Astronomer Edwin Hubble classified galaxies<span> into four major types: spiral, barred spiral, elliptical and irregular. Most of the nearby, bright </span>galaxies<span> are spirals, barred spirals or ellipticals. Spiral </span>galaxies<span> have a bulge at the center and a flattened disk containing spiral arms.</span>
A Only one variable changed
Answer:
fish and tetrapods are both vertebrates that have a backbone with a spinal cord. fish lived before tetrapods because their fossils are in rocks over 500 million years old.
Explanation:
fish and tetrapods are both vertebrates that have a backbone with a spinal cord
Anaerobic respiration<span> in muscles. Glucose is not completely broken down, so much less energy is released than during </span>aerobic respiration<span>. There is a build-up of lactic acid in the muscles during vigorous exercise. The lactic acid needs to be oxidised to carbon dioxide and water later. Hope this helps!</span>
