Ch 7

Question 1

Radicle

Answer 1

the main root of a seed; it is the direct continuation of the embryonic stem

Question 2

Taproot system with lateral roots

Answer 2

fleshy roots that are the plants main site of carbohydrate storage during the winter; fine lateral roots growing but removed before they are sold; carrots, beets, turnips

Question 3

Fibrous root system

Answer 3

many similarly sized roots in most monocots and some eudicots

Question 4

Adventitious roots

Answer 4

roots that form on leaves, nodes or cuttings rather than on another root; an organ that forms in an unusual place; increase the absorptive and transport capacity of the root system

Question 5

Root cap

Answer 5

a thick layer of cells that protects the root apical meristem

Question 6

Mucigel

Answer 6

a complex polysaccharide which lubricates passage of the root through the soil secreted by the dictyosomes of root cap cells

Question 7

Apical meristem

Answer 7

regular files of cells that originate in the meristem and extend into regions of mature root tissues

Question 8

Quiescent center

Answer 8

mitotically inactive central region

Question 9

Zone of elongation

Answer 9

just behind the root cap and root apical meristem only a few mm long within which the cells undergo division and expansion

Question 10

Protoderm

Answer 10

any immature epidermal cell

Question 11

Protoxylem

Answer 11

the part of the primary xylem that differentiates early, while adjacent cells are still elongating

Question 12

Protophloem

Answer 12

the part of the primary phloem that differentiates early, while adjacent cells are still elongating

Question 13

Ground tissue

Answer 13

The tissue of a plant other than the epidermis, periderm, and vascular tissues, consisting primarily of collenchyma, parenchyma, and sclerenchyma. Cortex and pith are types of ground tissue

Question 14

Zone of Maturation/ root hair

Answer 14

root hairs grow outward, which increases the absorption of water and minerals

Question 15

Epidermis with root hairs

Answer 15

epidermal cells extend out as narrow trichomes; root hairs form only part of the root that is not elongating, otherwise they would be shorn off

Question 16

Epidermis with Casparian strips

Answer 16

layer of impermeable lignin and suberin in the walls of endodermal cells, preventing diffusion of material through that portion of the wall

Question 17

Cortex

Answer 17

primary tissue located between the epidermis and the phloem

Question 18

Metaxylem

Answer 18

the part of the primary xylem that differentiates late, after adjacent cells have completed their elongation

Question 19

Metaphloem

Answer 19

the part of the primary phloem that differentiates late, after adjacent cells have completed their elongation

Question 20

Pericycle

Answer 20

an irregular band of cells in the root, located between the endodermis and the vascular tissue

Question 21

Mature root

Answer 21

continued maturation of the endodermis is the formation of a watertight sheath around vascular tissues to keep water in; underlying cortex and epidermis often die and are shed from the root

Question 22

Xylem

Answer 22

the water and mineral conducting portion of vascular tissues. containing either tracheids or vessel elements or both

Question 23

Phloem

Answer 23

involved in conducting sugars and other organic compounds along with some water and minerals

Question 24

Lateral roots

Answer 24

initiated by cell divisions in the pericycle

Question 25

Storage roots

Answer 25

store carbohydrates; in biennial species and many perenials roots are the only organ

Question 26

Prop roots

Answer 26

transport additional water and minerals to the stem after they come in contact with the soil; they place some tension on the stem and act as stabilizers; strong supports; adventitious roots that extend to the soil

Question 27

Buttress roots

Answer 27

upper side grows more rapidly than the underside of the root; brace the trunk from being blown over by wind

Question 28

Aerial roots

Answer 28

orchids; roots dangle freely because the orchid lives attached to branches of trees; roots have a waterproof barrier

Question 29

Contractile roots

Answer 29

after roots extend through the soil and firmly attach the uppermost portions begin to contract; stem is pulled downward; contraction caused by changes in the shape of cortex cells

Question 30

Mycorrhizae

Answer 30

fungi that forms a symbiotic relationship with roots, usually of benefit to plants because they provide phosphorus

Question 31

Ectomycorrhizae

Answer 31

a type in which the fungi invade only the outermost cells of the root

Question 32

Endomycorrihizae

Answer 32

a type in which the fungi invade all cells of the root cortex

Question 33

Root Nodules

Answer 33

in the root’s inner cortex where adjacent cortical cells undergo mitosis and form root nodules

Question 34

N-fixation

Answer 34

chemical conversion of atmospheric nitrogen into usable compounds; nitrogen scarcity is one of the main growth-limiting factors for plants

Question 35

Parasitic haustoria

Answer 35

the structure by which a parasite enters and draws nutrients from a plant; in fungi it is hypha; in mistletoes and similar parasites it is a modified root

Question 36

Strangler figs

Answer 36

roots of strangler figs cling to bark of host tree branch and grow downward; they absorb nutrients from rainwater that runs down the host tree; when the roots finally hit the soil the roots branch and encircle host tree until it does or rots