K.C.S.E Biology Q & A - MODEL 2015PP2QN05

K.C.S.E Biology Q & A - MODEL 2015PP2QN05

In an experiment to investigate a plant response, the set up shown in the diagram below was used.

(a) Name the type of response that was being investigated. 
(b) If the Klinostat was not rotating:
(i) state the observations that would be made on the seedlings after three days; 
(ii) explain the observations in (b) (i) above. 
(c) If the experiment was repeated with the Klinostat rotating:
(i) state the observation that was made on the seedlings after three days; 
(ii) give a reason for the observation made on the seedlings.

ANSWERS

​(a) Geotropism/Gravitropism; 
(b) (i) The shoot tip/plumule curved upwards; root tip/radicle curved downwards; 
(ii) Auxins migrated downwards to lower side; Higher concentration on the lower side; caused more growth on the lower side than on the upper side in shoots inhibited growth on the lower side than on the upper side in the roots; 
(c) (i) The seedling will continue growing horizontally; 
(ii) There was even distribution of auxins (on the tips);