Some organism suspend their metabolic activities to survive in unfavourable conditions.Explain with the help of any four examples

(a) The frogs hibernate very cold season and reduce their metabolic activities.
(b) The kangaroo, rat has the ability to concentrate its urine and can live from birth to death without drinking water, there by conserving water.
┬ęBarnacles and molluscs, living in very cold intertidal zones of northern shores, show their reduce activities.
(d) Some animals go to summer sleep.