1. The common ancestor of all the tetrapod vertebrates had four limbs with a similar skeletal structure to thatseen in many vertebrates today. Considering this, in what sense are the arms of humans homologous to the wings of a bird?

2. The green algal ancestors of plants existed in aquatic habitats, contained chlorophyll a and b, and had cellwalls composed mainly of cellulose. Land plants also contain chlorophyll a and b and have cell walls ofcellulose. What traits in the land plants are primitive? What trait represents divergent evolution from theancestral form?

3. The ancestors of hominids were quadrupeds, walking on four legs. Humans are bipedal. Is this characterderived or ancestral? Are the walking habits of chimpanzees primitive or advanced?