External fertilization occurs mostly in

a.) aquatic animals
b.) insects
c.) animals that reproduce asexually
d.) land animals
e.) mammals

The terrestrial planets are characterized by having a a.) silicate core b.) iron-rich silicate core c.) iron-rich metallic core d.) none of these

1. in what ways have non-native species been beneficial? 2. what are some of the hypotheses for the collapse of honeybee colonies? 3. distinguish between regional and functional extinction. 4. why is it difficult to measure background extinction rates? 5. what three factors are most important in causing extinction rates to climb?

Which hypothesis most likely explains the results at 60°c and 70°c