Roots

Question 1

Three (3) functions of roots

Answer 1

1. Anchoring the plants firmly to substrate
2. Absorbing water and minerals
3. Producing hormone

Question 2

Types of Root Systems

Answer 2

1. Fibrous Root System
2. Tap Root System

Question 3

main root of a primary root system, growing vertically downward.

Answer 3

taproot

Question 4

increase the surface area of a plant’s root system and can be found in great abundance in several plant species

Answer 4

lateral roots

Question 5

cylindrical extensions of root epidermal cells that are important for acquisition of nutrients, microbe interactions, and plant anchorage

Answer 5

root hairs

Question 6

External Structure of Roots

Answer 6

• root hairs
• area of cell differentiation
• area of cell elongation
• area of cell division
• root cap

Question 7

Internal Structure of Roots

Answer 7

• root hair
• epidermis
• cortex
• stele

Question 8

central core of the stem and root of a vascular plant, consisting of the vascular tissue (xylem and phloem) and associated supporting tissue

Answer 8

stele

Question 9

outer layer of a stem or root in a vascular plant, lying below the epidermis but outside of the vascular bundles

Answer 9

cortex

Question 10

Primary meristems

Answer 10

1. Protoderm
2. Ground meristem
3. Procambium
4. Apical meristem

Question 11

Parts of stele

Answer 11

• endodermis
• pericycle
• phloem
• xylem

Question 12

thin layer of tightly packed cells that act as an impermeable barrier or water repellant layer (the Casparian strip) through which water can move only one way, toward the center of the root system

Answer 12

endodermis

Question 13

important tissue in roots, as this is the site where branch or secondary roots arise

Answer 13

pericycle

Question 14

the continuous arrangement of protoplasts of a plant, which are interconnected by plasmodesmata.

Answer 14

Symplast

Question 15

consists of non protoplasmic parts such as cell wall and intracellular space.

Answer 15

Apoplast

Question 16

between protophloem and metaphloem

Answer 16

tangential

Question 17

between companion cells and procambium cells

Answer 17

periclinal

Question 18

different arrangements of the number of protoxylem groups in roots in cross-sectional view

Answer 18

1. Diarch
2. Triarch
3. Tetrarch
4. Polyarch

Question 19

having two xylem strands or groups

Answer 19

diarch

Question 20

having three xylem strands or groups

Answer 20

triarch

Question 21

having four xylem strands or groups

Answer 21

tetrarch

Question 22

having many protoxylem groups

Answer 22

polyarch

Question 23

Features of Protoxylem and Metaxylem:
Time of formation

Answer 23

Protoxylem
- first formed xylem

Metaxylem
- late formed xylem

Question 24

Features of Protoxylem and Metaxylem:
Life time

Answer 24

Protoxylem
- short period

Metaxylem
- long period

Question 25

Features of Protoxylem and Metaxylem: Fibers

Answer 25

Protoxylem - lack fibers Metaxylem - has fibers

Question 26

Features of Protoxylem and Metaxylem: Vessels

Answer 26

Protoxylem - narrow in diameter Metaxylem - broader vessels

Question 27

Key to label: Dermal

Answer 27

epidermis

Question 28

Key to label: Ground

Answer 28

- cortex - endodermis

Question 29

Key to label: Vascular

Answer 29

- vascular cylinder - pericycle - core of parenchyma cells (monocots) - xylem - phloem

Question 30

guides root growth and development by modulating cell division, cell expansion and stem cell differentiation

Answer 30

auxin maximum

Question 31

found on the roots of plants, primarily legumes, that form a symbiosis with nitrogen-fixing bacteria

Answer 31

Root nodules

Question 32

nitrogen-fixing soil bacteria

Answer 32

rhizobia

Question 33

detached living portion of a plant (such as a bud or shoot) joined to a stock in grafting

Answer 33

scion

Question 34

- increase the absorptive and transport capacities of the root system - roots do not arise on pre-existing roots and are not radicles

Answer 34

adventitious roots

Question 35

- lubricates passage of the root through the soil - causes soil to release its nutrient ions and permits the ions to diffuse more rapidly toward the root

Answer 35

mucigel

Question 36

- thick layer of cells at forefront of growing tip - Cells secrete mucigel to help them glide through the soil but the soil is just plain scratchy and these cells are constantly being destroyed.

