Paleontologists organize fossils of related species based on their __________________ similarities.

Phylogenetic trees can always be regarded as ________ about evolutionary relationships.

Organisms that possess homologous structures probably __________.

The critical period for major anomalies is longest for the _____ system.

The bird says____

In cladistics, _______________ is(are) the primary criterion used to classify organisms.

Population density is calculated by _______.

Plasma cells ________.

Parts of the ____ are important for learning about rewards and punishments.

Part a in the diagram below, the gray unit represents _____.

Our brain enables us to do all the following except __________.