K.C.S.E Biology Q & A - MODEL 2016PP2QN05

K.C.S.E Biology Q & A - MODEL 2016PP2QN05

A freshly obtained dandelion stem measuring 5cm long was split lengthwise to obtain two similar pieces. The pieces were placed in two different solutions of different concentrations in petri dishes (L1 and L2) for 20 minutes. The appearance after 20 minutes is as shown.

​(a) Account for the appearance of the pieces in solutions L1 and L2 
(b) Suite the significance of the biological process involved in the experiment.

answers

(a) L1 - Inner cells gained water by Osmosis; hence increased in length; epidermal cells did not gain water because they are covered by a water proof cuticle leading to curvature.
 L2 - Inner cells lost water by osmosis; leading to (flaccidity) decrease in length; epidermal cells did not lose water due to waterproof leading to curvature
(b) Absorption of water by the roots
 Opening and closing of the stomata