In the model of dna, if the yellow peg represents cytosine, then the green peg must be a) adenine. b) guanine. c) thymine. d) uracil.

I suppose the yellow peg is facing the green peg, in which case the green peg must be guanine.

The bases are associated in pairs. In each pair there is always a purine associated with a pyrimidine. The association is by weak bonds: the hydrogen bonds, two bonds for an AT pair; three links for a GC pair. When we know the sequence of one strand we can deduce the sequence of the other strand. The two strands are oriented opposite to the 3 'and 5' ends (the strands are called antiparallel).

For Future users the answer is B.  Remember A=T  and C=G hope that helps if anyone needs it!

both male and female gametes are produced by meiosis of the germ cells. therefore, both male and female gametes are haploid. one male and one female gamete unite during the fertilization to form the diploid zygote. in seed bearing plants, pollen grain is the male gametophyte, which produces sperm cells.