BIOLOGY

1. SHAHINA AKTHER
GRADE 11
GULF ASIAN ENGLISH
SCHOOL

2. ANATOMY OF FLOWERING PLANTS

3. Anatomy
Study of internal organisation of
living organisms
Histology
Study of tissues & tissue system
in multicellular organisms

4. 1. TISSUE
• Group of cells, having common origin
Tissues
Meristematic Permanent
Tissue Tissues
Simple Permanent Complex
Tissues Permanent
1) Parenchyma Tissues
2) Collenchyma 1) Xylem
3) Sclerenchyma 2) Phloem

6. 2. MERISTEMATIC TISSUES
• Cells have power of division
• A. Characteristics of Meristematic Tissues
Cells are thin walled
Have abundant cytoplasm
Retain power of division
No intracellular spaces

8. B. Classification of meristems :
• Based on position in plant body
• (i) Apical meristems
• Occur at apices
• Differentiate into primary tissues
• Cause increase in length
• Axillary buds are present in axils of leaves

10. (ii) Lateral meristems :
Arranged parallel to the sides of organs of
plant
Cells produced by them differentiate
into secondary tissues
Cause increase in width of plant organ
e.g., Fascicular cambium & cork cambium

12. (iii) Intercalary meristems :
Meristems occur in between mature/permanenet
tissues
Produce cells that form primary tissues
Cause increase in length
Occur at bases of internodes & leaf sheaths of
grasses & other monocots;
They regenerate parts removed by grazing
animals

14. Based on origin
(i) Promeristems :
Group of meristematic cells in embryo /
seedlings
Give rise to primary meristems

16. (ii) Primary meristems :
Formed from promeristems
Cells produced by them differentiate
into primary / secondary permanent
tissues
e.g., Apical meristems, fascicular
cambium & intercalary meristem

18. (iii) Secondary meristems :
Formed at a later stage in
the life of plant from
permanent tissues by process
of dedifferentiation, e.g., Cork
cambium & inter-fascicular
cambium

20. 3. PERMANENT TISSUES
• Cells have lost power of division & become
structurally & functionally specialised
Characteristics :
Cells have lost power of division
Undergone differentiation into specific types for a particular function
2 types:
(i) Simple permanent tissues ( Tissue composed of 1 type of cell)
(ii) Complex permanent tissues ( Tissue is composed of more than 1
type of cell)

22. B. Simple Permanent Tissues :
(i) Parenchyma
Cells are thin- walled
Isodiametric
Retain capacity to divide at maturity
No intracellular spaces
Main function is storage
When parenchyma cells contain a number of chloroplasts they are called
chlorenchyma & when they are arranged with regular system of intercellular air
spaces, they constitute aerenchyma
Forms major component of any organ of plant

24. (ii) Collenchyma
Cells living at maturity
Cells are variously shaped
Cell wall is unevenly thickened
Occurs below epidermis of dicot stem
Cells may possess chloroplast
Provides strength & flexibility to growing organs

26. (iii) Sclerenchyma
Cells are dead at maturity
Cell wall is lignified evenly
Gives mechanical support to organs
Has 2 types of cells :
(a) SCLEREIDS (STONE CELLS) :
Oval/spherical & have very thick walls with narrow lumen
Occur in shells of nuts & in pulp of fruits & in tea leaves
(b) FIBRES :
Elongated & thick walled cells
Generally occur in groups
Present in xylem , phloem & cortex & pericycle

28. C. Complex Permanent Tissues :
(i) XYLEM :
Forms continuous channel
Concerned with transport of water & minerals
Provides mechanical support
Composed of tracheary elements, xylem parenchyma & xylem fibres
(a) XYLEM VESSELS :
Long cylindrical tubular structures formed by many cells
End walls of vessel members have either single large opening / perforation / several
small openings
Have thick lignified walls
Vessles are dead at maturity & found in angiosperms only

30. (b) XYLEM TRACHEIDS :
Elongated cells
Overlap one another at their slanting ends
Do not have perforation plates
Have thick lignified walls
Dead at maturity
(c) XYLEM PARENCHYMA ;
Thick/ thin walls of cellulose
Only living components of xylem
Involved in short distance transport
Help in storage of sugars, starch, lipids & tannins

