Question

Do all cells have a primary cell wall composed of cellulose?

Which cell type (parenchyma, collenchyma or sclerenchyma) have a secondary wall substantially composed of lignin?

Answer 1

Ans. The primary cell wall is a thin , flexible and extensible layer of cell wall composed of cellulose (plants), pectin and hemicellulose ( especially ,xyloglucan ) . The layer of the plant cell wall forms prior to the deposition of second cell wall .

Or animal cell do not contain cell wall.

# sclerenchyma cells are characterized by relatively thick ,lignified secondary cell wall . All plant cells initially have only a primary wall made predominantly of cellulose . As sclerenchyma develops,a secondary wall with a high proportion of lignin is deposited inside the primary wall.