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Internal structure of monocot root - class-XI

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Monocotyledonous root differs from dicot root in which of the following internal features (a to d)?


a. Presence of parenchymatous pericycle
b. Absence of fewer xylem bundles
c. Presence of large and well-developed pith
d. Presence of parenchymatous cortex without intercellular spaces

Find out the correct option.

  1. a, c, & d

  2. b & d

  3. b & c

  4. a & d


Correct Option: A

Read the  following statements and choose the correct option. 
a) Pith is large and well developed in roots of monocot plants.
b) Bundle sheath is  presents in dicot stem.
c) Water containing cavities are present within vascular bundles of monocot stem.

  1. Only (b) is incorrect

  2. Only (a) is incorrect

  3. Only (a) and (b) are correct

  4. All (a), (b) and (c) are correct


Correct Option: A
Explanation:

 In dicot stem, bundle sheath is absent, while in monocot stem the bundle sheath is present as it surrounds the scattered vascular bundles. So the correct option is 'Only (b) is incorrect'.

A typical monocotyledonous root is characterized by 

  1. Usually more than six xylem bundles

  2. Large and well developed pith

  3. No secondary growth

  4. All of the above


Correct Option: D
Explanation:
A typical monocotyledonous root can be characterized by :-
1) The xylem shows a polyarch condition where it forms numerous groups or bundles (usually 12 to 21).
2) The cambium is absent in all the stages and there is no secondary thickening in such roots.
3) The pith is large and well developed.
So, the correct answer is 'All of the above'.

Bundle sheath cells are similar to mesophyll cells in 
a. Having grana.
b. Having large number of chloroplasts
c. Being involved in $CO _2$ fixation
d. Being impervious to gaseous exchange
e. Their primary $CO _2$ fixation product.

  1. Only c& e

  2. Only c

  3. Only a,b& e

  4. Only a & d


Correct Option: A

The character of monocot is

  1. Net-veined leaves

  2. Annual rings

  3. Seed with two masses of stored food

  4. Conducting strands scattered in ground tissue


Correct Option: D
Explanation:

Net-veined leaves, annual rings and seed with two masses of stored food are characteristic features of dicots. 

In a monocotyledenos, the vascular bundles are not arranged in a circle but are usually scattered throughout the ground tissue. There is no clearly defined pith as there is in many dicotyledonous species. The vascular bundles of monocotylenous plants do not contain a layer of meristematic tissue (cambium) as the dicots do. Thus, no new cells can be formed inside the vascular bundles of monocots and their vascular bundles are termed as closed, whereas those of dicot plants are open. 

In monocots, root cap is formed by

  1. Dermatogen

  2. Calyptrogen

  3. Wound cambium

  4. Vascular cambium


Correct Option: B
Explanation:

Dermatogen is the histogen or meristematic regions of root and stem which is produced by apical meristem and give rise to uniseriate epidermis by anticlinal divisions; option A is incorrect. Monocotyledons have one additional histogen along with dermatogens, periblem and plerome Calyptrogen being the fourth one that makes root cap. The vascular cambium, also called as wood cambium, has thin walled highly vacuolated cells of two types, the fusiform initials and the ray initials. The fusiform initials are the elongated cells that give rise to secondary xylem and secondary phloem. Ray initials are horizontally organized and produce vascular rays (medullary rays or ray parenchyma). 

Thus, the correct answer is option B.

Monocot root differs from dicot root in having

  1. Open vascular bundle

  2. Scattered vascular bundle

  3. Large pith

  4. No pit


Correct Option: C
Explanation:

Pith is the innermost region of the root representing the central axis. It is composed of few loosely arranged parenchyma cells. Large pith is present in monocot roots. In dicot roots, pith is absent. Open vascular bundles are present in dicots. Scattered vascular bundles are present in moncot stem. Radial vascular bundles are present in both monocot and dicot roots.

Thus, the correct answer is option C.

Polyarch and exarch vascular bundles are the characteristic of

  1. Dicot stem

  2. Dicot root

  3. Monocot stem

  4. Monocot root


Correct Option: D
Explanation:

Monocot root vascular bundles are radial in arrangement. There are eight bundles each of xylem and phloem. Hence, the condition is described as polyarch. Xylem is described as exarch in them. 

Monocot stem vascular bundles are conjoint, collateral and closed. Xylem is endarch in them. Presence of only two protoxylem and two metaxylem vessels in each bundle. 
Dicot root vascular bundles are described as radial and tetrarch. There are four bundles each of xylem and phloem occurring alternately. Xylem is described as exarch. 
Dicot stem vascular bundles are eight in number, arranged in form of a broken ring. The vascular bundles are conjoint, collateral and open. Xylem is on the inner surface and phloem on the outer surface. Xylem is described as endarch. Thus, option D is correct.

Which of the following is correct sequence of layers in typical monocot root from outside to inside?

