Question

Idioblasts are
(a) Sclerenchymatous fibres found in the leaf of Yucca.
(b) Specialised parenchymatous cells which contain organic substances.
(c) Collenchymatous cells possessing angular thickenings.
(d) Crystals of calcium oxalate found in hard fruits.

Answer 1

Hint: Idioblasts are non green cells. They are large in size and store tannins, oils and crystals in parenchymatous cells. Therefore, idioblasts are specialised parenchymatous cells which contain ergastic substances.
Some idioblasts contain mineral crystals such as poisonous calcium oxalate or carbonate or silica.

Complete answer:
Idioblasts are divided into three main categories:
Excretory idioblasts that store oils, lipids, tannins and minerals.
Tracheoid idioblasts resemble tracheids, pr water conducting cells.
Sclerenchymatous idioblasts are thickened structural cells that provide stability and rigidity to the plant.
The uneven division of idioblasts causes extreme differentiation in their daughter cells, with many daughter cells having different functions from their parent cell.

Let us see from the given Choices which is the correct answer:
> Yucca leaf yields a large amount of fibres which are useful for many things but there is no connection between yucca and idioblast so this is not a right option.

> Specialised parenchymatous cells which contain organic substances. This option is correct as idioblasts are the specialised parenchymatous cells which store oils.

> Collenchymatous cells originate from the modification of parenchyma cells comprising thickened walls and this is not called idioblasts. So, this option is not correct according to the question.

> Crystals of calcium oxalate are formed in the vacuoles of idioblasts . Therefore, this option can not be considered right.

Hence, The correct answer is option (B).

Note: Specialised idioblast cells are present in avocado fruit tissue and contain lipid and lipid soluble compounds. Some axial idioblasts produce and store phenolic or resinous metabolites for defence purpose. Idioblast is a plant cell that differs in shape or function from neighbouring cells within the same tissue.