K.C.S.E Biology Q & A - MODEL 2012PP2QN04
The diagram below illustrates arrangement of bones and muscles of the human arm.
(i) Name the bones labelled K and L.
(ii) Explain how the upward movement of the lower arm is brought about by the, bones and muscles shown in the diagram above.
(b) State three ways in which support is brought about in a leaf.
(a) (i) K - ulna;
L - humerus;
(ii) movement of the lower arm upwards takes place at the elbow/olecranon process which is between the ulna and the humerus; biceps/flexor muscles contract; while the triceps/extensor muscles relax; bringing about the movement of the lower arm upwards. ,
(b) The rigid midrib holds leaf out away from the stem;
Profuse network of veins have lignified cells which support leaf to stay spread out;
Turgidity in spongy mesophyll and palisade cells support the leaf to remain open;