12Plant tissue

📚
MERISTEMATIC TISSUE
▢ Definition of Meristematic Tissue:
  • •
    A group of young, immature, and undifferentiated cells that are actively dividing or retain the power of continuous cell division.
  • •
    These cells are responsible for the growth and development of the plant body.
  • •
    They are typically located at the growing regions of the plant, such as root and shoot apices.
▢ Features of Meristematic Tissue:
    Image 1
  1. Composed of immature, undifferentiated cells with continuous power of division
  2. Cells are small, isodiametric, spherical, oval, or polygonal in shape
  3. Cell wall is thin, elastic, and made up of cellulose
  4. Dense cytoplasm with a prominent, large nucleus
  5. Vacuoles are generally absent; if present, they are very small
  6. Intercellular spaces are absent; cells are compactly arranged
  7. High metabolic activity and rate of respiration
  8. Plastids are present in the form of proplastids
  9. Ergastic substances (non-living cell inclusions) are absent
▢ Types:
Image 1
Fig.Types of meristematic tissue based on position

Table 1: Types of meristematic tissue

Feature
Apical meristem
Intercalary meristem
Lateral / Radial meristem
Position
Apices of root + shoot
Between two permanent tissues; base of internode; base of leaves
Lateral sides
Function
Increase in length
Increase in length
Increase in girth / diameter
Consumption
Not consumed up
Consumed up
Examples / Notes
◉ Points:
  • •
    Leaf primordia → leaf
  • •
    Axillary bud + terminal bud derived from apical meristem activity
Grasses → growth by intercalary meristem
Cambium-like activity → radial growth
Special points
◉ Points:
  • •
    Pteridophytes → single cell
  • •
    Phanerogams → group of cells
▢ Apical Meristem Division by Haberlandt:
Image 1

Table 1: Haberlandt’s zones

Zone
Tissue system formed
Protoderm
Epidermal tissue system
Ground meristem
Ground tissue system
Procambium
Vascular tissue system
▢ Shoot Apex Organization:
❖ Apical Cell Theory:
Image 1

Table 1: Apical cell theory

Point
Data
Proposed by
Nageli
Concept
Single pyramidal cell → entire growth by division + redivision
Applicable to
Bryophytes, vascular cryptogams / pteridophytes, some higher algae
Not applicable to
Gymnosperms, angiosperms
❖ Histogen Theory:
Image 1

Table 1: Histogen theory of shoot apex

Histogen
Position
Gives rise to
Dermatogen
Outermost
Epidermis
Periblem
Middle
Cortex including endodermis
Pleurome
Innermost
Vascular bundle including pith
Proposed by Hanstein; 3 groups of initials in shoot apex
❖ Tunica-Corpus Theory:
Image 1

Table 1: Tunica-corpus theory

Region
Position
No. of layers
Division
Tissue formed
Tunica
Outer region
Generally 1
Anticlinal
Epidermis
Corpus
Inner mass
Several
Anticlinal + periclinal
Bulk of adult plant
Proposed by Schmidt; most accepted theory
◉ Anticlinal vs Periclinal Division:

Table 1: Division plane

Division
Plane
Effect
Anticlinal division
Perpendicular to surface
Surface area increases
Periclinal division
Parallel to surface / tangential cleavage
Layers increase → girth increases
▢ Root Apex Organization:
❖ Apical Cell Theory:

Table 1: Apical cell theory of root apex

Point
Data
Proposed by
Nageli
Concept
Single apical cell in root apex → entire growth
Applicable to
Pteridophytes, gymnosperms
Not applicable to
Angiosperms
❖ Histogen Concept:
Image 1

Table 1: Histogen concept of root apex

Histogen
Gives rise to
Dermatogen
Epiblema / piliferous layer / rhizodermis + root cap in dicot
Periblem
Cortex including endodermis
Pleurome
Vascular tissue including pith
Calyptrogen
Root cap in monocot
Proposed by Hanstein; 4 groups of initials in root apex
❖ Quiescent Centre Concept:
Image 1

