Roots Module 4

Question 1

What are the typical functions of roots?

Answer 1

anchorage, uptake of nutrients and water, storage (rhizomes), hormone production

Question 2

Specialized functions in roots? Examples too.

Answer 2

brace roots - corn, banyon
air roots - fig (pneumatophores)
photosynthetic roots for anchorage - orchid
parasitic roots - dodder

Question 3

Basic Structure of a root?

Answer 3

Root cap, Region of cell division, region of elongation, Region of maturation and differentiation.

Question 4

What does the root cap do?

Answer 4

Protection of the growing apex as it pushes through the soil and produces mucilage to aid in movement. Also the preception of gravity (geotropism)

Question 5

Region of cell division important

Answer 5

It’s where cell division takes place, located in the tip

Question 6

Region of cell elongation

Answer 6

cell expansion and increase in length

Question 7

Region of cell maturation and differentiation

Answer 7

where cells mature, increase in size, form root hairs and differentiate into different tissues

Question 8

What makes up the epidermal tissue system?

Answer 8

Epidermis and root hairs

Question 9

What does the epidermis do?

Answer 9

Offers protection, it has a waxy cuticle (prevent water loss), a pest barrier (fungi, nematodes)

Question 10

Root hairs

Answer 10

Uptake of water and nutrients, but they are short lived not more than 2 weeks.
root hairs can be destroyed by fertilizer burn, and pests reduce number of hair, and they are susceptible to transplant shock
One 4-mos rye plant can have 14 billion root hairs, an absorbing surface of 401 cubic meters

Question 11

What is the ground tissue system made up of?

Answer 11

Cortex and endodermis

Question 12

What is the cortex?

Answer 12

Storage; for the needs of molecules or waste
the cells are alive

Question 13

What is the endodermis?

Answer 13

inner boundary of the ground tissue system, they possess a special waxy substances in the cell wall (casparian strip)
forces nutrients and water to enter the cell through the plasmodesmata which are then filtered directly to the xylem.

Question 14

What are plasmodesmata?

Answer 14

They are channels from the cytoplasm of one cell to the next cell.

Question 15

What is the Vascular tissue system made up of?

Answer 15

The xylem, phloem, pericycle, and vascular cambium (only in dicots)

Question 16

What is the xylem?

Answer 16

The transport of water and nutrients over long distances, only moves upwards towards the stem.

Question 17

What is the phloem?

Answer 17

Transports the products of photosynthesis (sugars and starches) to all parts of the plant (can move up and down.
They possess many mitochondria for energy production and are a living tissue.

Question 18

What is the pericycle?

Answer 18

Storage and the site of formation for lateral branches

Question 19

Lateral branches in roots

Answer 19

They form from the pericycle
branches push their way through the side of the root
lateral branches have the same structure as primary roots
The vascular systems between primary and lateral roots are connected

Question 20

Tap Root Systems

Answer 20

One main root (radicle) with many lateral branches
found in DICOT
ex soybean, vegetable root crops, tree species, flowers

Question 21

Fibrous Root Systems

Answer 21

many form from close to the shoot (stem) with many lateral branches
found mainly in MONOCOTS
ex corn, pasture grasses, turf, rice, bamboo, banana, and palm

Question 22

Fibrous roots VS Taproots

Answer 22

Water requirements differ; taproots can penetrate hard soil, fibrous do better in less compacted soil.
taproots are better at taking up deep water, dicots are water loving
monocots grow in drier environments

Question 23

Root Associations

Answer 23

Rhizobium and Mycorrhizae

Question 24

What is Rhizobium?

Answer 24

Most common legume association with the bacteria
a symbiotic relationship; plant gives bacteria 40% of it’s energy, nodules form and produce a fixed nitrogen for the plant

Question 25

What is Mycorrhizae?

Answer 25

an association between plants and fungi, different plants to different fungi, not a clear symbiosis
Mycorrhizae are thread ;like structures that wrap around the roots and root hairs
The fungus breaks down complex molecules into simple molecules for the plant, like phosphorus, they also create more surface area for nutrient uptake.