What life forms existed first on Earth?

Whenever ammonia donates an electron pair to form a covalent bond it acts as an? What is Harbin altitude? Is wood an organic matter? What step in glycolysis consists of a phosphorylation reaction in which ATP is the phosphate source? Is it true that earthquake zones coincide with the edges of lithospheric plates? Who uses a seismograph? What On the topographic map contour lines that are close together indicate a? What is the formula mass for the ammonium ion? Why does exposure to carbon dioxide increase the rate of breathing? How do scientists classify intrusive igneous features? Did you know that marble forms from metamorphosed carbonate rock most usually limestone? What type of precipitation occurs at 25 degrees celsius? What is the 5 category of a hurricane? What kind of rock will be found 10 kilometers beneath the Earth's surface? What is the best thermometer for taking temperatures? How do people deal with it when a volcano eruots? How can you make iron II sulfate? How long does the process of erosion take? Sediment that has grains of approximately the same size is said to be? Is sand bigger than clay?

What life forms existed first on Earth?