Biological arguments against a universal flood are answered through a comprehensive study of the relevant Biblical and scientific evidence. Biblical evidence bearing on the following points is studied: Animal groups represented on the Ark, animals classed as clean, number of animals taken from each clean kind, and the gathering of the animals to the Ark. This is supplemented by a biological study of the number of kinds, the relative diversity of clean and unclean animals, and the problem of hibernation. It is concluded that biological arguments against a universal flood are invalid, and that the number of animals under Noah's care probably did not exceed 2,000.