Table 1: Quiescent centre

Point
Data
Given by
Clowes in maize
Meaning
Inactive centre in root apex
Biochemical status
Low DNA, RNA, protein
Cell cycle status
G₀ phase
Function
Reserve for replenishment of damaged meristem cells
Hormonal note
Some auxin synthesis
📚
PERMANENT TISSUE
▢ Definition:
  • •
    Formed by division + differentiation of meristematic tissue
  • •
    Fully mature + developed + differentiated cells
  • •
    Lost power of division
  • •
    May be living/dead
  • •
    May be thin-walled/thick-walled
  • •
    Generally thin-walled = living; thick-walled = dead
📖
Simple permanent tissue
▢ General Features:
  • •
    Made up of one type of cells
  • •
    Similar function
  • •
    Homogeneous group
📝
Parenchyma
Image 1
▢ Features:
  • •
    Isodiametric cells
  • •
    Thin-walled
  • •
    Living
  • •
    Abundant intercellular spaces
  • •
    Most abundant permanent tissue
  • •
    Evolved first
  • •
    Fundamental tissue → other tissues evolved from it
  • •
    Cell wall → cellulose + calcium pectate
  • •
    Main function → food storage
▢ Special Types:

Table 1: Special types of parenchyma

Type
Occurrence
Function / Note
Prosenchyma
Pericycle of some plants
Rigidity + strength
Aerenchyma
Hydrophytes
Floating + buoyancy
Chlorenchyma
Mesophyll of leaves
Photosynthesis
Palisade + spongy parenchyma
Dicot leaves only
Mesophyll differentiation
Idioblastic / storage parenchyma
Special storage cells
Contains enzymes, resin, ergastic substances
📝
Collenchyma
Image 1
▢ Features:
  • •
    Thick-walled but living cells
  • •
    Living mechanical tissue
  • •
    Cell wall thickening at corners/angles
  • •
    Thickening due to pectin + cellulose; mainly pectin
  • •
    Pectin → holds large amount of water
  • •
    Simple pits between adjacent collenchyma cells
  • •
    Absent in dicot roots + monocots
  • •
    Forms hypodermis in herbaceous dicot stem + woody climber / liana
▢ Types:
Image 1

Table 1: Types of collenchyma

Type
Angular collenchyma
Lacunar / tubular collenchyma
Lamellar collenchyma
Intercellular space
Absent
Present
Absent
Special point
Most common + most abundant
Thickening around intercellular spaces
Wall thickening in layers
📝
Sclerenchyma
Image 1
▢ Features:
  • •
    Dead cells
  • •
    No protoplasm
  • •
    Thick-walled
  • •
    Cell wall lignified
  • •
    Lignin → hardest plant tissue; maximum rigidity
  • •
    Bears compression, pull, bending, shearing forces
  • •
    Simple + bordered pits in sclerenchyma fibres
▢ Fibre Note:

Table 1: Commercial fibre composition

Fibre
Rich in
Cotton
Cellulose
Flax
Cellulose
Jute
Lignin
Coir
Lignin
▢ Common Occurrence:
  • •
    Hypodermis of monocot stem
  • •
    Pericycle
  • •
    Xylem
  • •
    Phloem
▢ Types:
  1. Sclerenchyma Fibres
  2. Sclereids / Stone Cells / Grit Cells
Image 1
📄
Sclerenchyma Fibres
  • •
    Elongated
  • •
    Tapering at both ends
  • •
    Spindle-shaped
  • •
    Commercial fibres = sclerenchyma fibres
  • •
    Directly derived from meristematic cells
📄
Sclereids / Stone Cells / Grit Cells
▢ Features:
  • •
    Derived by secondary thickening of parenchymal cells
  • •
    Shorter
  • •
    Highly thickened
  • •
    Narrow cavities
  • •
    Hard seed coat due to stone cells
  • •
    Stone cells in fruit pulp of Pyrus
▢ Occurrence:
    Image 1
  1. Endocarp of coconut
  2. Hard seed coats
  3. Fruit pulp of guava
  4. Fruit pulp of pear
▢ Types by Shape:

Table 1: Types of sclereids

Type
Shape
Occurrence
Brachysclereids / stone cells
Irregular
Pulp of pear, guava; endocarp of coconut fruit
Macrosclereids
Rod-shaped
Hard seed coat of Leguminosae
Osteosclereids
Bone-shaped
Subepidermis of legume seeds
Astrosclereids
Star-shaped
Tea leaves; petiole of lotus
📖
Complex permanent tissue
Secondary xylem = wood
📝
Xylem / Hadrome
Image 1
▢ Definition: Complex tissue made up of more than one type of cells/elements
▢ Elements:

