The force of gravity makes things fall to earth.

地心使物体落向地面。

The geotropism growth was a response of hypha to gravity and the geotropic sensitive was at the hyphal apex.

丛枝菌根真菌菌丝延伸长部位是菌丝尖，长向地是对地心感应，感应敏感部位也在长菌丝尖。