Chapter 6

Assertion: Sieve tube member and companion cells are called sister cells Reason: Both derived from same mother cells and death of one results in death of other as well.

Assertion: Function of sieve tubes is controlled by nucleus of companion cells. Reason: Companion cells help in maintaining the pressure gradient in sieve tubes.

Assertion: Cuticle prevent loss of water from epidermis Reason: Cuticle is made up of waxy thick layer and cover epidermis

Assertion: Vascular bundle of dicot stem said to be open Reason: Such vascular bundle contain cambium which possess ability to form secondary xylem and phloem tissue

Assertion: In dicot stem endodermis is referred as starch sheath Reason: Cells of endodermis are rich in starch grains.

Assertion: Bulliform cells in grasses use to minimise water loss under water stem condition. Reason: They are flaccid due to water stress and make the leaf curl inside thus minimise surface area for transpiration.