Question

‘Druse’ is a crystal or deposit of
A. Calcium oxalate
B. Calcium carbonate
C. Starch
D. Silica

Answer 1

Hint: Plants accumulate druse within a range of 3–80 percent (w/w) of their dry weight via a variety of forms of biomineralization process.

Complete Answer:
- Druses have been found in the leaves and stems of six studied plant species. A druse is a gathering of silicate, or carbonate crystals, found in plants and is believed to be a protection against herbivory owing to its toxicity.
- In addition, more than 215 groups of crystals that are present in algae, angiosperms and gymnosperms.
- Druses may have a role in controlling calcium, too. The precise mechanism regulating this process is unknown but it has been proposed that a variety of factors, such as proteins, polysaccharides, lipids, or macromolecular membrane structures, affect the crystal shape and development.

Now, let us find the solution from the option.
(I) A druse is a group of Calcium oxalate Crystals.
(II) It is found both in plants with angiosperms and gymnosperms, and even in some algae.
(III) Calcium oxalate creates needle-like raphides, prismatic crystals, star-like sphaeraphides or druses or powdery material called crystal sand.
(IV) The toxic compounds in druses provide protection against herbivory.

Thus, the correct option is (A) Calcium oxalate.

Note: A series of biochemical pathways for biomineralization of calcium oxalate have been suggested in plants. Of which include citrate splitting, oxaloacetate hydrolysis, glyoxylate oxidation or L-ascorbic acid oxidation.