STPM Form 6 Chemistry Solids

1. TISSUES AND ORGANS

2. PLANT TISSUES

3. Plant tissues
Meristemic Permanent
Vascular
tissues tissues
Ground
Apical Lateral Intercalary Epidermal Supporting Xylem Phloem
Parenchyma
Epidermis Periderm Collenchyma Sclerenchyma

4. MERISTEMIC TISSUES
 Small
 Living tissues
 Unspecialised
 Dividing - Mitosis
 Large nuclei, Dense cytoplasm with small vacuoles
 Become specialized when matured
 Embryonic meristem do not stop dividing throughout
the entire lifespan
 Only found in certain areas

5. TYPES OF MERISTEMIC TISSUES
• Root tips
• Shoot tips
Apical • Primary growth – increase length
• At nodes
• Monocots
Intercalary • Grow quicker after being cut
• Also called cambium
• Secondary growth – increase diameter
• Vascular cambium – secondary xylem & phloem
Lateral • Cork cambium – For outer cork layer + suberin – Reduce evaporation

14. GROUND TISSUES
PARENCHYMA CELLS
 Living tissue
 Contain
cellulose, hemicellulose, pectin
 Secondary cell wall absent
 Permeable to water and solutes
 Large vacuoles, Thin cytoplasm
 Food storage - Apple
 Water reserve
 Support & Shape for Herbaceous
plants
 Large air space for Photosynthesis
 Palisade mesophyll
 Sponge mesophyll

15. PARENCHYMA

16. UNSPECIALISED PARENCHYMA
GROUND TISSUE
 Fruits, Roots, Stem, Leaves
 In herbaceous plants
 Spherical & Thin-walled
 Large vacuole
 Thin primary wall, without
secondary walls
 Turgid cells
 Provide support

17. SPECIALISED PARENCHYMA CELLS
Epidermis Mesophyll cells
 Elongated and flattened
 Palisade mesophyll
 Secrete cutin - Waxy
cuticle  Compact cells with
 Protective barrier chloroplast
 Water loss  Spongy mesophyll
 Bacteria
 Loose cells with fewer
chloroplast
 Form stomata
 Gaseous exchange
 Transparent layer

18. SPECIALISED PARENCHYMA CELLS
 Endodermis
 Selective barrier Between outer cortex and inner
pericycle
 Forming Casparian strip in the roots to prevent
apoplastic movement of water (suberin)
 Pericycle
 Secondary growth of roots
 Aerenchyma
 Oxygen reserve
 Buoyancy for Hydrophytes

19. Endodermis Epidermis

20. SUPPORTING TISSUES
Collenchyma Sclerenchyma
 Living cells  More specialised
 Unevenly thickened cell  Die after maturity
walls with
Cellulose, Hemicellulose  Lignified secondary cell
and Pectin walls
 Extra mechanical  Uniform thickening
strength
 Stretching & elongation  Hard + impermeable to
 Elastic & Flexible water, solute and
 Allow growth of young gases
plants / leaves

21. COLLENCHYMA – LIVING CELLS AT MATURITY

22. SCLERENCHYMA CELLS – DIE AT MATURITY

23. TYPES OF SCLERENCHYMA CELLS

24. TYPES OF
SCLERENCHYMA
 Fibers – are long thin
and fibrous like and
usually occur in bundles
 commercially used to
make rope and flax fibers
 Found together with
xylem
 Sclereids – short and
irregular in shape.
 make up tough seed
coats and pits
 give pears its gritty texture

26. COMPLEX TISSUE – XYLEM & PHLOEM

28. XYLEM
 Transport water and minerals
 Types of Cells
 Tracheids
 Vessel elements
 Xylem fibres (sclerenchyma)
Die on maturity
 Xylem parenchyma Cytoplasm disintegrate
Empty cavity
Lignified – Do not collapse
Have pits – Allow lateral movement
of water

29. XYLEM
Tracheids Vessel elements
 Longer  Shorter
 Smaller diameter  Larger diameter
 Tapered at 2 ends to  Joined end to end
increase strength  Hollow tube
 Have pits in between  No pits in between
 More resistance  Have pits side-by-side with
tracheids
 Lignified
 Less resistance for water
 No perforated open ends  Strengtened with lignin
between cells
 Absent in fern and conifers
 Not hollow tube

30. PITS

31. TRACHEIDS

32. VESSEL ELEMENTS  Spiral / Annular thickening
 High rate of elongation
 Present in young plants to allow
stretching during elongation
 Present in proxylem
 Scalariform / Reticulate /
Pitted thickening
 Low rate of thickening
 Cannot be stretched
 More lignifications
 High tensile strength
 Do not collapse when water flow
through in high tension
 Have pits for lateral movements
of water

33. SECONDARY XYLEM
 Formed in both tracheids and vessel elements
 Except pit regions

34. XYLEM FIBRES & PARENCHYMA
Xylem fibers – similar to
sclerenchyma fibers
Dead and lignified
Only for support
Parenchyma – Living cells
As intermedularry rays for radial
transport of food, water, gases
and storage

35. PHLOEM
 Translocation of organic substances
 Four types of cells
 Sieve tube cells
 Companion cells
 Phloem parenchyma
 Pholem fibres

38. SIEVE TUBE CELLS & SIEVE PLATES
Sieve Tube Sieve Tube Elements
 Elongated  Mature sieve tube
 Living cells  Nucleus disintegrates
 Connected end-to-end
 Cytoplasm remains
 Continuous
cytoplasmic strands
 Sieve plates –
perforated cell wall with
sieve pores

39. CONTINUOUS CYTOPLASM
Sieve tube elements
Alive with thin cell wall and
protoplasm
Upon maturity, nucleus,
ribosome and Golgi
apparatus disintegrates
Only have mitochondria and
ER left for periphery transport

40. COMPANION CELL
 Only found in angiosperms
 Parenchyma cell
 Elongated
 Thin primary wall
 Metabolically active
 Dense cytoplasm
 Large nucleus
 Mitocondria
 Plastids
 Vacuoles
 RER
 Linked to sieve tube
elements by Plasmodesmata

42. PHLOEM PARENCHYMA & FIBRES
 Parenchyma
 Food storage
 Form radial
medullary rays
in phloem
 Fibres
 Support