Roots & Structure

Question 1

Root Functions

Answer 1

Support (anchoring)
Absorb water and minerals
Conduct water and minerals to and fro the shoots
Store water or food

Question 2

How do roots develop?

Answer 2

The embryo contains a radicle that is the embryonic root of the plant.

The radicle develop into a long taproot or many adventitious roots

Question 3

Adventitious roots develop

Answer 3

develop from a stem or leaf, not another root

Question 4

Fibrous root system development

Answer 4

A system that may have large numbers of fine roots of similar diameter, then develops from the adventitious roots

Question 5

4 Regions of Young Root Structures

Answer 5

1, The root cap
2. The region of cell division
3. The region of elgonation
4. The region of maturation

Question 6

Root cap and functions

Answer 6

Composed of a thimble-shaped mass of parenchyma cells covering the tip of the root

It protects the delicate tissues behind it from damage as it pushes through soil particles.

It provides a perception of gravity.

Question 7

Root Cap Perception of gravity

Answer 7

Amyloplasts act as gravity sensors, collecting on the bottom of the root cap cells. They tumble or float down to the bottom of the cells in which they occur

Question 8

Three meristematic areas of the root

Answer 8

1. Protoderm
2. Ground meristem
3. Procambium

Question 9

Protoderm

Answer 9

Region of cell division in the root that gives rise to an outer layer of cells, the epidermis

Question 10

Ground Meristem

Answer 10

Produces parenchyma cells of the cortex in the root

Question 11

Procambium

Answer 11

Produces primary xylem and primary phloem

Question 12

Pith

Answer 12

Parenchyma tissue that originates from the ground meristem.

Generally present in stems, but absent in most dicot roots.

Present in grass roots of most monocots.

Question 13

Region of Elongation

Answer 13

merges with the apical meristem to lengthen the root by merging tiny vacuoles and grow until one or two large vacuoles have been formed.

Question 14

Root Cap Root Movement

Answer 14

Dictoyosomes in the root cal’s outer cells secretes a slimy substance that moves into the cell walls and eventually exit through shedding of the outer cells that form a slimy lubricant to move through the soil

Question 15

Region of Maturation

Answer 15

aka region of differentiation
aka root-hair zone

where most cells differentiate into various distinctive types of primary tissues in this regions

Question 16

Root hairs

Answer 16

tubular extensions of specialized epidermal cells that absorb water and minerals, adhere tightly to soil particles

Question 17

Cortex

Answer 17

tissue composed of parenchyma made of loosely packed cells that allow water and minerals to move through the cortex without entering the cells. It stores food

Question 18

Endodermis

Answer 18

consists of a single-layer cylinder of compactly arranged cells whose primary walls are impregnated with suberin bands called Casparian strips. The plasma membranes of the endodermal cells are fused to the Casparian strips

Question 19

Pericycle

Answer 19

a one cell wide parenchyma tissue lying directly against the inner boundary of the endodermis

Question 20

Two Paths of water and mineral movement

Answer 20

1. Apoplastic
2. Symplastic

Question 21

Apoplastic

Answer 21

movement of water and minerals through cell walls and intercellular spaces. Resistance to flow is about 50x less than resistance of symplastic movement

Question 22

Symplastic

Answer 22

movement of water and minerals through living cells with a greater resistance to water flow

Question 23

Adaptations of Food-Storage Roots

Answer 23

Enlarged and store large quantities of starch and other carbohydrates

In carrots, beets, turnips, and radishes, the food storage tissues are a combo of root and stem

Question 24

Adaptations of water-storage roots

Answer 24

characteristic of plants that grow in arid regions with low to no precipitation

Question 25

Propagative Roots

Answer 25

Roots with adventitious buds near the surface of the ground

Question 26

Adventitious Buds

Answer 26

Buds appearing in places other than stems, like on roots.

Question 27

Pneumatophores

Answer 27

Special spongy roots that extend above the water’s surface and enhance gas exchange in mangroves and other aquatic environments

Question 28

Examples of Aerial Roots

Answer 28

Velamen roots of orchids for moisture retention Prop roots of corn and banyan trees for support against wind Adventitious roots of ivies for climbing

Question 29

Contractile Roots and FUnction

Answer 29

Roots that pull the plant deeper into the soil (found in bulbous plants) Used to obtain natural resources, protect from herbivory, and protect from the environment.

Question 30

Buttress Roots

Answer 30

Huge angular roots that look like part of the trunk found on some tropical trees growing in shallow soil that promotes stability.

Question 31

Parasitic Roots

Answer 31

Roots of plants WITHOUT CHLOROPHYLL that use tiny peglike projections called haustoria to penetrate the outer tissues and establish connections with the xylem and phloem of another plant

Question 32

Haustoria

Answer 32

The peg-like projections of parasitic roots that penetrate the outer tissues of other plants to establish connections with its xylem and phloem

Question 33

Mycorrhizae

Answer 33

fungi with a mutualistic relationship with the roots of many plants

Question 34

Mycorrhizae Benefits to the Plant

Answer 34

Can absorb and concentrate P much better than root hairs. Facilitate absorption of water and nutrients through millions of threadlike strands

Question 35

Mycorrhizae Symbiosis benefits for the fungi

Answer 35

The plant provides sugars and amino acids that fungi cannot survive without

Question 36

Ectomycorrhizae

Answer 36

Mycorrhizae where the fungal hyphae penetrate the root cortex, BUT DON’T ENTER THE CELL common in pines and oaks

Question 37

Endomycorrhizae

Answer 37

Mycorrhizae where the hyphae that pentrates the root cells, but LACKS A MANTLE Found in most woody and herbaceous land plants