Chapter 5 - Roots And Soils

Question 1

Region of cell division

Answer 1

*Apical meristem. Primary growth in length.

Question 2

Protoderm

Answer 2

A

Question 3

Ground meristem

Answer 3

A

Question 4

Region of elongation

Answer 4

• “Kid” stage (growing bigger, but don’t know what they’re going to do in life yet)

Question 5

Region of maturation/differentiation

Answer 5

• Cells develop in specialization

Question 6

Peocambium

Answer 6

A

Question 7

Root cap

Answer 7

• “Helmet” for the root.
• Function: protection to the root while it grows and pushes through abrasive soil. Produces a mucus for lubrication. Controls direction of growth (sensitive to gravity).

Question 8

Root-hair zone

Answer 8

• Another name for the region of maturation, where root hairs develop.

Question 9

Root hairs

Answer 9

Extended growth of epidermal cells (trichomes) to increase root surface area and increase soil contact for absorption of water and nutrients

Question 10

Cortex

Answer 10

• Largest region of the root, composed of parenchyma

* Function: storage, some support, transport (movement can go around or through the cells)

Question 11

Endodermis

Answer 11

• Function: acts as a filter for incoming materials

* Contains the Casparian strip; is a tube all the way down the root

Question 12

Casparian strip

Answer 12

• Like the “caulk” of the endodermis, between the cells to force materials to either enter the vascular tissue through the cells, or be blocked from entrance
• Function: seals the endodermal layer, filters materials

Question 13

Passage cells

Answer 13

• At the ends of “arms” of xylem. Small, thin-walled gaps in the endodermis.
• Function: to help channel water directly to the xylem and help prevent it entering the phloem.

Question 14

Vascular cylinder

Answer 14

• The core of tissues inside the endodermis.

Question 15

Pericycle

Answer 15

• Thin layer of meristematic cells inside the endodermis, usually one cell wide.
• Function: makes new cells, can result in side (lateral) roots, and parts of the vascular cambium in dicots come from the pericycle.

Question 16

Food-storage roots

Answer 16

Roots are enlarged to store large quantities of starch and other carbohydrates. Ex: sweet potatoes and yams, and dandelions.

Question 17

Water-storage roots

Answer 17

Store water, in arid areas

Question 18

Propagative roots

Answer 18

Ex: make stem cells turn into root cells in cuttings. Some plants produce them naturally, when send out suckers via the roots. They begin a new plant.

Question 19

Pneumatophores

Answer 19

• Root extensions above the soil surface. Found usually in tropical/swamp species where the soil can be saturated.
• Function: Aid in oxygen and other gas exchange.

Question 20

Aerial (“prop”) roots

Answer 20

• Roots originating above the surface of the soil. Vines produce these, that climb houses and trees. Corn grows prop roots to help stabilize the plant in wind.
• Function: support

Question 21

Contractile roots

Answer 21

Pull the plant deeper into the soil until stable soil temperature is found.

Question 22

Buttress roots

Answer 22

Tall, narrow “feet” that merge in appearance with the trunk. Gives great stability.

Question 23

Parasitic roots/plants

Answer 23

Feed off something else due to an inability to produce what it needs for itself. Example: dodder, a yellow plant lacking in chlorophyll, so takes nutrients from other plants

Question 24

Adventitious Roots

Answer 24

Roots that arise/grow from an unexpected location, such as propagation roots and aerial roots

Question 25

Mycorrhizae

Answer 25

A symbiotic relationship between specific fungus and plant roots where the mycelium join the root system. Fungus gives plant nutrients it can’t absorb as well by itself; plant gives fungus sugars it can’t synthesize.

Question 26

Root nodules

Answer 26

Joining of bacteria to roots; fixes nitrogen (legumes).

Question 27

Roots

Answer 27

• 2 forms: tap root, fibrous root system
• Functions: anchor the plant, absorb water and nutrients, transport materials (water, nutrients, sugar and starches), storage (but not annuals), growth
• Majority are in top 18” of soil; do extend beyond the drip line.
• New roots at ends do most of the absorbing; older roots are for storage and support.

Question 28

Tap root

Answer 28

Better for stability; reaches further down into the ground for minerals and water

Question 29

Fibrous root system

Answer 29

Better for erosion control. Redwoods have this, but intertwine with other trees’ roots to form a stable mat.

Question 30

Layers of the root

Answer 30

1) Epidermis
2) Cortex
3) Endodermis
4) Pericycle
5) Vascular tissue/cylinder

Question 31

Epidermis

Answer 31

Protection against organisms in the soil, temperature, absorption of water and nutrients, produce root hairs (trichomes)

Question 32

2 plant types

Answer 32

1) Monocotyledons (monocots)

2) Dicotyledons (dicots)

Question 33

Monocotyledons/monocots

Answer 33

• In grass family (grains, corn, etc.).
• Has one cotyledon (storage part of the seed)
• Vessel cell (xylem) arrangement in vascular cylinder is circular.

Question 34

Dicotyledons/dicots

Answer 34

• Has 2 cotyledons in storage part of the seed.
• Think: peanuts with 2 halves, beans, walnuts.
• Vessel cell (xylem) arrangement in vascular cylinder has “arms”; many form an “X” with xylem

Question 35

Fungus

Answer 35

2 main parts:

1) Mushroom - reproductive structure to produce spores
2) Hyphae (singular)/Mycelium (plural) - thread-like structure that breaks down organic matter and absorbs nutrients vie enzymes; usually living in the soil