“Observe and describe developmental patterns in selected plants and animals.”

Once the egg becomes fertilized changes begin immediately. These changes are complex in nature and are very important to the survival of the organism. The fertilized egg undergoes many cellular divisions. The image below shows how the egg cell divides. These dividing cells become specialized to perform a specific function. These specialized cells become tissues. Tissues working together form organs. In humans this all develops before birth. As an organism develops and grows it can go though a variety of changes in its structure. For example, a frog starts its life as a tadpole. The tadpole spends most of its time underwater. As the tadpole develops into an adult frog its body shape changes. This all happens during the course of its life cycle.