Which action characterized Earth's earliest atmosphere (atmosphere I) ? Helium and hydrogen gases escaped earth's gravity.
Increased oxygen allowed reptiles to thrive.
Heat energy was retained and water vapor condensed.
Ultraviolet light split water vapor into hydrogen and oxygen.

Several bird species feed in a certain species of tree. each bird species feeds in a different part of the tree. which statement is true of these bird species? a. they have adapted to different niches due to competition b. they have a carnivorous relationship with the tree species. c. they have adapted to different niches due to predation d. they have a symbiotic relationship with the tree species.

Apuppy’s tendency to chew is inherited through which of the following? a. through learned behavior b. through genes c. through seasonal cycles d. through hibernation

Which of the following statements about protists are true? a. they are typically found in moist environments. b. they are all unicellular. c. they have a nucleus. d. they are all multicellular.