Bulliform cells are responsible for [2024]
inward curling of leaves in monocots
protecting the plant from salt stress
increased photosynthesis in monocots
providing large spaces for storage of sugars
(1)
Bulliform cells are large, empty, and colourless cells which are found in leaves of monocots, e.g., grasses. During water stress, these cells become flaccid and make the leaves curl inwards to minimise water loss.
The transverse section of a plant part showed polyarch, radial and exarch xylem, with endodermis and pericycle. The plant part is identified as [2023]
monocot root
dicot root
dicot stem
monocot stem
(1)
Monocot roots have more than six xylem bundles (polyarch), while dicot roots have 2-4 vascular bundles (diarch to tetrarch). Radial and exarch vascular bundle is a characteristic feature of both monocot and dicot roots.
The transverse section of a plant shows the following anatomical features: [2020]
(i) Large number of scattered vascular bundles surrounded by bundle sheath
(ii) Large conspicuous parenchymatous ground tissue
(iii) Vascular bundles conjoint and closed
(iv) Phloem parenchyma absent
Identify the category of plant and its part.
Monocotyledonous stem
Monocotyledonous root
Dicotyledonous stem
Dicotyledonous root
Grass leaves curl inwards during very dry weather. Select the most appropriate reason from the following. [2019]
Tyloses in vessels
Closure of stomata
Flaccidity of bulliform cells
Shrinkage of air spaces in spongy mesophyll
(3)
In grasses, certain adaxial epidermal cells along the veins modify themselves into large, empty, colourless cells. These are called 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.
In the dicot root the vascular cambium originates from [2019]
tissue located below the phloem bundles and a portion of pericycle tissue above protoxylem
cortical region
parenchyma between endodermis and pericycle
intrafascicular and interfascicular tissue in a ring
Casparian strips occur in [2018]
epidermis
pericycle
cortex
endodermis
(4)
Casparian strip is a band of thickening present on the radial and tangential walls of the endodermis. It is made up of both suberin and lignin.
Root hair develop from the region of [2017]
elongation
root cap
meristematic activity
maturation
(4)
Root hair are lateral tubular outgrowths that develop from the outer cells of the zone of maturation or root hair zone.
Cortex is the region found between [2016]
epidermis and stele
pericycle and endodermis
endodermis and pith
endodermis and vascular bundle
A major characteristic of monocot root is the presence of [2015]
vasculature without cambium
cambium sandwiched between phloem and xylem along the radius
open vascular bundles
scattered vascular bundles
(1)
In monocot root, a large number of vascular bundles are arranged in the form of a ring around the central pith. Vascular bundles are closed because there is no cambium present between the xylem and phloem.
You are given a fairly old piece of dicot stem and a dicot root. Which of the following anatomical structures will you use to distinguish between the two? [2014]
Secondary xylem
Secondary phloem
Protoxylem
Cortical cells
(3)
In stems, the protoxylem lies towards the centre (pith) and the metaxylem lies towards the periphery. This type of primary xylem is called endarch. In roots, the protoxylem lies towards the periphery and the metaxylem lies towards the centre; such arrangement is called exarch.