  1. Pericycle, cortex, endodermis, epiblema

  2. Epiblema, endodermis, cortex, pericycle

  3. Epiblema, cortex, endodermis, pericycle

  4. Epiblema, pericycle, cortex, endodermis


Correct Option: C
Explanation:

The sequence of layers in typical monocot root from outer surface to inside is epiblema, cortex, endodermis, stele, pericycle, conjunctive tissue, pith and vascular bundles. Thus, option C is correct.

Passage cells are more distinct in endodermis of

  1. Dicot stem

  2. Monocot stem

  3. Dicot root

  4. Monocot root


Correct Option: D
Explanation:

Passage cells are endodermal cells of older monocot roots which have retained thin walls and Casparian strips rather than becoming suberized and waterproof like the other cells around them, to continue to allow some symplastic flow to the inside. Experimental evidence suggests that passage cells function to allow transfer of solutes such as calcium and magnesium into the stele, in order to eventually reach the transpiration system. For the most part, however, old roots seal themselves off at the endodermis, and only serve as a passageway for water and minerals taken up by younger roots "downstream". Passage cells are absent in dicot roots, monocot stem and dicot stem.

Therefore, the correct answer is option D.

Passage cells are found in

  1. Monocot root

  2. Monocot stem

  3. Aerial root

  4. Dicot stem


Correct Option: A
Explanation:

Passage cells are endodermal cells of older roots which have retained thin walls and Casparian strips rather than becoming suberized and waterproof like the other cells around them, to continue to allow some symplastic flow to the inside. Passage cells function to allow transfer of solutes, such as calcium and magnesium into the stele, in order to eventually reach the transpiration system. 

Exarch and polyarch xylem strands are found in

  1. Monocot stem

  2. Dicot stem

  3. Monocot root

  4. Dicot root


Correct Option: C
Explanation:

In monocot root vascular bundles are radial in arrangement. There are eight bundles each of xylem and phloem. Hence, the condition is described as polyarch. Xylem is described as exarch in monocot root.

Exodermis occurs in

  1. Monocot root

  2. Dicot root

  3. Leaf

  4. Stem


Correct Option: A
Explanation:

In mature monocot roots, after the loss of epidermis, the outer cells of general cortex are suberised become thick-walled layer called exodermis.

So, the correct option is ‘Monocot root’.

A common character of monocot and dicot roots is

  1. Exarch protoxylem

  2. Endarch xylem

  3. Number of xylem strands

  4. Occurrence of secondary growth


Correct Option: A
Explanation:

The anatomy of dicot root and monocot root more or less similar in majority of characters. They are epidermis, general cortex, endodermis, type of vascular bundles, nature of xylem.

The common characters appear between the anatomy of dicot root and monocot root are 
Presence of single-layered epidermis
Presence of parenchymatous general cortex
Presence of single-layered endodermis with Casparian bands.
Presence of radial vascular bundles
Presence of exarch xylem.
So, the correct option is 'Exarch protoxylem'.

Pick u the wrong differences between dicot and monocot root.

Character Dicot Root Monocot Root
(a) Activity of pericycle Lateral root production Secondary growth and cambium
(b) Vascular bundle Diarch to tetrarch Polyarch
(c) Cambium Lateral, developed Absent
(d) Pith Well developed Poorly developed
  1. b, d

  2. a, c

  3. a, d

  4. a, b


Correct Option: C
Explanation:

a) Wrong – because in dicot root pericycle is meant for production of lateral roots and cambium whereas in monocot root it is pericycle is meant for lateral production only.

b) True – In dicot root stele is diarch to tetrarch, whereas in monocot root, stele is polyarchy.

c) True – In dicot root, cambium is developed laterally, whereas in monocot root, cambium is absent.

d) False – because, in dicot root is pith is poorly developed, whereas in monocot root pith is well developed.

So, the correct option is ‘a,d’.

Which plant part possesses polyarch condition of vascular bundles with a well developed pith?
  1. Dicot root

  2. Monocot root

  3. Dicot stem

  4. Monocot stem


Correct Option: B
Explanation:

A monocot root possesses polyarch (more than 4) condition of vascular bundle, here the vascular bundles are radial, closed with exarch condition of the xylem, embedded in the ground tissue that has a well developed central region or the pith or medulla.

So, the correct answer is 'Monocot root'

Polyarch vascular bundles generally occur in
  1. Monocot stem

  2. Dicot stem

  3. Dicot root

  4. Monocot root


Correct Option: D
Explanation:

Polyarch vascular bundle (more than 4)  is observed in monocot root. The vascular bundle is radial and closed, with exarch condition of the xylem. 

