Which of the following is a basic evolutionary advance needed to convert a down-like feather into a primary flight feather. a. The feathers rachis must be lengthened and reshaped to help support the birds weight
b. Down like feathers must become smaller in size
c. Down like feathers must grow out more quickly
d. Preening behavior must be eliminated from bird behavior
e. Adhesive proteins must be formed more quickly

Clara wrote the following hypothesis for an experiment about acidophilic bacteria. bacteria cells will stop dividing in a basic (alkaline) environment because of the high ph. which statement is the best way to restate the hypothesis so that it is more specific? growing acidophilic bacteria in some environments will cause the cells to stop dividing because of ph. if the ph of their environment is changed, acidophilic bacterial cell division will be affected. if the environment of acidophilic bacterial cells becomes alkaline, the bacteria will stop dividing. the more alkaline an environment, the less cell division will occur in bacteria.