NEET Practice Questions (MCQs) with Answers & Solutions

According to the NCERT text, 'In dicotyledonous stems, cambium is present between phloem and xylem. Such vascular bundles because of the presence of cambium possess the ability to form secondary xylem and phloem tissues, and hence are called open vascular bundles. In the monocotyledons, the vascular bundles have no cambium present in them. Hence, since they do not form secondary tissues they are referred to as closed.'

The NCERT text states: 'The monocot stem has a sclerenchymatous hypodermis, a large number of scattered vascular bundles, each surrounded by a sclerenchymatous bundle sheath, and a large, conspicuous parenchymatous ground tissue...The phloem parenchyma is absent, and water-containing cavities are present within the vascular bundles.' These features collectively identify a monocot stem.

The NCERT states for dicot root: 'The pith is small or inconspicuous.' For monocot root, it says: 'Pith is large and well developed.'

The NCERT states for isobilateral (monocotyledonous) leaf: 'In an isobilateral leaf, the stomata are present on both the surfaces of the epidermis; and the mesophyll is not differentiated into palisade and spongy parenchyma.' In contrast, for dorsiventral (dicotyledonous) leaf, it says: 'The abaxial epidermis generally bears more stomata than the adaxial epidermis. The latter may even lack stomata. ...Mesophyll... has two types of cells – the palisade parenchyma and the spongy parenchyma.'

The NCERT states: 'As compared to the dicot root which have fewer xylem bundles, there are usually more than six (polyarch) xylem bundles in the monocot root.' For dicot root, it mentions 'There are usually two to four xylem and phloem patches.'

The NCERT text on monocotyledonous stem states: 'a large number of scattered vascular bundles... Peripheral vascular bundles are generally smaller than the centrally located ones.'

The NCERT states for dorsiventral (dicotyledonous) leaf: 'Mesophyll... has two types of cells – the palisade parenchyma and the spongy parenchyma.' Therefore, the statement that mesophyll is undifferentiated in dicot leaves is incorrect.

The NCERT describes bulliform cells: 'When the bulliform cells in the leaves have absorbed water and are turgid, the leaf surface is exposed. When they are flaccid due to water stress, they make the leaves curl inwards to minimise water loss.'

The NCERT states: 'The monocot stem has ... a large number of scattered vascular bundles, each surrounded by a sclerenchymatous bundle sheath...'

For dicot root: 'The outermost layer is epiblema. Many of the cells of epiblema protrude in the form of unicellular root hairs.' For monocot root: 'It has epidermis [epiblema]...'. Both primary roots will have epiblema and root hairs. Monocot roots lack secondary growth, but dicot roots do undergo secondary growth. Pith size and xylem bundle numbers differ.