Kerry Elsdon, age 11, of Medicine Hat, Alta., Canada, for her question:

HOW CAN A MEXICAN BEAN JUMP?

Naturally, no bean can go hopping around without some assistance. In this case, the help is right there inside the Mexican bean. It is a grubby little caterpillar, who sometimes takes a little exercise, especially when things get rather warm. The story starts when a certain drab little moth flies around, searching for just the right spot to lay her eggs. She finds it in a desert shrub  and lays each egg inside one of its small blossoms.

Later the petals fall and the blossom develops a bean ¬type seed  with the moth egg inside. The egg hatches into a hungry grub. The growing bean is a pantry of its favorite food  and as it feeds it hollows out a small room for itself. Now and then, the grub inside coils its body and lets go with a sudden jerk. This is how come the Mexican bean is able to jump around.