So, the correct answer is 'Monocot root'

A typical monocotyledonous root is characterised by -

  1. Usually more than six xylem bundles

  2. Large and well developed pith

  3. No secondary growth

  4. All of these


Correct Option: D
Explanation:
A typical monocotyledonous root can be characterized by: -
1) The xylem shows a polyarch condition where it forms numerous groups or bundles (usually 12 to 21).
2) The cambium is absent in all the stages and there is no secondary thickening in such roots.
3) The pith is large and well developed.
So, the correct answer is 'All of the above'.

Read the following statements :
(i). In monocot root, a large number of vascular bundles are arranged in the form of a ______ around the central ____
(ii). Due to the presence of _
, the endodermal cells do not allow wall to wall movement of substances between cortex and pericycle, in a primary dicot root.
(iii). The epidermis of stem of sunflower bears several unbranched __
___ hair.
(iv). The central portion of a dicot stem is usually occupied by ______ comprising of thin-walled parenchymatous cells
Select the option that correctly fills the blanks in any two of them.

  1. (i) ring, pith; (ii) hypodermis

  2. (ii) Casparian strips; (iii) unicellular

  3. (i) ring, cortex; (iv) vascular bundles

  4. (iii) multicellular; (iv) pith


Correct Option: D
Well developed pith is found in
  1. Monocot root and monocot stem

  2. Monocot stem and dicot root

  3. Monocot root and dicot stem

  4. Dicot root and dicot stem


Correct Option: C
Explanation:

Well developed pith or parenchymatous central region is present in monocot root (maize) and dicot stem (Sunflower). Its a structure of loosely arrannged cells that embeds vascular tissue, it may store food.

So, the correct answer is 'Monocot root and dicot stem'

Polyarch condition is found in

  1. Monocot root

  2. Dicot root

  3. Monocot stem

  4. Dicot stem


Correct Option: A
Explanation:

Monocot root vascular bundles are radial in arrangement. There are eight bundles each of xylem and phloem. Hence, the condition is described as polyarch. Xylem is described as exarch in monocot root. 

Monocot stem vascular bundles are conjoint, collateral and closed with endarch xylem. 
Dicot root vascular bundles are described as radial and tetrarch. There are four bundles each of xylem and phloem occurring alternately. Xylem is described as exarch. 
Dicot stem vascular bundles are eight in number, arranged in form of a broken ring. The vascular bundles are conjoint, collateral and open. Xylem is on the inner surface and phloem on the outer surface. Xylem is described as endarch. 

Passage cells are more distinct in endodermis of

  1. Dicot stem

  2. Monocot stem

  3. Dicot root

  4. Monocot root


Correct Option: D
Explanation:

Passage cells are endodermal cells of older roots, which have retained thin walls and Casparian strips rather than becoming suberized and waterproof like the other cells around them, to continue to allow some symplastic flow to the inside. 

Passage cells function to allow transfer of solutes, such as calcium and magnesium into the stele, in order to eventually reach the transpiration system.
Passage cells are more distinct in endodermis of monocot root and absent in dicot root, monocot stem and dicot stem. Thus, option D is correct.

Polyarch and exarch condition of found in

  1. Monocot stem

  2. Monocot root

  3. Dicot stem

  4. Dicot root


Correct Option: B
Explanation:

Monocot root vascular bundles are radial in arrangement. There are eight bundles each of xylem and phloem. Hence, the condition is described as polyarch. Xylem is described as exarch. 

Monocot stem vascular bundles are numerous in number and the xylem is endarch. 
Dicot stem vascular bundles  are eight in number, arranged in form of a broken ring. The vascular bundles are conjoint, collateral and open. Xylem is on the inner surface and phloem on the outer surface. Xylem is described as endarch. 
Dicot root vascular bundles are described as radial and tetrarch. There are four bundles each of xylem and phloem occurring alternately. Xylem is described as exarch. 

Eustele is characteristic of

  1. Monocots

  2. Dicots

  3. Pteridophytes

  4. Bryophytes


Correct Option: B
Explanation:

Eustele - In this arrangement, the primary vascular tissue consists of vascular bundles, usually in one or two rings around the pith. In addition to being found in stems, the eustele appears in the roots of monocot flowering plants. The vascular bundles in a eustele can be collateral with the phloem on only one side of the xylem or bicollateral with phloem on both sides of the xylem, as in some Solanaceae. So, eustele is the characteristic of monocots and absent in dicots, pteridophytes and bryophytes. 
Thus, the correct answer is option A.

Two cross-sections of stem and root appear similar, when viewed by naked eye. But under microscope, they can be differentiated by

  1. Exarch condition of root and stem

  2. Endarch condition of stem and root

  3. Endarch condition of root and exarch condition stem

  4. Endarch condition of stem and exarch condition of root


Correct Option: D
Explanation:

Endarch is the arrangement in which the protoxylem is directed towards the centre and metaxylem elements towards the periphery. The development of the xylems in this arrangement follows the centrifugal pattern. It is the characteristics of the stem of flowering plants. 

