Um help me please:) Thanks

What could happen if two base pairs on a strand of dna or switched

Which one is an advantage of external fertilization a. the offspring are genetically identical to the parents b. more eggs can be fertilzed at one time c. more sperm can be released at one time d. more protection is available for developing plz

Select the word from the list that best fits the definition apparent movement of a star used to measure its distance from earth