?
- differential wood strength
- reaction wood
64
In angiosperms, additional growth occurs mostly on which side of a branch?
upper side; tension wood (pulling up)
65
- enriched with gelatinous fibers enriched with cellulose
- grows on upper side of a branch
- thicker annual rings on top of branch provide additional strength
- thinner annual rings occur on bottom of branch
Tension wood
66
Conifers from reaction wood enriched with lignin on what side of the branch?
underside; compression wood (pushing down)
67
- thinner annual rings occur on top of branch
- thicker annual rings on bottom of branch provide additional strength
- enriched with lignin
Compression wood
68
Many types of wood are prized for their what?
color, density, or acoustic properties
69
$70/board foot
african blackwood
70
$100/board foot
Black wood Ebony
71
$12/board foot
Sandalwood
72
$15/board foot
Black walnut
73
$4-6/ board foot
Red oak
74
What is responsible for conduction up and down the stem (or root) by the secondary xylem and phloem?
axial system
75
What are formed just the same as xylem rays? They are formed by the same cuboid initials in the vascular cambium
horizontal rays into phloem
- rays consists of parenchyma storage cells
76
What usually conducts for less than 1 year?
Sieve tube members and sieve cells of the secondary phloem
77
Which layer is capable of conduction?
Only the innermost, newest layer of phloem
78
The functioning phloem in a woody stem is what?
a narrow layer adjacent to the vascular cambium, and is always the most recent (youngest) layer produced
79
As secondary tissues are added and pushed outward, tissues on the periphery either:
- grow in circumference
- are torn apart and collapse
80
As circumferential stretching increases and older sieve elements die, some storage parenchyma cells of the phloem what?
are activated and undergo cell division
- this activity results in a new cambium meristem arising from within the old secondary phloem (cork cambium or phellogen)
81
After each division, the inner cell remains _ while the outer cell differentiates into _?
cork cambium; cork (phellem) cell
82
Vascular cambium is what?
bifacial
- secondary xylem to the inside
- secondary phloem to the outside
83
Cork cambium is what?
unifacial (usually)
- cork to the outside
84
In a few species, the cork cambium may produce some tissue to the inside to form a parenchyma layer known as what?
phelloderm
85
The layers of cork cells (and the phelloderm, if present) are called what?
periderm
86
The cortex is a mixture of what?
original cells of the cortex, older secondary phloem, and primary phloem all scrunched to the exterior of the stem cylinder
87
The cork cambium is what?
irregular and not fixed in place
88
New cork cambium forms where?
in younger secondary phloem closer to the vascular cambium
- this continually produces new bark tissues from layers underneath the surface, as older tissues are pushed outward
89
All tissues of a woody stem that is exterior to the vascular cambium
bark
90
secondary phloem part of bark
inner bark
91
the dead, cork tissue produced by the cork cambium
outer bark
92
Cork cells become filled with what and then die?
waxy suberin and defene compounds
93
What makes the periderm waterproof and chemically inert?
the waxy suberin and defense compounds in cork cells
- great protection from herbivores and xylovores (wood eaters)
94
Building materials and textiles made of bark
- bark shingle siding
- mulch
- tanning hides
- cloth
- canoes
- ropes
- cork
- substrate for paintings and maps
95
Medicinals, flavorings, and drugs made of bark:
- spices: cinnamon
- hallucinogens: Ayahuasca
- Medicines:
-- willow = aspirin
-- birch = anti-tumor
-- Pacific Yew = taxol
96
- process of removing the outermost layers of a woody stem in a ring
- traditional method of killing trees without felling them
Girdling
97
What does girdling remove?
- periderm (cork layer)
- cork cambium
- secondary phloem layers
- vascular cambium
- sometimes sap wood
98
Complete girdling means phloem is completely removed leading to
starvation and death of the upper tree portions
99
Downside of cork:
impermeability of cork blocks the absorption of oxygen, preventing respiration of internal tissues
100
Bark becomes permeable to oxygen when what?
special rounded cork cells are produced
- allows air spaces to develop between the outer layers of cork
- 'lenticels'
101
What creates an astounding diversity of tree bark?
differences in cork cambium activity and patterns of shedding of older outer bark
102
What are the four main functions of roots?
1. anchoring the plant firmly to a substrate
2. absorbing water and minerals from soil
3. producing hormones
4. Storing carbohydrates in the winter
103
Most eudicots have what?
taproots
104
a single large root that develops from the radicle
taproots
105
what are initially produced from the taproot?
Lateral roots
106
Later, what may also produce more lateral roots, resulting in a highly branched root system?
Lateral roots
107
Most monocots have what?
a fibrous root system
108
- mass of many similarly sized major roots near the soil surface
- each giving rise to smaller lateral roots
- the major roots are "adventitious", arising in development from stem tissue
fibrous root system
109
Major roots do not arise from what?
the radicle (as in tap-rooted plants)
110
Roots grow from what?
an apical meristem at the root tip
111
The initial apical meristem was a part of what?
the embryo in the seed
112
The root apical meristem is protected by what?
a root cap
113
Just behind the root cap and root apical meristem is the what?
zone of elongation
114
Cells in this region undergo expansion
zone of elongation
115
A region in which many of the epidermal cells extend out as narrow trichomes
- greatly increase the root's surface area and absorbing capacity
root hair zone
116
New lateral roots emerge from what?
the primary tap root from behind the root hair zone
117
- a protective structure produced by the underlying meristem
- continually being worn away due to abrasion during growth through soil, so it continuously needs to be replaced
root cap
118
cells of the root cap contain large starch granules that sink to the bottom of the cell called
statoliths
119
What influences the flow of the hormone auxin upward in the root?
