roots Flashcards
1
Q
- Anchoring the plant firmly to a substrate (soil)
- Absorption of water and minerals
- Production of hormones.
• shoot growth and development depend on the hormones cytokinin and gibberellin
A
Main Functions of Roots
2
Q
shoot growth and development depend on the hormones __________ and ______________
A
cytokinin, gibberellin
3
Q
cytokinin and gibberellin
A
Shoot system
4
Q
3 main tissues
A
Dermal
Ground
Vascular
5
Q
• Carbohydrate storage - Fleshy taproots (i.e. carrots, beets, radishes)
• Protection – in Crysophila and Mauritia, roots grow out of the trunk and harden into sharp spines
• Vegetative reproduction – roots spread horizontally and produce shoot buds (i.e. willows, sorrel)
• Parasitic roots - modified roots attack other plants and draw water and nutrients out of them (i.e. mistletoe, dodder)
A
Additional / Specialized Function
6
Q
Fleshy taproots (i.e. carrots, beets, radishes)
A
Carbohydrate storage
7
Q
SN of carrots
A
Daucus carota
8
Q
SN of beets
A
Beta vulgaris
9
Q
SN of radishes
A
Raphanus satidus
10
Q
in Crysophila and Mauritia, roots grow out of the trunk and harden into sharp spines
A
Protection
11
Q
roots spread horizontally and produce shoot buds (i.e. willows, sorrel)
A
Vegetative reproduction
12
Q
modified roots attack other plants and draw water and nutrients out of them (i.e. mistletoe, dodder)
A
Parasitic roots
13
Q
Three types of root system:
A
- TapRoot
- FibrousRoot
- Adventitious
14
Q
• single prominent root (tap root) that is much larger than all the rest and numerous small roots (lateral roots or branch roots) coming out of it
A
Tap Root
15
Q
Derived from the radicle (embryonic root)
A
Tap Root
16
Q
Derived from the radicle (embryonic root)
A
Tap Root
17
Q
Anchorage
A
Tap Root
18
Q
Common in dicot and gymnosperm
A
Tap Root
19
Q
perennial and woody plants: roots undergo secondary growth
A
Tap Root
20
Q
perennial and woody plants: roots undergo secondary growth
A
Tap Root
21
Q
carrots, beets, radish, turnips
A
Fleshy taproots
22
Q
turnips sn
A
Brassica rapa
23
Q
sweet potatoes, cassava
A
Swollen lateral roots
24
Q
SN of sweet potatoes
A
Ipomoea batatas
25
SN of cassava
Manihot esculenta
26
taproot is about the carrot same size as the laterals
Sunflower
27
SN of Sunflower
Helianthus annuus
28
mass of many similarly sized, delicate and hair-like roots
Fibrous Root
29
no prominent enlarged primary root
Fibrous Root
30
Produced after death of radicle
Fibrous Root
31
Derived from the root primordia found at the end of radicle
Fibrous Root
32
Common in monocots and some dicots
Fibrous Root
33
Absorption
Fibrous Root
34
• mass of many similarly sized, delicate and hair-like roots
• no prominent enlarged primary root
• Produced after death of radicle
• Derived from the root primordia found at the end of radicle
• Common in monocots and some dicots
• Absorption
Fibrous Root
35
• Do not arise from pre-existing roots
• Present in monocot and dicot
* brace root - arise from main trunk stem
* prop root - arise from the lateral
branches of the main stem.
Adventitious Root
36
Do not arise from pre-existing roots
Adventitious Root
37
Present in monocot and dicot
Adventitious Root
38
arise from main trunk stem
brace root
39
arise from the lateral branches of the main stem
prop root
40
Secondary growth = ↑ quantity of healthy, functional wood (xylem) in the roots = ↑ no. of leaves and fine absorptive roots
Dicot Roots
41
secondary xylem and phloem
Dicot Roots
42
No secondary growth = stem of an older plant is not wider than young plant, no ↑ conducting capacity, no more leaves or roots than young plant
Monocot Roots
43
no secondary xylem and phloem
Monocot Roots
44
• Stolons or rhizomes = ↑ size
Monocot Roots
45
Stolons
horizontal stem above the ground
46
rhizomes
horizontal stem below the ground
47
horizontal shoots branch and then produce adventitious roots
Monocot Roots
48
Vegetative reproduction
Monocot Roots
49
the growing portion protected by root cap; push through the soil
Root tip
50
Thick layer of cells that protects root apical meristem (root tip); constantly being worn away and renewed
Root cap
51
complex polysaccharide secreted by dictyosomes of root cap for lubrication
Mucigel (Slime)
52
• found behind the root cap
and root apical meristem
• few mm long
• where cells undergo division
and expansion
Zone of elongation
53
• single celled extension of
epidermal cells which
increase absorptive area
• no line of demarcation in the
epidermal cells
• transitory(die within 4-5 days)
• form only in a part of the
root that is not elongating
Root hairs
54
• Cells are meristematic (cell division with transverse walls & forming files of cells that are pushed forward)
• As cells are pushed forward, they develop dense starch grains and their endoplasmic reticulum becomes displaced to the forward end of the cell = detects gravity because the starch grains settle to the lower side of the cell
Root Cap
55
Cells are meristematic (cell division with transverse walls & forming files of cells that are pushed forward)
Root Cap
56
As cells are pushed forward, they develop dense starch grains and their endoplasmic reticulum becomes displaced to the forward end of the cell = detects gravity because the starch grains settle to the lower side of the cell
Root Cap
57
• more orderly than the shoot because it experiences no disruptions
• Quiescent center - mitotically inactive central region
— cells are more resistant to various types of harmful agents such as radiation and toxic chemicals
— Serves as reserve of healthy cells
Root Apical Meristem
58
