Ch. 5 Roots

Question 1

Describe Roots

Answer 1

o Anchor trees firmly in soil
o Branching networks on average 10-16 ft, but can vary highly
o Anchor plants
o Absorb water and minerals in solution through feeder roots
o Other specialized functions

Question 2

Root hairs

Answer 2

tubular extension of living epidermal cells in the root
 Enhances absorptive capacity when large surface area
 Cuticle of root hairs thin enough to allow water to pass through, but is thick enough to protect root hairs from bacteria and fungal infections

Question 3

Embryo

Answer 3

immature plant with germinating seed

Question 4

Radicle

Answer 4

the part of the embryo in a seed that develops into a root

Question 5

Describe development of dicot root systems

Answer 5

 Two seed leaves
 Taproot systems with one or occasionally more primary roots from which secondary roots develop (Characterized by single large root with smaller branch roots)

Question 6

Describe development of monocot root systems

Answer 6

o Monocots: fibrous root systems
 Characterized by smaller roots of similar diameter

Question 7

Adventitious roots

Answer 7

develop from stem or leaf, NOT from another root

Question 8

Name the 4 zones of young roots

Answer 8

root cap, region of cell division, region of elongation, region of maturation

Question 9

Describe young root root cap

Answer 9

• Distinct structure
• Thimble-shaped mass of cells at the tip of a growing root
• Functions primarily in protection
• Parenchyma cells
• Covers tip of root
• Formation of root behind it pushes it into the soil

secretes mucilage as lubricant

Question 10

Describe the life span of a root cap

Answer 10

• 1 week
  o While new one forms, amyloplasts collect on the bottom of the root-cap cells; this helps prevent uneven growth

Question 11

amyloplasts

Answer 11

colorless, starch-forming plastic found in roots and involved in gravity perception

Question 12

Describe young root region of cell division

Answer 12

• Apical meristem
• Most cell divisions take place next to root cap at the edges of iverted cup-shape zone, behind meristem base
• Rhythmic division
• Cubical shape
• Large nuclei
• Very few small vacuoles
• Apical meristem divides into three meristematic areas

Question 13

Three meristematic areas of apical meristem

Answer 13

protoderm, ground meristem, and procambium

Question 14

protoderm

Answer 14

produces epidermis

Question 15

ground meristem

Answer 15

produces parenchyma cells of the cortex, cortex and pith development

Question 16

procambium

Answer 16

solid cylinder shape, produce primary xylem and primary phloem

Question 17

Describe young root region of elongation

Answer 17

• Area near an apical meristem in which cells grow in length and width; Cells in region of elongation become several times longer than wide (rare exceptions exist)
• Right before tip of root
• Larger and wider cells
• Small vacuoles combine to form large vacuole
• Root growth, but no girth unless cambium present

Question 18

Region of maturation

Answer 18

• Area of maturing cells near an apical meristem
• Forming into distinct cell types in root-hair zone

Question 19

root-hair zone

Answer 19

area of cells in a root which protuberances of epidermal cell can be found

Question 20

root hairs

Answer 20

absorb water and minerals, adhere tightly to soil
 Tubular extensions of specialized epidermal cells