32. (d) XYLEM FIBRES ( SCLERENCHYMA)
Dead elements
Provide mechanical support
Xylem formed in primary plant body by procambium is called primary xylem
1st formed primary xylem is called protoxylem
Later formed is called metaxylem
In stems, protoxylem lies towards pith & metaxylem towards periphery ; such
an arrangement is called endarch
In roots, protoxylem lies towards periphery & metaxylem towards pith ; such
an arrangement is called exarch
Xylem constituents formed by fascicular cambium constitue secondary xylem

34. (ii) PHLOEM
• Concerned with transport of organic
substances
• Composed of sieve elements, companion cells,
phloem parenchyma & phloem fibres

36. (a) SIEVE TUBES:
Formed by elongated sieve tube members
Cross walls have number of perforations
Mature sieve tube has peripheral cytoplasm
Functions are controlled by nucleus of companion cells
Members are characteristically present in angiosperms

38. (a) SIEVE CELLS :
Sieve areas are found to occur
throughout the end walls & lateral
walls
Cells are living, but lack nucleus
Found in lower vascular plants

40. (c) COMPANION CELLS:
Found in association with sieve tube
members
Sieve tube elements & companion
cells are connected by pit fields
Help in maintaining the pressure
gradient

42. (d) PHLOEM PARENCHYMA :
Cells are elongated & cylindrical
Have dense cytoplasm & prominent
nucleus
Stores food materials & other substances
Absent in monocot plants

44. (e) PHLOEM FIBRES (BAST FIBRES) :
Found along with other elements of phloem
Elongated & thick walled cells
Dead at maturity
Absent in primary phloem
1st formed primary phloem is known as protophloem
Later formed is known as metaphloem
Elements formed by fascicular cambium constitute secondary
phloem

46. TISSUE SYSTEM IN PLANTS
• 3 tissue sysytems:
(i) Epidermal tissue system
(ii) Vascular tissue system
(iii) Ground/ fundamental tissue system

48. (i) EPIDERMAL TISSUE SYSTEM
• Forms outermost covering of plant body
• Consists of epidermal cells, epidermal appendages &
stomata
• Epidermis is outermost layer
• Epidermis is single-layered
• Each cell has small amount of cytoplasm & large
vacuole
• Outer surface is covered with thick layer
• Cuticle prevents loss of water from aerial part of plants
• Epidermis is interrupted by small pores called stomata
• Stoma is surrounded by 2 guard cells

50. • Guard cells are bean-shaped in dicot plants & dumb bell in
monocots
• Outer wall is thin & inner wall is thick
• They possess chloroplasts & carry out photosynthesis
• Epidermal cells in their vicinity become specialised in their size
& shape
• Stomatal apparatus – stomatal aperture, guard cells &
surrounding epidermal cells
• Epidermis also bears appendages
• Root hairs are unicellular elongation of epidermal cells of the
root
• Appendages on stem epidermis are called trichomes
• Help in preventing water loss by transpiration
• Glandular/ secretory in many plants

52. (ii)VASCULAR TISSUE SYSTEM
• Includes xylem & phloem
• They occur as discrete strands called vascular
bundles
• Occur along same radius, vascular bundle is
called collateral
• When strip of cambium is present b/w xylem
& phloem – open vascular bundle
• No cambium in vascular bundle – closed
vascular bundle

54. • 2 phloem poles occur in a vascular bundle ,
separated from central xylem – bicollateral
vascular bundle
• Xylem & phloem occur along different radii,
alternating with each other – radial bundle
• When protoxylem is towards periphery &
metaxylem is towards centre – exarch
• When protoxylem is towards centre &
metaxylem is towards periphery - endarch

56. (iii) GROUND TISSUE SYSTEM
• Ground tissue – all tissues except epidermis &
vascular bundles
• Consists of simple permanent tissues
• Parenchyma cells present in cortex, pericycle;
pith & medullary rays
• Ground tissue in leaves - mesophyll

58. My special thanx goes to my
biology teacher Mrs Alermelu
Natchair who gave and confirmed
this permission and encouraged me
to go ahead.