The increase in atmospheric carbon dioxide 3.5 billion years ago would have likely been contributed to by
A. early cells beginning the process of photosynthesis and producing sugars.
B. early cells using hydrogen sulfide in the formation of biomolecules.
C. increasing colonies of cyanobacteria undergoing photosynthesis.
D. early cells undergoing anaerobic lactic acid fermentation.

Why is earth's outer core hotter than earth’s oceanic crust? earth’s oceanic crust is denser than earth’s outer core is. earth’s oceanic crust has lava flowing from the mantle. earth’s outer core has a composition of solid iron and nickel. earth’s outer core is deeper within earth than oceanic crust is.

Some substances but not other can cross the (blank) membrane of a cell

Monarch butterflies have brightly colored orange wings with black patterns on them, making them easily visible to birds that eat butterflies and moths, yet birds rarely eat the monarchs. likewise, the monarch caterpillars are brightly striped yellow and white and black, and they also are rarely eaten by birds, although some wasps will attack them and feed them to their young. what can be inferred from these observations? monarchs must threaten and attack birds, but not wasps. monarchs have a way of discouraging bird predation that does not involve hiding. monarchs’ wings are so colorful that most birds must find them difficult to eat. monarchs lay more eggs than other less conspicuous butterflies.