Question

The gritty texture to the pulp of fruits like guava and pyrus is provided by
(A) Osteosclereids
(B) Macrosclereids
(C) Astrosclereids
(D) Brachysclereids

Answer 1

Hint: Sclerenchyma is made up of two main components – fibres and sclereids. Sclereids are specialized sclerenchyma cells that occur in a variety of shapes. Sclereids have very thick and lignified walls. Mature sclereids are dead lacking any live content.

Complete answer:
Sclereids are of following types:
> Osteosclereids: Osteosclereids have thick ends that make them appear like bones or hourglass. Hence, they are also known as bone cells or hourglass cells. Osteosclereids are made up of columnar cells. They are present in tissues like soft pea seed coats.
> Macrosclereids: Macrosclereids are similar to osteosclereids but they are elongated in shape lacking thick ends. They are also made up of columnar cells. They are present in hard seed coats of legume plants where they restrict the uptake of water. Macrosclereids are also known as malpighian cells.
> Astrosclereids: Astrosclereids are branched, pointed, irregular star shaped sclereids that are uncommon in occurrence. They can be seen in leaves of water lily which float on water.
> Brachysclereids: Brachysclereids are similar to parenchyma cells in shape. They are also known as stone cells due to the presence of hard walls. They are present in parts of stems like pith, bark and cortex and also in some fruits like guava and pyrus. These cells are also called grit cells as they impart grittiness to the pulp of fruits like guava and pyrus.
> Trichosclereids: Trichosclereid are also uncommon. They are long and hair like or fibre like in appearance. They are present in leaves of olive. They can also be found in aerial roots of plants called Swiss cheese.

So the correct answer is Option (D) Brachysclereids.

Note:
Sclereids are found in different plant tissues or parts like vascular tissues (xylem and phloem), periderm, cortex, pith, bark, leaves, and fruits. Sclereids perform different functions. They provide internal support to the organ, prevent desiccation of hard seeds, and prevent herbivorous animals from eating leaves of certain plants.