AP BIOLOGY

Detailed explanation-1: -Companion cells have a nucleus, are packed with dense cytoplasm contain many ribosomes and many mitochondria.

Detailed explanation-2: -Among other adaptations, companion cells therefore contain many mitochondria. This allows them to carry out cellular respiration at a high rate and, hence, release lots of energy.

Detailed explanation-3: -Companion cells showed a dense cytoplasm and various small vacuoles. They also revealed their characteristic large nucleus and abundant mitochondria.

Detailed explanation-4: -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-5: -This active transport of sugar into the companion cells occurs via a proton-sucrose symporter; the companion cells use an ATP-powered proton pump to create an electrochemical gradient outside of the cell.