2 ... 13 - Roots

Question 1

Major root functions?

Answer 1

anchorage
absorption
conduction
storage

Question 2

Main forms of root structures?

Answer 2

fibrous system

tap root system

Question 3

Describe tap root system

Answer 3

one prominent main root with small, lateral roots branching from it

Question 4

Describe fibrous root system

Answer 4

many adventitious roots of ~equal size, arising from stem base

Question 5

Monocots typically have ___ root systems.

Answer 5

fibrous

Question 6

Eudicots typically have ___ root systems.

Answer 6

tap

Question 7

RAM…

Answer 7

root apical meristem

Question 8

Three zones of growth in root?

Answer 8

1. zone of cell division (includes meristem… ‘bottom’)
2. zone of elongation (cell expansion… middle)
3. zone of maturation (cell differentiation… top)

Question 9

Describe root cap

Answer 9

covering of cells over root tip that protects delicate meristematic tissue directly behind it

Question 10

Define root hair

Answer 10

extension of epidermal cell of root that greatly increasing absorptive capacity of root (maturation zone)

Question 11

Basic root structure, inside out?

Answer 11

Vascular tissue
Endodermis
cortex
root cap/epidermis

Question 12

Describe eudicot roots

Answer 12

xylem and phloem form solid mass in center known as vascular center (surrounded by pericycle and endodermis)

Question 13

Describe monocot roots

Answer 13

pith in center, surrounded by ring of vascular tissue

Question 14

Function of epidermis?

Answer 14

protects root, … hairs help absorb water and dissolved minerals

Question 15

Function of cortex?

Answer 15

stores starch, consists of parenchyma cells

Question 16

Describe endodermis

Answer 16

innermost layer of root cortex, prevents water and dissolved minerals from simply entering xylem… forces everything to enter by passing between cells

Question 17

Two ways of moving water in root cortex?

Answer 17

1. symplasticly

2. apoplasticly

Question 18

Symplastic water movement

Answer 18

intracellular, through cells (cytoplasm) … casparian strips

Question 19

Apoplastic water movement

Answer 19

interconnected cell-wall spaces

Question 20

Describe casparian strips

Answer 20

band of waterproof material around cell walls of endodermis… ensures water and minerals enter xylem ONLY by passing THROUGH endodermal cell interior

Question 21

Describe pericycle

Answer 21

layer of cells just inside endodermis of root (outermost layer of vascular tissue)… where lateral roots emerge

Question 22

Describe adventitious roots

Answer 22

roots that develop from stem… thicker, provide extra support. aka prop roots

Question 23

other ways roots can absorb water and nutrients from soil?

Answer 23

1. mycorrhizae

2. nodules

Question 24

Describe mycorrhizae.

Answer 24

mutualistic fungi/root relationship. helps absorb minerals from soil… increases surface area

Question 25

Describe nodules.

Answer 25

small swelling on root in leguminous plant… N-fixing bacteria live here