One scientific hypothesis about the origin of life holds that
a.
rna replaced dna as the most stable information-storing molecule.
b.
rna nucleotides were formed from simple organic molecules in an abiotic stew.
c.
proteins that duplicate themselves came to function in information storage.
d.
as cells evolved, rna came to direct protein synthesis.
e.
as cells evolved dna replaced rna.

Which organ controls breathing? lungs alveoli heart diaphragm

Fossils of ancestors of the modern horses show a small 4-toed almost dog-like browsing animal named eohippus over time the horses got larger lost toes and changed to a grazing diet what is the best explanation of why this change occurred

The images show two species of tree frogs in a particular region. the gray tree frogs are adapted to the trees of the woodlands, while the green tree frogs can survive in woodlands or grasslands. the gray frog was abundant in the woodlands. because of climatic changes, most of the trees in the region died, and the woodlands changed to grasslands. in such a case, the . the gray tree frog is closely related to the green tree frog genetically, but they have different mating calls. this suggests that speciation occurred because of .