What is one situation in which population density could have a negative impact on the production of offspring

Out of the seven main animal groups (fish, mammals, birds, insects, reptiles, amphibians, and arachnids), how many contain members with internal backbones? a. 5 b. 3 c. 7 d. 1

In iceland, the mid atlantic ridge runs through the center of the contry. what can you conclude about the apperence of iceland many thousands of years from now?

Which kind of worm has a closed circulatory system? a planarian b fluke c pinworm d an earthworm