Tag: internal structure of root(dicot and monocot)

Questions Related to internal structure of root(dicot and monocot)

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