Tag: internal structure of stem(dicot and monocot)

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

Y- shaped arrangement of xylem vessles is found in

  1. monocot stem

  2. dicotstem

  3. monocot root

  4. dicot root


Correct Option: A
Explanation:

Xylem comprises of vessels, tracheids, xylem parenchyma, and restricted xylem strands.  the vessel is Y-molded with bigger two round set metaxylem vessels shaping the arms and littler yearly or winding protoxylem vessels, framing the base.

So, the correct option is 'monocot stem'.

The number of growth rings (sum of the rings of spring wood and autumn wood) in the year 2000 is found to be 20. What will be the number of annual rings in 2018?

  1. 38

  2. 8

  3. 28

  4. 18


Correct Option: A
Explanation:

Every year one spring ring and one autumn rings make one annual ring which is used to estimate the age of the plant.

Hence the number of rings present in 2000=20
Therefore, the number of rings present in 2018=20+18
That is equal to 38 rings after 18 years.
So the correct option is '38'

Read the following statements and select the correct  option.
A. Damage to chordae tending of semilunar valves in aorta causes back flow of blood in left ventricle.
B. Closure of atrio-ventricular valves during ventricular systole generates first heart sound

  1. Both statements are correct

  2. Only statement B is correct

  3. Only statement A is correct

  4. Both statements are incorrect.


Correct Option: A
Explanation:

The semilunar valves are present inbetween the aorta and the left ventricle (aortic semilunar valve) and between the right ventricle and the pulmonary artery (pulmonary semilunar valve). The aortic semilunar valve functions to pevent backflow of blood into the ventricle. Damage to chordae tendinae of the aortic semilunar valve will therefore cause backflow of blood to the left ventricle. The first heart sound is produced by the closure of the mitral and the tricuspid valve, that are the atrioventricular valves. 

So, the correct option is 'Both statements are correct'.

In a monocot stem, the vascular bundles are?

  1. Arranged in a ring

  2. Arranged alternatively

  3. Present inside endodermis

  4. Scattered in ground tissue


Correct Option: D
Explanation:
In a monocot stem, a large number of vascular bundles lie scattered throughout the ground tissue and peripheral bundles are generally smaller than the centrally located ones. The vascular bundles are conjoint, collateral but closed.

So, the correct answer is 'Scattered in ground tissue'.

In monocot stem


(a) Vascular bundles are scattered.
(b) Hypodermis is sclerenchymatous.
(c) Endodermis is well developed.
(d) Stele is atactostele.

  1. Only (a) and (b), (d) are correct

  2. Only (c) and (d) are correct

  3. Only (b) is incorrect

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


Correct Option: A
Explanation:

Vascular tissue system composed of vascular bundles and they are scattered. So, the steles are called atactostele. Hypodermis is multilayered and sclerenchymatous. Endodermis is not developed.

So, the correct option is 'a, b, d are correct'.

Select the mismatched pair.

  1. Collateral and open vascular bundles- Sunflower stem

  2. Bicollateral vascular bundles - Maize stem

  3. Concentric vascular bundles - Ferns

  4. Radial vascular bundle - Maize root


Correct Option: B
Explanation:
A. Collateral open vascular bundles- Xylem is present in the inner side and phloem to the outside and cambium ring is present in between them.
Eg- in dicot stems as in sunflower stem.
B. Bicollateral vascular bundles- one patch of xylem and two patches of cambium are present.
Eg- plants belonging to the family Cucurbitaceae, Solanaceae etc
Mazie belongs to the family Gramineae.
C. Concentric vascular bundles- in which either the xylem or phloem surrounds each other.
Eg- ferns.
D. Radial vascular bundle- Xylem and phloem occupy different radii and alternate each other.
Eg- Dicot and monocot roots (as in maize root).
So, the correct answer is 'Bicollateral vascular bundles - Maize stem'.

Plants have evolved various defences to lessen the impact of predation by herbivores. Choose the correct option for the defence measures in the given plants. Where M-Morphological, C-Chemical, A-Anatomical, P-Physiological.

Acacia Cactus Calotropins
$(1)$ P P M
$(2)$ A M C
$(3)$ P C C
$(4)$ M M C
  1. A

  2. B

  3. C

  4. D


Correct Option: A

Which type of vascular bundle is found in monocot stem?

  1. Conjoint, collateral, open, endarch

  2. Radial, open, diarch

  3. Radial, open, mesarch

  4. Conjoint, collateral, closed, endarch


Correct Option: A

Read the following features and choose the correct option about anatomy of dicot and monocot stem.
(i) Collenchymatous hypodermis.
(ii) Vascular bundles are scattered.
(iii) Eustele.
(iv) Ground tissue is not differentiated.
(v) Pericycle absent

  1. Dicot stem i,ii,iii ; Monocot stem iv,v

  2. Dicot stem i,ii,v ; Monocot stem iii,iv

  3. Dicot stem iii, v; Monocot stem i,ii,iv

  4. Dicot stem i,iii ; Monocot stem ii, iv, v


Correct Option: A
Explanation:
Dicot stem has collenchymatous hypodermis, monocots have sclerenchymatous hypodermis.  In each vascular bundle, the xylem and phloem are separated by a substance called vascular cambium. Eustele is similar to the dictyostele except that the bundles lack an endodermis and are collateral. 
Monocots have vascular bundles throughout their ground tissue, their stems do not have a discernible pith; the parenchyma cells in monocot stems are referred to simply as ground tissue. In monocot roots, the pericycle present only produces the lateral roots. 
So the correct option is 'Dicot stem i,ii,iii ; Monocot stem iv,v'.

Conjoint, collateral, closed and endarch vascular bundles scattered in the ground tissue are found in

  1. Dicot root

  2. Monocot root

  3. Dicot stem

  4. Monocot stem


Correct Option: D
Explanation:

Conjoint, collateral, closed and endarch vascular bundles scattered in the ground tissue are found in monocot stem. In a monocotyledenous stem 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.