more orderly than the shoot because it experiences no disruptions
Root Apical Meristem
59
mitotically inactive central region
Quiescent center
60
Becomes active when root apical meristem or root cap is damaged and forms new ________
apical meristem
61
Once the new meristem is established, its central cells become inactive, forming a new _____________
quiescent center
62
the region where the cells expand greatly; some meristematic, but mostly enlarging
Zone of Elongation
63
outermost; forms epidermis (dermal region)
Protoderm
64
at center; forms primary xylem/ phloem then metaxylem/ metaphloem (Stele/ vascular region)
Provascular tissue
65
between protoderm and provascular tissue; Parenchyma cells that form root cortex
Ground tissue
66
• Root hairs grow outward
• zone of elongation merges gradually with the zone of maturation
Zone of Maturation
67
transfer of minerals from the epidermis to the vascular tissue
Cortex
68
diffusion through the walls and intercellular spaces
apoplastic transport
69
absorption into the cytoplasm of a cortical cell and then transfer from cell to cell through plasmodesmata
symplastic transport
70
1 – apoplastic
2 – apoplastic + symplastic
3 – symplastic
Cortex
71
Minerals do not have free access to the vascular tissues because the innermost layer of cortical cells differentiates into a cylinder called the ________
endodermis
72
• Controls the passage of minerals across the vascular tissues
• Consist of thick-walled cells (encrusted with suberin and lignin); diffusion is inhibited
Endodermis
73
• bands of lignin and suberin on the radial walls (top, bottom and side walls) causing the cell walls to be water proof
• Impermeable
• minerals can cross the endodermis only if the endodermal protoplasts absorb them, then secrete them into the vascular tissues
Casparian strip
74
1 – apoplastic (no apoplastic across the endodermis)
2 – apoplastic + symplastic
3 – symplastic
Casparian strip
75
Internal anatomy of young dicot root shows three general sections:
1. Dermal region
2. Cortex
3. Stele or vascular cylinder
76
epidermis with root hairs
Dermal region
77
outer collenchyma
middle parenchyma
inner endodermis
Cortex
78
xylem forms a solid mass in the center, surrounded by strands of phloem; no pith
Dicot
79
strands of xylem and phloem are distributed in ground tissue
Monocot
80
inner wide cells
Metaxylem
81
outer narrow cells
Protoxylem
82
Two to four or more groups of protoxylem may be present (larger roots = ↑ no.)
Dicot ( Triarch, Tetrarch, Pentarch )
83
many xylem poles
Polyarch
84
strands of xylem and phloem surrounding a parenchymatous pith
Siphonostele
85
most dicots
Vascular Tissue
86
found on the outer side
Protophloem
87
found on the inner side
Metaphloem
88
• Found between the vascular tissue and the endodermis
• parenchyma cells that constitute an irregular region
• Where growth of lateral roots are initiated
Pericycle
89
• Initiated by cell divisions in the pericycle
• Localized cells remains mitotically active creating a small root primordium that become a root apical meristem and pushes outward
• As it pushes outward, the new lateral root destroys the cells of the cortex and epidermis that lie in its path, ultimately breaking the endodermis.
• Then, formation of a root cap, first protoxylem and protophloem elements connected to the vascular tissues of the parent root.
Origin Development of Lateral Roots
90
Old dicot root shows two distinct regions:
1. Region of secondary vascular
2. Region of periderm layers
91
Region of secondary vascular tissues which include the
a. secondary phloem
b. vascular cambium
c. secondary xylem
92
Region of periderm layers:
a. phellem (cork)
b. phellogen (cork cambium)
c. phelloderm (cork parenchyma)
93
provide long-term storage for carbohydrates that accumulate during summer photosynthesis
Storage Roots
94
carrots, ube, radish, turnips
Fleshy taproots
95
SN of ube
Discorea alata
96
• Adventitious roots from stems
• Pandanus (screwpine), Ficus (Banyan trees)
Prop roots
97
in corn plant – for additional support and absorption
Brace roots
98
water retention; in aerial roots of orchids
Velamen
99
dead cells, white; acts as
water proof barrier
Velamen
100
Chlorophyllous roots
Photosynthesis
101
Movement; of bulbs like onions, gladiolus, garlic
Contractile roots
102
due to change in shape of cortical cells
Contraction
103
for absorption
Parasitic (haustorial roots)
104
diffuse root system
i.e Tristerix
Haustorium
105
tall, plate-like, expanded roots for great support
Buttresses
106
breathing roots of mangrove for aeration
Pneumatophores
107
With lenticels and aerenchyma for diffusion of Oxygen
Pneumatophores
108
nitrogen fixation
Root nodules
109
chemical conversion of atmospheric nitrogen into usable forms. Ex. ammonia, nitrates
nitrogen fixation
110
bacteria, fill host cells with bacteroids w/c convert N2 to nitrogenous compds
Rhizobium
111
formed by mitosis of cortical cells
Root nodules
112
Spiny roots of tugue
Protection
113
• Birds deposit seeds on the branch of a host tree
• When the seed germinates, the roots cling to the bark of the host tree, grow, hugging the host tree until it reach the soil.
Strangler Figs
114
association between a soil fungus (fungal hyphae) and roots
Mycorrhizae
115
Plant can absorb ________ effectively through mycorrhizae than roots hairs
phosphorus
116
small structure formed by fungi; filled with P
Arbuscule
117
hyphae penetrate between the outermost root cortex cells but never invade the cells
ectomycorrhizal relationship
118
hyphae penetrate the root cortex as far as the endodermis; but cannot pass the Casparian strip
endomycorrhizal