Answer 36

Root cap

Question 37

- Includes the apical meristem, which is a group of cells specialized for the production of new cells - located at the farthest point of the tissue or the organ produced (found in both shoots and roots) - just behind the root cap

Answer 37

Zone of Cell Division

Question 38

- Just behind the root apical meristem - region where cells expand greatly - some meristematic activity continues, but mostly cells are enlarging - Cells begin to differentiate into a visible pattern, although none of the cells is mature

Answer 38

Zone of Cell Elongation

Question 39

- The vascular tissues of the root become differentiated - Instead of forming bundles containing xylem and phloem, as in leaves and young shoots, the xylem forms a solid mass in the center, surrounded by strands of phloem

Answer 39

Zone of Maturation/ Zone of Cell Differentiation

Question 40

- taproot develops from the primary root (radicle) - there is one single large root with smaller branch roots

Answer 40

Taproot system

Question 41

- fibrous roots come out directly from the hypocotyl or may branch off from the primary root - the primary root degenerates so that there are many smaller roots of the same diameter and size

Answer 41

Fibrous root system

Question 42

Modifications in Roots

Answer 42

For 1. food storage 2. mechanical support 3. vital functions 4. other functions

Question 43

For storage of food

Answer 43

1. fusiform roots 2. napiform 3. conical 4. tuberous 5. fasciculated 6. nodulose 7. moniliform 8. annulated

Question 44

- spindle-shaped taproots - swollen in the middle and tapering on both ends

Answer 44

fusiform roots

Question 45

- spherical-shaped taproots - much swollen at the top and abruptly tapers towards the lower end

Answer 45

napiform roots

Question 46

- cone-shaped taproots - broad at the top and gradually tapers towards the lower end

Answer 46

conical roots

Question 47

- irregularly swollen taproots - does not form a definite shape

Answer 47

tuberous roots

Question 48

in adventitious roots, cluster of rootlets swollen at the base

Answer 48

fasciculated roots

Question 49

in adventitious roots, the slender root becomes swollen at the apex

Answer 49

nodulose roots

Question 50

in adventitious roots, the rootlets are repeatedly swollen giving a beaded appearance

Answer 50

moniliform roots

Question 51

in adventitious roots, the root has ring-like swellings

Answer 51

annulated roots

Question 52

For mechanical support

Answer 52

1. prop roots 2. stilt or brace roots 3. climbing roots 4. root buttress

Question 53

arise from stem branches and grow vertically downwards to the ground

Answer 53

prop roots

Question 54

arise from the nodes of the main stem

Answer 54

stilt or brace roots

Question 55

arise from the nodes and clasp a support like fence, stake or another plant

Answer 55

climbing roots

Question 56

in tall trees, the normal spreading taproots show ridge or plank like growth

Answer 56

root buttress

Question 57

For vital functions

Answer 57

1. assimilatory roots 2. respiratory roots or pneumatophores 3. floating roots

Question 58

other term for respiratory roots

Answer 58

pneumatophores

Question 59

roots become green and perform photosynthesis

Answer 59

assimilatory roots

Question 60

roots become aerotropic and come out of the soil to facilitate oxygen supply to the roots beneath

Answer 60

respiratory roots or pneumatophores

Question 61

- sponge roots with large aerenchyma providing buoyancy to the plant - also respiratory in function

Answer 61

floating roots

Question 62

For other functions

Answer 62

1. clinging roots 2. epiphytic roots 3. parasitic or haustorial or sucking roots 4. contractile or pull roots 5. epiphyllous roots

Question 63

in epiphytes, roots which arise to fix the plant to the substratum

Answer 63

clinging roots

Question 64

aerial roots covered by a hygroscopic velamen tissue which absorbs water from the air

Answer 64

epiphytic roots

Question 65

roots that penetrate the host plant and absorb nutrient from it

Answer 65

parasitic or haustorial or sucking roots

Question 66

roots that undergo contraction at the uppermost part due to the changes in the shape of the cortical cells

Answer 66

contractile or pull roots

Question 67

- roots arising from epiphyllous buds in some plant - become functional when the buds detach from the plant

Answer 67

epiphyllous roots