If photosynthesis and cellular respiration form a cycle, why do plants need to continually take in carbon dioxide, oxygen, and water from the environment?

One of the hopes for solving the world's energy problem is to make use of the fusion reaction 21h +31h --> 42he + 10n + energy how much energy is released when 1 mol of deuterium is fused with 1 mol of tritium according to the above reaction? the masses of the atoms and the neutrons are as follows: 21h = 2.0140 amu 31h = 3.01605 amu 42he = 4.002603 amu 10n = 1.008665 amu. the speed of light is 2.9979 x 108 m/s.

Consider the story you just read. all but one of the choices below indicate that something is living.

If one fission reaction of a uranium-235 atom produced two neutrons, how many neutrons would be released if the chain reaction occurred three more times?