Help please i need to pass this grade

In dna, only the_ varies from one nucleotide to another. base phosphate sugar amino acid

The body is protected against harmful flu viruses by

Amale bird-of-paradise uses a dance to attract mates in which it flaps its tail feathers on the ground and jumps around a potential female mate. a different male bird-of-paradise does a similar dance but it jumps around the female in the opposite direction. the female bird is only attracted to one style of dance, in one direction. this is an example of speciation.