- In dicot roots, the cork cambium originates from
(a) pit (b) hypodermis
(c) pericycle (d) endodermis. - Some of the tree trunks are found hollow at times, this is
because
(a) sapwood is susceptible to microbial attack
(b) the tracheids of heartwood get plugged by tyloses
(c) heartwood is also susceptible to attack of wood rotting
fungi
(d) heartwood is stronger and resistant to microbial
attack. - The phellem in most of the plants appear brown or dark
brown in colour as it
(a) possesses suberised walls
(b) contains abundant tannins
(c) is filled with air
(d) is composed of dead cells. - Technically the bark refers to
(a) all dead cells outside cork cambium
(b) all dead cells inner to cork cambium
(c) all cells peripheral to secondary cortex
(d) all cells outside to vascular cambium. - Secondary xylem in wood of normal dicot plants is produced
from
(a) pith and primary xylem
(b) apical meristem
(c) cork cambium
(d) vascular cambium. - Sapwood
(a) is outer functional wood of old stem
(b) is central non-functional wood of old stem
(c) is heavier and durable than heartwood
(d) comprises of dead cells only. - Which of the following is produced on inner side and on
outer side by cork cambium, respectively?
(a) Suberised cells Collenchymatous cells
(b) Dead cells Living cells
(c) Phellem Phelloderm
(d) Secondary cortex Cork - Anomalous secondary growth in monocot stem is observed
in
(a) Helianthus (b) Nerium
(c) Dracaena (d) Cucurbita. - Softwood refers to
(a) wood of herbaceous stems
(b) wood of conifers
(c) wood of dicot stem
(d) primary stem of dicots.
Exam Section
- The vascular cambium normally gives rise to
(a) primary phloem (b) secondary xylem
(c) periderm (d) phelloderm.
(NEET 2017) - Identify the wrong statement in context of heartwood.
(a) It is highly durable.
(b) It conducts water and minerals efficiently.
(c) It comprises dead elements with highly lignified walls.
(d) Organic compounds are deposited in it.
(NEET 2017) - Lenticels are involved in
(a) food transport (b) transpiration
(c) photosynthesis (d) none of the above.
(JIPMER 2017) - The balloon-shaped structures called tyloses
(a) originate in the lumen of vessels
(b) characterise the sapwood
(c) are extensions of xylem parenchyma cells into vessels
(d) are linked to the ascent of sap through xylem vessels.
(NEET Phase-II 2016) - As secondary growth proceeds, in a dicot stem, the thickness of
(a) sapwood increases
(b) heartwood increases
(c) both sapwood and heartwood increases
(d) both sapwood and heartwood remains the same.
(AIIMS 2016) - Pick out the correct statement.
(a) Spring wood is otherwise called late wood.
(b) Autumn wood is otherwise called early wood.
(c) In old trees, the heartwood is involved in the conduction
of water.
(d) In old trees, the sapwood does not conduct water.
(e) The cambial cells present between primary xylem and
primary phloem constitute the intrafascicular cambium.
(Kerala PMT 2016) - Read the different components from (i) to (iv) in the list given
below and tell the correct order of the components with
reference to their arrangement from outer side to inner side
in a woody dicot stem.
(i) Secondary cortex (ii) Wood
(iii) Secondary phloem (iv) Phellem
The correct order is
(a) (iv), (i), (iii), (ii) (b) (iv), (iii), (i), (ii)
(c) (iii), (iv), (ii), (i) (d) (i), (ii), (iv), (iii).
(AIPMT 2015)