Roots

Question 1

main function of roots

Answer 1

1. anchorage: stability, proper orientation
2. absorption: w/ cylindrical shape that has an ideal surface-volume ratio
3. hormone production: produce cytokinin & gibberellin imported to
   the shoot system

Question 2

two classifications of root system based on origin

Answer 2

1. taproot system
2. fibrous root system

Question 3

taproot system is derived from an embryonic root called ____. example: radish, carrots, etc.

Answer 3

radicle

Question 4

the emerging branching of a taproot system is ___ while its primary root grows ____.

Answer 4

lateral; downward

Question 5

taproot system is common to ____.

Answer 5

eudicots

Question 6

dense, fine network of roots that arises when radicle dies during or immediately after germination

Answer 6

fibrous root system

Question 7

fibrous root system grows ____ and is common to ____.

Answer 7

horizontally; monocots

Question 8

fibrous root system forms roots that develop outside the root system. what is this called?

Answer 8

adventitious roots

Question 9

external structures of individual roots

Answer 9

1. root tip
2. root cap
3. root hairs
4. rhizodermis/epiblem

Question 10

a root’s external structure that refers to the extreme tip pushing thru the soil

Answer 10

root tip

Question 11

a root’s external structure that protects the root apical meristem and is formed by terminal _____ cells. this structure constantly worn away and must be renewed.

Answer 11

root cap; parenchyma

Question 12

the root cap provides lubrication to the root tip as they grow downwards (glycoprotein + pectin)

Answer 12

true

Question 13

dictyosomes of root cap cells secrete this polysaccharide for lubrication

Answer 13

mucigel

Question 14

a root’s external structure that provides increased surface area for absorption

Answer 14

root hairs

Question 15

root epidermis with root hairs that also produces mucigel and never develops cuticle

Answer 15

rhizodermis/epiblem

Question 16

the rhizodermis/epiblem has stomata. true or false?

Answer 16

false

Question 17

rhizodermis is different from root pericycle. true or false?

Answer 17

true

Question 18

rhizodermal cells that give rise to root hairs

Answer 18

trichoblasts

Question 19

cells that do not produce root hairs

Answer 19

atrichoblasts

Question 20

internal structures of roots: longitudinal section

Answer 20

1. root cap
2. zone of division
   
   1. root apical meristem
   2. quiescent zone
3. zone of elongation
4. zone of maturation
   
   • root hair zone
   • zone of primary permanent tissues
   • zone of secondary permanent tissues

Question 21

cells in the central portion divide, and the root cap grows forward. on the edges, cells divide and expand in such a way that the cells flow radially outward. true or false?

Answer 21

true

Question 22

site of gravisensing found at the center of the root cap containing ____.

Answer 22

columella; amyloplasts

Question 23

amyloplasts of columella cells

Answer 23

statoliths

Question 24

statolith-containing cells of columella cells

Answer 24

statocysts

Question 25

located at the apex of the root proper but is buried under the root cap

Answer 25

root apical meristem

Question 26

cells produced in the RAM id more orderly than those produced in SAM. true or false?

Answer 26

true

Question 27

do all cells undergo cell division?

Answer 27

no, some are in quiescent stage

Question 28

mitotically inactive central region where cells are resistant to various types of harmful agents and act primarily as a reserve of healthy cells

Answer 28

quiescent center

Question 29

are nuclei in the quiescent center radioactive?

Answer 29

no

Question 30

where most cells continue to enlarge; cells begin to differentiate into a visible pattern

Answer 30

zone of elongation

Question 31

zone of elongation differentiation: protoderm: ___ procambium: ___ ground meristem: ___

Answer 31

rhizodermis vascular cylinder root cortex

Question 32

tissues in the zone of elongation are all ___.

