What is a single- ringed nitrogenous base

Need an answer asap 45 points and brainlest to the first person to answer why do scientific theories, such as biological and chemical evolution, represent the strongest explanation of the changes observed in the fossil record. must be in sentence form how can scientific theories on evolution and the fossil record change over time? must be in sentence form

What is the correct term for an area of rotating currents in an ocean? when ocean currents combine, they create an area of rotating currents called an

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