Table 1: Xylem elements

Element
Special point
Vessels / trachea
Absent in pteridophytes + gymnosperms
Tracheids
Water conduction + support
Xylem parenchyma
Living storage element
Xylem fibres / wood fibres
Mechanical support
📝
Phloem / Leptome
Image 1
▢ Elements:

Table 1: Phloem elements

Element
Occurrence / Note
Sieve elements
Sieve cells + sieve tubes
Sieve cells
Pteridophytes + gymnosperms
Sieve tubes
Angiosperms
Albuminous cells
Pteridophytes + gymnosperms
Companion cells
Angiosperms
Phloem parenchyma
Storage + lateral conduction
Phloem fibres / bast fibres
Mechanical support
Q1.
Vessels in plants are generally blocked by:  [IOM 2005]
📅IOM 2005
Q2.
The vascular bundle having phloem in the centre and surrounded by xylem is termed as: [IOM 2004]
📅IOM 2004
Q3.
Which of the following shows the secondary growth: [IOM 2003]
📅IOM 2003
Q4.
Stele in monocot stem is:  [IOM 1998]
📅IOM 1998
Q5.
Intercalary meristem is a portion of:  [IOM 1997]
📅IOM 1997
Q6.
Which one of the following is a living component of xylem system?  [IOM 1997]
📅IOM 1997
Q7.
Lateral roots originate from:  [IOM 1996]
📅IOM 1996
Q8.
The xylem in root is:   [IOM 1999]
📅IOM 1999
Q9.
The leaves of grasses roll because:  [BPKIHS 2001]
📅BPKIHS 2001
Q10.
Exarch xylem has:    [BPKIHS 2001]
📅BPKIHS 2001
Q11.
A meristem responsible for extra-stellar secondary growth in dicot stem is
Q12.
Food is transported to different parts of plant through:   [BPKIHS 2004]
📅BPKIHS 2004
Q13.
Secondary growth in thickness of plants is brought about initially by division of the:  [BPKIHS 2005]
📅BPKIHS 2005
Q14.
Bidirectional translocation of mineral takes place in:  [BPKIHS 2006]
📅BPKIHS 2006
Q15.
Cambium helps in  [MOE 2063]
📅MOE 2063
Q16.
Function of sclerenchyma tissue is to  [MOE 2063]
📅MOE 2063
Q17.
The hypodermis in monocotyledonous stem is  [MOE 2062]
📅MOE 2062
Q18.
Which of the following is an example of primary meristematic tissue?  [MOE 2062]
📅MOE 2062
Q19.
Bicollateral vascular bundles are found in  [MOE 2060]
📅MOE 2060
Q20.
The vascular bundle is scattered in  [MOE 2003]
📅MOE 2003
Q21.
Lateral roots arise from    [MOE 2002]
📅MOE 2002
Q22.
Vascular bundle in maize is       [MOE 2058]
📅MOE 2058
Q23.
The youngest layer of secondary xylem in a woody stem is located just  [MOE 2000, 2055]
📅MOE 2000, 2055
Q24.
Cambium of dicot root is formed by     [MOE 2000]
📅MOE 2000
Q25.
If metaxylem faces towards pith, the xylem is  [MOE 2059]
📅MOE 2059
Q26.
Vascular bundle of dicot stem is       [MOE 2055]
📅MOE 2055
Q27.
Periderm consists of     [MOE 2054]
📅MOE 2054
Q28.
Net-like thickening of xylem vessel is called   [MOE 2054]
📅MOE 2054
Q29.
Pith is well developed in       [BPKIHS 1994]
📅BPKIHS 1994
Q30.
In grafting, stock and scion following ought to be joined   [BPKIHS 1994]
📅BPKIHS 1994
Q31.
Chlorenchyma and aerenchyma are modified forms of   [BPKIHS 1995]
📅BPKIHS 1995
Q32.
With increasing secondary growth in trees which will increase in diameter?  [BPKIHS 1995]
📅BPKIHS 1995
Q33.
Amyloplast is  [BPKIHS 1990]
📅BPKIHS 1990
Q34.
Pith is developed by the activity of [BPKIHS 1997]
