Fossils of the first animals are rare because theyA. were large and likely to be eaten by others after they died.


B. lived only in volcanic regions, and were destroyed by lava flows.


C. were soft-bodied and tiny, therefore unlikely to fossilize.


D. had hard shells that broke down easily, leaving no trace

Testosterone is an example of a chemical signal that affects the very cells that synthesize it, the neighboring cells in the testis, along with distant cells outside the gonads. thus, testosterone is an example of ________. i. an autocrine signal ii. a paracrine signal iii. an endocrine signal

During _______, energy from the Sun is stored in the bonds of sugar molecules.

which of the following species demonstrates a matriarchal structure? a.) Chinook salmon, b.) gannets, c.) orcas, d.) sea turtles

Which of the following terms is the accumulation of persistent toxins in our body? carcinogen body burden a biotic factor persistent organic pollutants (pops)?

What do we call plants that have been transformed with foreign dna?

Smallpox is a virus that causes a rash that then turns into painful blisters. The last known case of smallpox was in 1977. What is the best explanation for the eradication of smallpox?