CBSE Questions for Class 11 Medical Biology Anatomy Of Flowering Plants Quiz 17 - MCQExams.com

a) Collenchymatous hypodermis -applicable because hypodermis is made up of collenchyma.

b) Polyarch xylem – not applicable, because, xylem and phloem are present on the same radius and side by side. It is found in monocot roots.

c) Presence of Casparian strips on endodermis – not applicable, because Casparian strips appear on the radial and tangential walls of the endodermis of roots.

d) Open vascular bundle – applicable, because, cambium is present between the xylem and phloem in the vascular bundles.

e) Presence of medullary rays – applicable – because, these are the extensions of medulla between the vascular bundles.

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.

The inner most part of the cortex in root and dicot stem is endodermis. it is single layered. Cells are barrel shaped and thick walled. On the radial walls and tangential walls, ligno suberised thickenings are present. These are called Casparian thickenings. Some of the endodermal cells lack casparian bands. These are called passage cells. These cells are present opposite to the protoxylem cells. Endodermis acts as check point, and prevents the outflow of water and minerals from the stele into cortex, and also acts as a barrier in the inflow of water and mineral from cortex and stele.

The anatomy of dicot root and dicot stem differ in many characters. In dicot, root epidermis contains root hairs, whereas in epidermis contains trichomes, cuticle and stomata. In dicot, root cortex shows general cortex and endodermis, whereas in dicot stem cortex shows hypodermis, general cortex and endodermis.

In dicot, root hypodermis is absent whereas, in dicot stem, hypodermis is present.

In dicot root endodermis shows Casparian bands, whereas in dicot stem endodermis contains starch grains in its cells.

In dicot root pericycle is parenchymatous, take part in the lateral formation and secondary growth, whereas in dicot stem, pericycle is discontinuous, sclerenchymatous, present in the form of patches over the vascular bundles.

In dicot root, vascular bundles are radial, whereas in dicot stem vascular bundles are collateral, conjoint, open

In dicot, root xylem is exarch, whereas in dicot stem xylem is endarch.

In dicot, root medulla is reduced, whereas in dicot stem is xylem is endarch.

In dicot root, conjunctive tissue is present, whereas, in dicot stem, medullary rays are present.

Correct Answer: B

Explanation:

• The vegetative shoot apex is the primary region for the growth of the shoot region of the plant. It will show the production of new leaves at a fixed time intervals and this process is termed as Plastochron.
•  Leaf primordium is the area including the group of cells below the shoot apex which develops into a leaf.
• The shoot apical meristem is the site that contains small cellular outgrowths, called leaf primordial, and the junction where the leaf and stem meet is known as an axillary bud. Also, we will see that at the tip of the shoot apex a terminal bud is found.

Hence, the correct option is A-Leaf Primordium, B- Shoot Apical Meristem, C- Axillary Buds.

$$\textbf{Correct option: }$$

$$\textbf{Explanation for correct statements:}$$

Statement A:

$$\bullet$$ The monocots do not have a single vascular bundle like in dicots. There are many vascular bundles that are present in scattered forms.

$$\bullet$$ Vascular bundles help in the transportation of various substances from one part to another part of the plant.

$$\bullet$$ Vascular bundles are made up of two types of tissues which are xylem and phloem. Xylem conducts water and minerals from the root to shoot whereas phloem tissue conducts food from leaves to all parts of the plant.

Statement B:

$$\bullet$$ Hypodermis is the cellular layer present below the epidermis layer. the cells of the hypodermis layer are modified to provide mechanical strength to the plant.

$$\bullet$$ The hypodermal cells of the monocot stem are sclerenchymatous which have thick cell walls due to the deposition of lignin. These cells provide strength to the stem.

Statement D:

$$\bullet$$ The core part of a stem or root is called stele.

$$\bullet$$ Stele is atactostele i.e. conjoint, collateral, and closed.

$$\textbf{Explanation for incorrect statement:}$$

Statement C:

$$\bullet$$ Endodermis is mostly absent in the monocot stems, but sometimes it is present around the scattered vascular bundles which is not well-developed.

Hence the correct option is option A i.e. only (a), (b) and (d) statements are correct..

• Collenchymatous hypodermis is a characteristic feature of dicot stem. 
• Vascular bundles are arranged in a ring with pith concentrated at the core of the stem. 
• The type of vascular bundle found in the dicot stem is conjoint and open type. 
  
• Phloem parenchyma is present in dicot and absent in monocotyledons.