Which one of the following agents does not contribute to propagation of plants through seed dispersal?

The correct answer is B, Fungus. Seeds are carried away from the parent plant by wind, water and animals, but fungi play no part in seed dispersal.

Plants spread their seeds so that the young plants do not crowd the parent and compete for light, water and nutrients. Seeds dispersed by wind are light or have wings and hairs, as in drumstick, maple, cotton and the dandelion. Seeds dispersed by water, such as the coconut and lotus, have spongy or fibrous coats that let them float. Animals spread seeds by eating fleshy fruits and passing the seeds out, or by carrying hooked fruits like Xanthium on their fur. Some plants, such as the balsam and castor, burst open and throw their seeds out themselves.

A is wrong because wind is a major agent, especially for light and winged seeds. C is wrong because animals, including birds and people, carry seeds far and wide. D is wrong because water carries floating seeds such as the coconut across rivers and seas.

Exam tip: wind, water, animals and explosion are the four ways seeds are dispersed.