According to the Precambrian rock record, much of Earth's first free oxygen combined with

Ecosystem encompassing all the life on earth in the physical environment that supports it

According to the endosymbiotic theory, some organelles found in modern eukaryotic cells may be the result of a symbiotic relationship between ancient prokaryotes.

The wall of the alveolus is composed of which type of epithelium

Which of the following is the best definition of DNA? A. A molecule made up of a long string of amino acids B. A double-stranded molecule with coded instructions for an organism's physical characteristics C.

What is always conserved in a chemical reaction? Mass is always conserved in a reaction. Energy is always conserved in a reaction. Mass and energy are both conserved. Nothing is always conserved in a reaction.

Chemical reactions in cells are faster than the same reactions outside cells. True False

What are WBCs and what do they create to fight off infections?

Which term names the replacement of living cells with minerals to form a rock-like fossil of a living thing? A. mold fossil B. petrified fossil C. cast fossil D. trace fossil

What is the diffrence between working in a field or laboratory

What does the principle of descent with modification imply?