Answer 32

permeable

Question 33

where several processes occur more or less simultaneously: * root hairs grow outward * thin cuticle appears to be present in some micrograph * cortex continues to enlarge; able to transfer minerals from epidermis to the vascular tissues

Answer 33

zone of maturation

Question 34

internal structure of roots: cross section

Answer 34

1. rhizodermis 2. cortex 3. endodermis 4. pericycle 5. stele (vascular cylinder)

Question 35

the outermost region of a root's cross section

Answer 35

rhizodermis

Question 36

ground tissues between rhizodermis and vascular tissues derived from ____.

Answer 36

root cortex; ground meristem

Question 37

innermost cortical layer with casparian strip

Answer 37

endodermis

Question 38

in the zone of maturation, minerals do not have a free access to the vascular tissues due to endodermis. true or false?

Answer 38

true

Question 39

fuunction of casparian strip

Answer 39

controls the types of minerals that enter the vascular tissues

Question 40

casparian strip is made up of what components?

Answer 40

lignin suberin

Question 41

four routes in transporting materials from root hairs to vascular tissues

Answer 41

1. apoplastic route 2. symplastic route 3. transmembrane route 4. endodermal route

Question 42

describe apoplastic route

Answer 42

thru cell wall

Question 43

describe symplastic route

Answer 43

thru plasmodesmata

Question 44

describe transmembrane route

Answer 44

from the apoplastic route to the protoplasm via symplast

Question 45

describe endodermal route

Answer 45

casparian strip blocks passage of water and minerals; mineral in symplast/entering the pathway by crossing the plasma membrane of an endodermal cell can pass

Question 46

parenchyma cells between endodermis and vascular tissues; gives rise to lateral roots

Answer 46

pericyclela

Question 47

lateral roots (pericycle) are derived endogenously which means what?

Answer 47

they are derived from the root interiors/deep within the roots

Question 48

the central vascular cylinder of the root

Answer 48

stele

Question 49

stele is bound by the ___ to the exterior.

Answer 49

endodermis

Question 50

stele contains what components?

Answer 50

xylem phloem some parenchyma pericycle

Question 51

describe a eudicot stele

Answer 51

xylem form a solid mass at the center surrounded by phloem

Question 52

eudicot stele has a pith. true or false?

Answer 52

false. it has no pith

Question 53

inner wide cells in eudicot stele

Answer 53

metaxylem

Question 54

outer narrow cells in eudicot stele

Answer 54

protoxylem

Question 55

phloem occurring outside the eudicot stele

Answer 55

protophloem

Question 56

phloem occurring inside the eudicot stele

Answer 56

metaphloem

Question 57

describe monocot stele

Answer 57

strand of xylem and phloem are scattered in the ground tissues = atactostele

Question 58

type of roots based on support

Answer 58

1. buttress: plate-like and brace the trunk against being blown over by wind; rubber trees 2. brace: thrives in intertidal marshes and strong currents; provides stability; mangrove; ex: rhizophoraceae 3. prop roots: provide support and help aerate those in low o2 substrate; observed in monocots; ex: pandanaceae 4. clinging roots: roots spread along the surface of the bark; ex: orchid 5. strangling/drop roots: roots cling to the bark of host tree and grow rapidly downward; ex: strangler fig

Question 59

type of roots based on storage

Answer 59

1. food storage: manihot esculenta 2. water storage: desert plants; ex: turbinicarpus 3. contractile roots: plants with bulbs; ex: hyacinthus ep. 4. nodular roots: legumes; ex: pea roots

Question 60

modified roots for protection may possess ___ to deter herbivores

Answer 60

spines

Question 61

modified roots for aeration allow root to perform ___; common in pneumatophores of mangroves

Answer 61

gas exchange

Question 62

modified roots for photosynthesis have _____ capable of photosynthesis; common in aerial roots of orchids; ex: taeniophyllum (orchidaceae)

Answer 62

chlorophyllous

Question 63

modified roots for reproduction have ___ roots that give rise to another plant; ex: kalanchoe; kataka-taka

Answer 63

adventitious

Question 64

plants that cling to rocks

Answer 64

lithophyte

Question 65

plants found in branches/trunk

Answer 65

epiphyte

Question 66

underground storage organs of plants

Answer 66

bulb