Roots

Question 1

What do roots prevent?

Answer 1

Erosion

Question 2

The radicle

Answer 2

First root of the plant, develops at seed germination, first to emerge from a seed

Question 3

Adventitious roots

Answer 3

Emerge after the germination period, from stems and leaves

Question 4

Taproot roots

Answer 4

Unbranched, straight, gradually tapering

Question 5

Fibrous roots

Answer 5

Very branched, many lateral roots, thin

Question 6

Purpose of the root cap

• Secretes?
• Gravity?

Answer 6

• Protects apical meristem
• Secretes a substance that facilitates root penetration in the soil and acts as a growth medium for beneficial organisms
• Gravity sensor that allows the root to go to the center of the earth

Question 7

Region of cell division

• Protoderm?
• Ground meristem?
• Procambium?

Answer 7

• Produces the epidermis
• Parenchyma in cortex
• Vascular elements - x&p

Question 8

Cortex

Answer 8

Exo/Endodermis and storage parenchyma

Question 9

Region of Maturation

• Purpose
• Parts

Answer 9

• Cells begin to differentiate
  1. Epidermis
  2. Cortex
  3. Vascular cylinder

Question 10

Vascular cylinder (2)

Answer 10

• Pericycle (thin layer of cells b/w endodermis and the phloem)
• Primary xylem and phloem

Question 11

In the roots, xylem is

Answer 11

Exarch (protoxylem on the outside and metaxylem in the inside)

Question 12

Casparian strips

Answer 12

Interal and lateral cells walls thickened with bands of lignin

Question 13

Primary origin of xylem and phloem

Answer 13

From the procambium, primary meristem

Question 14

What proto develops first?

Answer 14

Xylem

Question 15

Order of xylem development

Answer 15

Procambium meristem -> proto -> meta -> primary -> secondary

Question 16

Monocots dont form

Answer 16

vascular cambium and cork cambium

Question 17

Secondary structure develops from …

Answer 17

• secondary meristems which develop within the primary structure
• SM, VC, CC will produce secondary tissue that will either mix with or replace the primary tissue

Question 18

Exterior of the primary xylem strands forms

Answer 18

the pericycle

Question 19

Why does the VC go from star to circle

Answer 19

• because it divides more intensely at the interior of the phloem and acquires a circular shape

Question 20

How is the primary phloem crushed

Answer 20

• V.C. produces toward the interior of the root 2nd xylem, pushes 1st xylem towards the center
• At the same time it produces towards the exterior secondary phloem which crushes it

Question 21

Lateral roots develop from

Answer 21

Pericycle

Question 22

Mutualistic relationship between:

• Roots (provides)
• Rhizobia (provides)

Answer 22

• Carbon & source of energy for growth

- Fix atmospheric nitrogen and provides the plant with a source of reduced nitrogen

Question 23

Order of nitrogen fixation

Answer 23

1. Roots produce flavo/isonoids when they need n2
2. Rhizobia produce Nod Factors and respond
3. Infection threads form by the root hairs
4. Plant produces nodulin to host the rhizobia

Question 24

Mycorrhiza?

• Plant provides?
• Fungus?

Answer 24

Mutalisitic relationship between a plant and a fungus

• Carbon
• Increases the absorption capacity of the roots, stimulates plant resistance to different diseases

Question 25

Ectomycorrhizas - Mantle? - Hartig net? - Penetrates?

Answer 25

- Dense network of hypae that cover the root - Surround plant cells w/i the root cortex - Root cortex cells

Question 26

Mycoheterotropic plants

Answer 26

- Depend on parasitic relationship | - Parasitize the mycorrhizal relationship of other plants and takes nutrients from both

Question 27

Storage roots

Answer 27

Specially modified to store starch and water

Question 28

Propagative roots from adventitious buds

Answer 28

If they break, fragments with buds can regenerate new plant

Question 29

Propogative roots - Parent tree and new root suckers

Answer 29

New root suckers suck resources from parent trees until they're seperated

Question 30

Pneumatophors

Answer 30

Aerial roots that evolved in certain plants growing in swamps and marshes for gas exchange

Question 31

- Prop roots | - Buttress roots

Answer 31

- Aerial roots - adventitious orgin on the stem, grow down and root in soil, anchor the plant (e.x. corn) - Support role, tropical tree species

Question 32

Epiphytic plants - root type? | - Specialized epidermis?

Answer 32

- Photosythetic (e.g. orchids) | - Absorbs water from the air using a specialized epidermis called velamen

Question 33

Climbing roots

Answer 33

Attach themselves to other trees (e.g. poison ivy) - Lianas

Question 34

Contractile roots

Answer 34

Stems such as bulbs, corms and rhizomes - wrinkled transversally - Contract longitudinally - can pull deeper

Question 35

``` Parasitic plants (noxious weed) specialized organ - How? ```

Answer 35

Haustorium: Take water and nutrients from host | - Attaches to and penetrates into the host stem and connects to its vasculature