📅BPKIHS 1997
Q35.
Mesophyll tissue found in leaves are actually the [BPKIHS 1997)
📅BPKIHS 1997)
Q36.
Atactostele is present in [BPKIHS 1998)
📅BPKIHS 1998)
Q37.
Jute is a   [BPKIHS 1998, IOM 2059]
📅BPKIHS 1998, IOM 2059
Q38.
Suberin in a dead cork cell   [BPKIHS 2004]
📅BPKIHS 2004
Q39.
Name the condition in which xylem is surrounded in both outer and inner sides by phloem. [IOM 2007]
📅IOM 2007
Q40.
Hypodermis in monocotyledonous stem is [IE 2003]
📅IE 2003
Q41.
Casparian strip is found in     [IE 2004)
📅IE 2004)
Q42.
Cork & secondary cortex is formed due to [IE 2005)
📅IE 2005)
Q43.
Most common ground tissue [IE 2005)
📅IE 2005)
Q44.
Both the palisade & spongy mesophylls of leaf function to: [IE 2007]
📅IE 2007
Q45.
Cork tissue is known as:   [IE 2008]
📅IE 2008
Q46.
The pericycle which gives rise to lateral roots consist of:  [IE 2009]
📅IE 2009
Q47.
A phellogen originates from   [IE 2009]
📅IE 2009
Q48.
B. The protoxylem is largely composed of   [IE 2009]
📅IE 2009
Q49.
Primary growth involves activity of the [IE 2009]
📅IE 2009
Q50.
Protoxylem and stomata in a dorsiventral leaf are present, respectively [I.E.]
📅I.E.
Q51.
When the bark of a tree is removed, the plant die due to [BPKIHS - 2016]
📅BPKIHS - 2016
Q52.
In plant, phloem helps in   [BPKIHS - 2015]
📅BPKIHS - 2015
Q53.
Histogen theory was proposed by [BPKIHS - 2014]
📅BPKIHS - 2014
Q54.
Collateral vascular bundle is [BPKIHS - 2014]
📅BPKIHS - 2014
Q55.
Which layer gives rise to stele? [BPKIHS - 2013]
📅BPKIHS - 2013
Q56.
Cambium is not found in   [BPKIHS - 2013]
📅BPKIHS - 2013
Q57.
Phloem helps in   [BPKIHS - 2012]
📅BPKIHS - 2012
Q58.
The study of determining age of studying annual ring     [BPKIHS - 2012]
📅BPKIHS - 2012
Q59.
Which is responsible for the growth in circumference of stem or root? [BPKIHS - 2011]
📅BPKIHS - 2011
Q60.
The ballon like growth of parenchyma in lumen of a vessel is known as  [BPKIHS - 2011]
📅BPKIHS - 2011
Q61.
Cohesion and tension theory in transpiration of plant was given by  [BPKIHS - 2011]
📅BPKIHS - 2011
Q62.
Cricket ball is made from  [BPKIHS - 2011]
📅BPKIHS - 2011
Q63.
Grafting will be possible in monocot plant if only it has   [BPKIHS - 2011]
📅BPKIHS - 2011
Q64.
Protoderm is a part of   [IOM-2014]
📅IOM-2014
Q65.
The study of growth rings of tree in relation to climate is called [IOM-2014]
📅IOM-2014
Q66.
Jute fibre is obtained from [IOM-2016]
📅IOM-2016
Q67.
Annual rings helps in determining  [IOM-2016]
📅IOM-2016
Q68.
Which of the following is a dual complex tissue?  [IOM-2012]
📅IOM-2012
Q69.
Trachea, tracheids, wood parenchyma and vessels are  present in  [IOM-2012]
📅IOM-2012
Q70.
Jute fibre is obtained from  [IOM-2012]
📅IOM-2012
Q71.
Which of the following monocot shows secondary  growth?  [MOE 2014]
📅MOE 2014
Q72.
What type of vascular bundle is found in dicot stem? [MOE 2014]
📅MOE 2014
Q73.
Growth rings in dicot stem are formed due to the activity of  [MOE 2013)
📅MOE 2013)
Q74.
Which one of the following tissue is found only on  dicot plants? [MOE 2010)
📅MOE 2010)
Q75.
Casparian stripes is found in  [MOE 2010)
📅MOE 2010)