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Plant Biology > Ch 7 > Flashcards

Flashcards in Ch 7 Deck (36):
1

Radicle

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

2

Taproot system with lateral roots

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

3

Fibrous root system

many similarly sized roots in most monocots and some eudicots

4

Adventitious roots

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

5

Root cap

a thick layer of cells that protects the root apical meristem

6

Mucigel

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

7

Apical meristem

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

8

Quiescent center

mitotically inactive central region

9

Zone of elongation

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

10

Protoderm

any immature epidermal cell

11

Protoxylem

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

12

Protophloem

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

13

Ground tissue

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

14

Zone of Maturation/ root hair

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

15

Epidermis with root hairs

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

16

Epidermis with Casparian strips

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

17

Cortex

primary tissue located between the epidermis and the phloem

18

Metaxylem

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

19

Metaphloem

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

20

Pericycle

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

21

Mature root

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

22

Xylem

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

23

Phloem

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

24

Lateral roots

initiated by cell divisions in the pericycle

25

Storage roots

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

26

Prop roots

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

27

Buttress roots

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

28

Aerial roots

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

29

Contractile roots

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

30

Mycorrhizae

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

31

Ectomycorrhizae

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

32

Endomycorrihizae

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

33

Root Nodules

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

34

N-fixation

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

35

Parasitic haustoria

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

36

Strangler figs

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