Out of xylem and phloem, which one carries materials : (a) upwards as well as downwards ? (b) only upwards ?
What substance/substances are transported in plants by : (a) xylem vessels and tracheids ? (b) sieve tubes (or phloem) ?
Which one of the following has cytoplasm but no nucleus : (a) xylem vessel (b) sieve tube (c) tracheid (d) companion cell