External and Internal Structure of Roots

Question 1

key adaptation for plants on land to allow access
nutrients and water stored in soil

Answer 1

plant roots

Question 2

FUNCTIONS OF ROOTS

Answer 2

§ Anchorage of the plant body in the soil
§ Absorption of water and minerals from the soil
§ Storage of foods
§ Conduction of food and water from the soil and from storage reserves
into the shoot

Question 3

TYPES OF ROOT SYSTEM

Answer 3

FIBROUS ROOT & TAPROOT

Question 4

§ Consist of a dense mass of slender, adventitious
roots that arise from the stem
§ The roots grow downward and outward from the
stem, branching repeatedly to form a mass of
fine roots.
Ex: grass and other monocots including lilies and
palm plants

Answer 4

FIBROUS ROOTS

Question 5

§ Features a single, dominant primary root
which grows straight down into the soil; much
smaller, fibrous secondary roots run outward
§ The large primary root can reach deep into the
soil for water and store food, adaptations
which help them to survive drought and
seasonal variations in temperature and
sunlight.
Ex: carrots, radish

Answer 5

TAPROOT

Question 6

after a bean germinated, what emerges from it that looks like a hook?

Answer 6

radicle

Question 7

It becomes the primary root (usually the most important root in
some plants)

Answer 7

radicle

Question 8

Other roots branch out from the primary root; called _________ ____

Answer 8

secondary roots

Question 9

found at the root tip, where new cells develop, covered by root cap

Answer 9

apical meristem

Question 10

protects the apical meristem from damage as it passes through coarse soil particles

Answer 10

root cap

Question 11

• An ideal system to study plant tissue formation
• Directing root growth in soil environment
• Adjusting soil environment by secretion and cell dispersal

Answer 11

root cap

Question 12

The surface of the root is protected by skin cells called the?
hint: Where water and minerals enter the root by osmosis and diffusion
Can grow long, hair like projections called root hairs (they greatly
increase the surface area of the root to allow more water intake)

Answer 12

epidermis

Question 13

root cap is composed of a _____________________________ covering the tip of each root

Answer 13

thimble-shaped mass of parenchyma cells

Question 14

function of root cap

Answer 14

Function: protects the root apical meristem
(RAM); protects the root from mechanical injury

Question 15

ROOT CAP

Dictyosomes or Golgi bodies release a
_________________________ lasts less
than a week, then these die

Answer 15

mucilaginous lubricant (mucigel) cells

Question 16

Possibly important in perception of gravity (i.e
geotropism or gravitropism)

Answer 16

ROOT CAP

Question 17

ROOT CAP

also called statoliths – dense
containing starch plastids, appear to accumulate at
the bottom of cells

Answer 17

Amyloplasts

Question 18

REGION OF CELL
DIVISION

Answer 18

Composed of apical meristem (cells divide
once or twice per day)

Question 19

REGION OF CELL DIVISION

The transitional meristems arise from the
tips of roots and shoots. These include:

Answer 19

§ Protoderm: forms the epidermis
§ Ground meristem: forms the ground
tissue
§ Pro cambium: forms the primary
phloem and xylem

Question 20

Cells become several times their original
length and also somewhat wider; the tiny
vacuoles merge and grow until one or two
large vacuoles, occupying up to 90% or
more of the volume of each cell have been
formed

Answer 20

REGION OF ELONGATION

Question 21

§ Root hairs develop as protuberances from
epidermal cells
§ Increase the surface area for the
absorption of water
§ Cuticle exists on root but not on root hairs

Answer 21

REGION OF MATURATION

Question 22

REGION OF MATURATION

this is where the root stores the
food produced by the leaves; it is made
out of parenchyma tissue

Answer 22

CORTEX

Question 23

REGION OF MATURATION

the inner boundary of the
cortex; one cell layer thick; controls the
movement of water and minerals into
the xylem and phloem

Answer 23

ENDODERMIS

Question 24

REGION OF MATURATION

a layer found inside the
endodermis which may produce lateral
roots; also produces vascular cambium
in dicots

