Polygalacturonoids (pectins) are the major constituents of:

Assertion $A$: The middle lamella is present between the primary walls of two adjacent plant cells.
Reason $R$: Two adjacent cells maintain cytoplasmic contact through plasmodesmata.
Which option is correct for Assertion $A$ and Reason $R$?

Which one of the following is present outside the plasma membrane but inside the cell wall?

How many micelles combine to form a microfibril?

In which of the following are the cells held together by a $Ca$-pectate layer?

Which one part of the cell is non-living?