Whereas exarch is the arrangement in which the protoxylem is directed towards the periphery and metaxylem towards the centre. The development of the xylem in this arrangement follows the centripetal pattern. It is the characteristics of roots. Thus, option D is correct.

An example of monocot, fibre yielding plant is

  1. Cocos

  2. Corchorus

  3. Clematis

  4. Crotalaria


Correct Option: A
Explanation:

Cocos nucifera, the coconut palm, is a monocot perennial member of the Arecaceae (palm family), cultivated in tropical areas worldwide for its fruit and fiber. Coir is a natural fibre extracted from the husk of coconut and used in products such as floor mats, doormats, brushes, mattresses, etc. Coir is the fibrous material found between the hard, internal shell and the outer coat of a coconut. Other uses of brown coir are in upholstery padding, sacking and horticulture. Thus, option A is correct. 

Centripetal xylem is found in

  1. Leaf

  2. Root

  3. Dicot stem

  4. Monocot stem


Correct Option: B
Explanation:

Development of xylem from the periphery to the centre is called centripetal xylem. It is found in roots.

So, the correct option is ‘root’.

Polyarch and exarch condition is found in

  1. Monocot stem

  2. Monocot root

  3. Dicot stem

  4. Dicot root


Correct Option: B
Explanation:

Monocot root vascular bundles are radial in the arrangement. There are eight types of bundles each of xylem and phloem. Thus the condition is described as the polyarch. Xylem is detailed as an exarch.

Monocot stem vascular bundles are many in number and the xylem is the endarch.

Dicot stem vascular bundles are also eight in number but arranged in the form of a broken ring. The vascular bundles are conjoint, collateral and open. Xylem is on the inner surface and phloem on the outer surface. Xylem is described as an endarch.

Dicot root vascular bundles are described as radial and tetrarch. There are four bundles each of xylem and phloem occurring alternately. Xylem is described as an exarch.

So, the correct answer is 'Monocot root'

So, the correct answer is B.

In roots, lateral branches grow from.

  1. Epiblema

  2. Pericycle

  3. Cortex

  4. Endodermis


Correct Option: B
Explanation:

A. Epiblema – root epidermis with root hairs is called epiblema

B. Pericycle – outer most part of the stele in roots and dicot stem, produces lateral branches

C. Cortex – middle of root and dicot stem internally

D. Endodermis – inner most part of the cortex

So, the correct option is ‘Pericycle'

Passage cells occur in

  1. Monocot root

  2. Dicot root

  3. Monocot stem

  4. Aerial root


Correct Option: A,B
Explanation:

Endodermal cells without casparian strips or bands are called passage cells. These are present opposite to the protoxylem cells. These are found in both dicot root and monocot root.

So, the correct option is 'Monocot root & dicot root'.

As compared to a dicot root, a monocot root has

  1. More abundant secondary xylem

  2. Many xylem bundles

  3. Inconspicuous annual rings

  4. Relatively thicker periderm


Correct Option: B
Explanation:

The anatomy of dicot root differs from monocot root, in activity of pericycle, no. of xylem strands, presence of medulla, activity of conjunctive tissue.  

In dicot root, pericycle is involved in the formation of lateral roots and vascular cambiu, where as in monocot root, pericycle is involved in the formation of lateral roots. 
In dicot root 2 to 4 xylem strands are present in the stele, where as monocot root more than 4 xylem strands are present.
In dicot root, medulla is reduced, where as in monocot root medulla is well developed.
In dicot root, conjunctive tissue involved in the formation of vascular cambium, where as in monocot root, it is not involved in the formation of vascular cambium.
So, the correct option is 'Many xylem bundles'.

Out of the following, how many features belong to monocot root? 
1. Radial vascular bundles 
2. Closed vascular bundles
3. Endodermis absent
4. Pith developed
5. Polyarch condition

  1. One

  2. Two

  3. Three

  4. Four


Correct Option: D
Explanation:
When xylem and phloem within a vascular bundle are arranged in an alternate manner on different radii, then it is called Radial vascular bundles. It is true for monocot roots.
When there is no cambium present between the xylem and phloem elements, the bindle is said to be Closed vascular bundles.It is true for monocot roots.
Endodermis is very distinct in monocot root.Hence, sentence number 3 does not belong to the features of monocot root.
Pith is large and well developed in roots of monocotyledonous plants.
Monocot root comprises of more than six xylem bundles i.e. Polyarch condition.
So, the correct option is 'Four'

Which of the following is seen in a monocot root?

  1. Large pith

  2. Vascular cambium

  3. Endarch xylem

  4. Medullary ray


Correct Option: A
Explanation:

In monocot root, the vascular bundles are usually more than six in number. Pith is large and parenchymatous. The parenchyma of the pith become lignified and sclerenchymatous.

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