What is the most common energy source for cells?

Compare and contrast nutrient limitation in soil vs. nutrient limitation in aquatic ecosystems

What do isotopes of uranium have the same number of? what do they have a different number of? a) same number of protons; different number of electrons b) same number of protons; different number of neutrons c) same number of electrons; different number of protons d) same number of neutrons; different number of protons

What type of plant is good for a bioassay and where can i buy it? i only have a month.