Question

Differentiate between the following:

1. Sieve cells and Sieve tubes 

2. Sclereids and fibres 

3. Tracheids and vessels 

4. Sclerenchyma and parenchyma

Answer 1

 

1.

Sieve cells	Sieve tubes
Sieve cells have no companion cells	Sieve tubes always have companion cells
Sieve areas do not form sieve plates	Sieve areas are confined to Sieve plates
Cells are elongated and are unique long with tapering end walls	Cells consist of vertical cells placed one above the other forming long tubes connected at the walls by sieve pores
Sieve pores are smaller and numerous	Sieve pores are larger and fewer in number
Sieve cells are found in pteridophytes and gymnosperms	Sieve tubes are found in angiosperms

2.

Sclereids	Fibre
Usually broad	Elongated narrow thread like
End walls blunt	End walls tapering
Occur singly	Occur in bundles
Deep pit	Narrow pits

3.

Tracheids	Vessels
Formed from single cells	Made up of number of cells
Ends are oblique and taper	Ends are round and transverse
Fraction of a cm in length	Several cms in length
Walls are thick,lumen-narrow	Walls are less thick,lumen- wide

4

Sclerenchyma	Parenchyma
Cells are thick walled and lignified.	Cells are thin-walled and unspecialised.
Tissues are made up of dead cell	These are living cells.
No intercellular spaces between the cells are found.	Cells are usually loosely packed with large intercellular space.
Provides strength to the plant parts.	Stores nutrients and water in stem and roots.
The cells are long and narrow, making the plant hard and stiff. The tissue is present in the stem around vascular bundles in the veins of leaves and the hard covering of seeds and nuts.	Some cells contain chlorophyll called chlorechyma and perform photosynthesis. Other cells have larger air cavities called arenchyma which provide buoyancy to the hydrophytic plants.