Two characteristics used to define mammals include
a. mammary glands and scales.
b. mammary glands and hair or fur.
c. mammary glands and sweat glands.
d. sweat glands and a four-chamber heart.

Which of the following is not a possible effectof increasimg carbon dioxide levels in the atmosphere ?

According to theories of how life began, how did early organic molecules begin to separate from the outside world? a: specialized enzymes were required b: chains of amino acids created a barrier c: formation of microspheres or vesicles d: rna catalyzed the formation of membranes

The wind is to parities grasses because it them