K.C.S.E Biology Q & A - MODEL 2015PP2QN07
Explain the various ways in which seeds and fruits are adapted to dispersal.
Wind - dispersed seeds / fruits are light / small to be carried by air currents;
Some seeds / fruits have developed hairy structure feather-like projections; wing like structure which increase their surface area to be blown about /carried away by wind; open capsules; borne on long stalks, which are swayed by wind scattering seeds.
Water - dispersed fruits / seeds are also light; to float on water;
Some, (like coconuts) have fibrous /spongy mesocarps to trap air; making them buoyant/floating on water; Others (like the water lily) produce seeds whose seed coats trap air bubbles; making them float on water; Some have water-proof seed testa / pericarp; remain afloat without soaking /sinking immediately they are released from parent plants;
Animal - dispersed fruits have developed hooks; to stick on (the fur of passing) animals;
In some cases, fruits are succulent, brightly coloured / scented; to attract animals, birds;
The seed coats (of some seeds) are hard; and resistant to the digestive enzymes; hence passing out through the gut undigested;
Self dispersal by explosive mechanism;
Fruits have sutures/lines of weakness; which split open when drying scattering seeds.