In the given figure, which component has thin outer walls and highly thickened inner walls? [2024]
[Figure]
C
D
A
B
(1)
In a stomatal apparatus, the guard cells (component C) of stomata is characterised by thin outer walls (away from the stomatal pore) and highly thickened inner walls (towards the stomatal pore). This differential thickening allows opening and closing of stomata.
Given below are two statements: [2024]
Statement I: Parenchyma is living but collenchyma is dead tissue.
Statement II: Gymnosperms lack xylem vessels, but presence of xylem vessels is the characteristic of angiosperms.
In the light of the above statements, choose the correct answer from the options given below:
Both Statement I and Statement II are true.
Both Statement I and Statement II are false.
Statement I is true but Statement II is false.
Statement I is false but Statement II is true.
(4)
Both parenchyma and collenchyma tissues are living and simple permanent tissues. Gymnosperms lack xylem vessels.
Match List-I with List-II. [2021]
| List-I | List-II |
| (p) Cells with active cell division capacity | (i) Vascular tissues |
| (q) Tissue having all cells similar in structure and function | (ii) Meristematic tissue |
| (r) Tissue having different types of cells | (iii) Sclereids |
| (s) Dead cells with highly thickened walls and narrow lumen | (iv) Simple tissue |
Select the correct answer from the options given below:
p-(iii), q-(ii), r-(iv), s-(i)
p-(ii), q-(iv), r-(i), s-(iii)
p-(iv), q-(iii), r-(ii), s-(i)
p-(i), q-(ii), r-(iii), s-(iv)
Stomata in grass leaf are [2018]
dumb-bell shaped
kidney-shaped
rectangular
barrel-shaped
(1)
Grass being a monocot, has dumb-bell shaped guard cells. Guard cells are generally bean-shaped or kidney-shaped in dicots.
Specialised epidermal cells surrounding the guard cells are called [2016]
bulliform cells
lenticels
complementary cells
subsidiary cells
(4)
The leaf and stem epidermis of plants is covered with pores called stomata. Each stomata is surrounded by a pair of specialised epidermal cells known as guard cells, which are in some cases further surrounded by another category of less modified epidermal cells known as subsidiary cells, which provide support to the guard cells.
Vascular bundles in monocotyledons are considered closed because [2015]
there are no vessels with perforations
xylem is surrounded all around by phloem
a bundle sheath surrounds each bundle
cambium is absent
