OBJECTIVE FORESTRY

Detailed explanation-1: -The companion cells have dense protoplasts which contain the typical organelles of plant cells, including chloroplasts and many ribosomes. The sieve elements and companion cells are interconnected by numerous branched plasmodesmata. The companion cells degenerate when the associated sieve elements cease to function.

Detailed explanation-2: -The companion cells are specialized parenchyma cells in the phloem tissues of the angiosperms. They are nucleated living cells with several ribosomes, plastids, and mitochondria. Their nuclei and nucleoli are relatively large (an indication of being metabolically active).

Detailed explanation-3: -Companion cells are found along with sieve tube elements in the phloem tissue.

Detailed explanation-4: -The phloem is composed of three types of cells – the conducting cells, the parenchyma cells and the supportive cells. The conducting cells, also called sieve elements, are composed of columns of sieve tube cells that have perforations in their lateral walls and that helps in the conduction of food throughout the plant.