Question 1

In a dicot stem, the vascular bundles are arranged in a ______, whereas in a monocot stem they are ______:

Accepted Answer

Ring; scattered. Dicot stem bundles form a ring; monocot stem bundles are scattered in the ground tissue.

Question 2

Vascular bundles of a dicot stem are ______ (contain cambium and can grow), while those of a monocot stem are ______:

Accepted Answer

Open; closed. Dicot bundles are "open" (with cambium → secondary growth); monocot bundles are "closed" (no cambium).

Question 3

In a monocot stem, each vascular bundle is surrounded by a sheath of ______:

Accepted Answer

Sclerenchyma (bundle sheath). Monocot bundles are enclosed by a sclerenchymatous bundle sheath and are conjoint, collateral and closed.

Question 4

The xylem in a dicot stem is ______, with the protoxylem toward the centre:

Accepted Answer

Endarch. Stems have endarch xylem (protoxylem toward the pith), the reverse of roots.

Question 5

The presence of a "lysigenous cavity" (water-containing cavity) within the vascular bundle is characteristic of:

Accepted Answer

Monocot stems (e.g. maize). In monocot stems the protoxylem often has a lysigenous water cavity — a diagnostic feature (e.g. maize).

Question 6

Secondary growth (increase in girth via vascular and cork cambium) generally occurs in ______ but NOT in typical ______:

Accepted Answer

Dicot stems/roots; monocot stems. Dicots (open bundles) undergo secondary growth; typical monocots lack a vascular cambium and do not.

Question 7

Just below the epidermis of a young dicot stem lies a few layers of collenchyma. This region is the:

Accepted Answer

Hypodermis. In a dicot stem the hypodermis is collenchymatous and gives mechanical support; in a monocot stem the hypodermis is instead made of sclerenchyma.

Question 8

In a monocot stem the ground tissue is not divided into cortex, endodermis and pith. Instead it is:

Accepted Answer

Undifferentiated parenchyma throughout. A monocot stem has a continuous, undifferentiated parenchymatous ground tissue in which the vascular bundles are scattered; no separate cortex, endodermis or pith is marked out.

Question 9

The radial strips of parenchyma that run between the vascular bundles in a dicot stem, connecting the pith with the cortex, are the:

Accepted Answer

Medullary rays. In a dicot stem the parenchyma between adjacent vascular bundles forms the medullary (pith) rays, which help in radial conduction and storage.

Question 10

In both dicot and monocot stems the vascular bundles are conjoint and collateral. This means that within one bundle:

Accepted Answer

Xylem and phloem lie on the same radius with phloem outside the xylem. Conjoint collateral bundles have xylem and phloem on the same radius with phloem toward the outside; this arrangement is shared by dicot and monocot stems.

Question 11

Assertion (A): In a monocot stem the peripheral vascular bundles are smaller than those lying toward the centre. Reason (R): Each monocot bundle is surrounded by a sclerenchymatous bundle sheath. Choose the correct option:

Accepted Answer

Both A and R are true but R is not the correct explanation of A. In a monocot stem the peripheral bundles are indeed smaller than the larger centrally placed ones (A true), and each bundle does have a sclerenchymatous sheath (R true) — but the sheath is not the cause of the size difference, so R does not explain A.

Question 12

Which of the following statements about a monocot stem vascular bundle is INCORRECT?

Accepted Answer

It contains a cambium and can undergo secondary growth. Monocot stem bundles are closed (no cambium) and therefore cannot undergo normal secondary growth; they are conjoint, collateral and enclosed in a sclerenchymatous sheath.

Question 13

A student compares the hypodermis of a sunflower (dicot) stem and a maize (monocot) stem. The correct difference is that the hypodermis is:

Accepted Answer

Collenchymatous in the dicot but sclerenchymatous in the monocot. A dicot stem has a collenchymatous hypodermis (living, flexible support) whereas a monocot stem has a sclerenchymatous hypodermis (dead, rigid support).

Question 14

In the vascular bundle of a monocot stem such as maize, the water-containing cavity formed by the breakdown of the lowermost protoxylem is created by which process?

Accepted Answer

Lysigeny. The protoxylem lacuna (water-containing cavity) in a monocot bundle forms by lysigeny — the dissolution of the earliest protoxylem elements as the stem elongates.

Question 15

Which combination of features would you expect ONLY in a typical dicot stem and NOT in a monocot stem?

Accepted Answer

Vascular bundles in a ring, with cambium and a distinct pith. A dicot stem shows vascular bundles arranged in a ring, open (with cambium) and a clearly demarcated pith and cortex. Scattered closed bundles typify monocots; exarch radial bundles typify roots.

Question 16

Arrange the following tissues of a young dicot stem in order from the OUTSIDE toward the centre: (1) pith (2) epidermis (3) vascular bundle (4) cortex. The correct sequence is:

Accepted Answer

2 → 4 → 3 → 1. From the surface inward a dicot stem shows epidermis, then cortex, then the ring of vascular bundles, and finally the central pith — so the order is 2, 4, 3, 1.

Question 17

Collenchymatous hypodermis is characteristic feature of -

Accepted Answer

Dicot stem. In dicot stems the hypodermis is collenchymatous, while in monocot stems it is sclerenchymatous.

Question 18

T.S. of a material exhibits conjoint, collateral, endarch and closed bundles scattered in a ground tissue. What should be the material -

Accepted Answer

Monocot stem. Scattered, closed, conjoint, collateral, endarch bundles in ground tissue are diagnostic of a monocot stem.

Question 19

Innumerable vascular bundles, lack of cambium and lack of a well demarcated pith is found in -

Accepted Answer

Sugarcane, Grass. These are features of monocot stems, such as sugarcane and grass.

Question 20

Cortex and pith are not distinguished in -

Accepted Answer

Monocot stem. In a monocot stem the ground tissue is undifferentiated, so cortex and pith are not distinct.

Anatomy of Stems — NEET Biology MCQs with Solutions

Questions with solutions