The companion cells are specialized ........ which are closely associated with sieve tube elements.

Damaged sieve tubes are sealed by the deposition of:

Given below are two statements:
Statement $I$: Parenchyma is living but collenchyma is dead tissue.
Statement $II$: Gymnosperms lack xylem vessels but presence of xylem vessels is the characteristic of angiosperms.
In the light of the above statements,choose the correct answer from the options given below:

Assertion: In angiosperms,the conduction of water is more efficient because their xylem has vessels.
Reason: Conduction of water by vessel elements is an active process with energy supplied by xylem parenchyma rich in mitochondria.

Distinguish between: Parenchyma and Sclerenchyma.

Plant cells without the nucleus are