Answer 24

PERICYCLE

Question 25

REGION OF MATURATION forms the central cylinder of the root; it is made out of two secondary transport tissues

Answer 25

Vascular cylinder/stele

Question 26

REGION OF MATURATION carries the water taken in by the root hairs and epidermis up the plant to the stems and leaves

Answer 26

Xylem

Question 27

REGION OF MATURATION carries the food produced by the leaves down to the roots to be stored in the cortex

Answer 27

Phloem

Question 28

SPECIALIZED ROOTS

Answer 28

§ FOOD STORAGE ROOTS § WATER STORAGE ROOTS § PROPAGATIVE ROOTS § PNEUMATOPHORES § AERIAL ROOTS § BUTRESS ROOTS § CONTRACTILE ROOTS § PARASITIC ROOTS

Question 29

In certain plants, the roots or part of the root system is enlarged in order to store large quantities of starch and other carbohydrates. carrots, beets and turnips have storage organs that are actually a combination of root and stem.

Answer 29

FOOD STORAGE ROOTS

Question 30

Plants that grow in particularly arid regions are known for growing structures used to retain water. Some plants in pumpkin family produce huge water storing roots. The plant will then use the stored water in times or seasons of low precipitation. Some cultures will harvest the water storing root and use them drinking water.

Answer 30

WATER STORAGE ROOTS

Question 31

§ The root word of this one means to produce more of oneself. Its structures are a way for a plant to produce more of itself. § Adventitious buds are buds that appear in unusual places. Many plants will produce these buds along the roots that grow near the surface of the ground. suckers, or aerial stems with rootlets, will develop from these adventitious buds. The new plant can be separated from the original plant and can grow independently.

Answer 31

PROPAGATIVE ROOTS

Question 32

§ Breathing roots to help plants that grow in very wet areas like swamps get enough oxygen. These roots basically act like snorkel tubes for plants, rising up above the surface of the water so that the plant can get oxygen. § Ex. mangrove trees

Answer 32

PNEUMATOPHORES

Question 33

§ There are many different kinds of these roots produced by a wide variety of plants. § Orchids produce vela men roots, corn plants have prop roots, ivies have adventitious roots and vanilla orchids even have photosynthetic roots that can manufacture food. § Banyan trees have aerial roots that grow down from the tree branches until they touch the soil. § These are roots that are not covered by soil hence out in the air. § They can facilitate climbing and various types of support.

Answer 33

AERIAL ROOTS

Question 34

§ These are large roots on all sides of a shallowy rooted tree. § Typically, they are found in nutrient-poor rainforest soils and do not penetrate to deeper layers. § Almost all types of mangroves have these types of roots. § They prevent the tree from falling over while also gathering more nutrients.

Answer 34

BUTRESS ROOTS

Question 35

§ These roots continually pull the plants deeper into the ground as the stem elongates so that it remain subterranean or at an appropriate level in the ground. § These are usually broad, fleshy, vertical, tapering, wrinkled looking and very distinct of the after cylindrical fine absorbent roots and are capable of incredible effort

Answer 35

CONTRACTILE ROOTS

Question 36

§ These roots are found in non-green parasitic plants. § These plants cannot make their own food and obtain food from the host. § These plants have no chlorophyll necessary for photosynthesis. § Dependent on chlorophyll-bearing plants for their required food materials, adventitious roots from the nodes of these plants penetrate into the host tissue (via peg like projections called haustoria) and enter into its conducting tissue (water-conducting and food-conducting) to acquire their nutrition.

Answer 36

PARASITIC ROOTS

Question 37

§ Forms a mutualistic association with plant roots § Fungus can absorb and concentrate phosphorous much better than it can be absorbed by the root hairs § Particularly susceptible to acid rain

Answer 37

MYCORRHIZAE

Question 38

- A swelling on the root of a leguminous plant, such as pea or clover, that contains bacteria of the genus Rhizobium, capable of nitrogen fixation § Root knots § swellings that may be seen in the roots of tomatoes and many other plants that develop in response to the invasion of tissue by small, parasitic roundworms (nematodes).

Answer 38

ROOT NODULES