position and distribution of statoliths
120
For a root extending horizontally, the statoliths cause what?
an increase in auxin on the underside of the root
- this decreases cell elongation on the underside
- cell elongation increases on the upper surface
- net effect: bending of the root tip downward
121
Root cap cells secrete copious amounts of what?
mucigel
122
a complex polysaccharide rich in carbohydrates and amino acids
mucigel
123
- lubricates passage of the root through the soil
- chemically causes soil to release nutrients
- fosters rapid growth of beneficial soil bacteria, which further help in uptake of nutrients
Mucigel
124
zone around the root tip of a plant constitutes the
rhizosphere
125
three zones of root apical meristem
1. zone that yields new root cap cells
2. a quiescent center
3. upper zone that yields the cells of the growing root
126
region of the root beyond the meristematic region
- cells are enlarging, but not fully mature yet
- epidermal, vascular tissue & cortex regions begin to differentiate
zone of elongation
127
zone of maturation is marked by what?
1. the production of root hairs growing by the epidermal cells
2. differentiation of tissues
- root cortex cells transfer water & minerals from the epidermis to the vascular region (eudicot e.g.)
128
cell to cell through shared cytoplasm connected by plasmodesma
symplastic
129
transport on the exterior of cells along the cell walls
apoplastic
130
transport of water through the cortex may be
symplastic or apoplastic
131
- is one cell layer thick ad is the inner-most layer of cortex
- marks the boundary between the cortex and vascular region
- radial cell walls are rich in waterproof lignin and suberin; these constitute the Casparian strip
Endodermis
132
tightly controls the flow of water and minerals that may pass through the vascular tissue
Casparian strips
133
How do casparian strips control flow?
by cutting off the apoplastic pathway, forcing symplastic transport of water and minerals
134
Materials can only pass to vascular tissues _
symplastically
135
The casparian strip forces what?
symplastic flow
136
Casparian strip options
1. apoplastic flow is blocked
2. apoplast to symplast
3. symplastic flow
137
- irregular cylinder of parenchyma cells lying underneath the endodermis
- capable of becoming meristematic and giving rise to lateral roots
Pericycle
138
- this is the central cylinder of tissue, interior to the endodermis
- consists of pericycle, xylem, and phloem
- xylem is in the center
- phloem is outside of the xylem
- no pith in eudicots
Vascular stele
139
Within the xylem
- inner widest cells are metaxylem (produced last)
- outer narrow cells are protoxylem (produced first)
140
Within phloem regions
- protophloem occurs on outer side
- metaphloem occurs on inner side
141
the arrangement of tissue within the stele differs for what?
monocots
142
Arrangement of tissue within the stele for monocots
- large vessels and distinct bundles of phloem occur scattered throughout the region, interior to the endodermis
- plus there's a central pith region
143
Mature portions of the root
- root hairs have withered away
- the endodermis deposits suberin and lignin over the radial and tangential surfaces of the casparian strip forming a completely sealed cylinder
- this blocks all symplastic and anoplastic flow into the stele
- water and minerals can therefore only enter into the cylinder from younger portions of the root
144
eventually lateral roots emerge:
a group of cells of the pericycle divide to form a root primordium and organize into a root apical meristem
145
By the time the lateral root emerges
- it has formed a root cap
- first protoxylem and protophloem of the vascular stele have begun to differentiate
- this establishes a direct connection between the lateral root to the vascular tissues of the parent root
146
Above the maturation zone, in the older parts of the root, big changes happen
1) Root hairs whither away
2) secondary cambia emerge to produce wood and bark of the root, just as in the stem
147
Vascular cambium ->
root wood
148
Cork cambium ->
root bark
149
The root vascular cambium arises within what?
the stele when parenchyma (btw xylem and phloem) and a few pericycle cells join together to form the meristem
150
The cambium is initially what?
irregular in shape (undulating) and positions the phloem to the exterior
151
As the root vascular cambium begins producing columns of cells, its outline becomes what?
more regularly circular
152
As in stems, the root vascular cambium produces what?
- secondary xylem to the inside (OG primary xylem remains in center)
- secondary phloem to the outside (OG primary phloem gets pushed to the exterior)
153
Bark on roots is produced by what?
cork cambium (phellogen) that arisesin the pericycle
154
Production of cork cell on the exterior of the cork cambium ultimately causes what to shed?
old endodermis, cortex, and epidermis
155
Most woody roots have what?
high storage capacity
156
storage occurs in what cells of the root?
parenchyma
157
storage occurs in parenchyma cells of the root found in:
1. Ray parenchyma cells (horizontal)
2. Axial parenchyma cells (vertical)
- both are products of the root vascular cambium
158
The wood of a root is different than the wood of a stem in that:
1. It is mostly parenchyma
2. there are few vessels and no fibers
- this wood is therefore well adapted for long-term storage
159
Root parenchyma stores what?
1. carbohydrates
2. water
3. proteins
160
Storing materials in the roots have many advantages, including:
1. roots are less visible as food for most foragers
2. Root surroundings are more stable and protected from environmental fluctuations than aboveground parts
161
for crops like carrots and radishes, the taproot that we consume is secondary growth (wood) modified for high capacity storage
Storage taproots
162
- tall plate-like roots of some tropical trees
- upper side grows more rapidly than other parts of the root
- brace the trunk from being blown over by wind or in thin soils
Buttress roots
163
aerial roots of orchids have a specialized epidermis layer called a what?
Velamen; Velamen roots of epiphytes
164
What prevents water loss in dry conditions of orchids?
velamen
