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 anaerobic and aerobic respiration use glucose (or other carbohydrates), proteins and lipids to produce atp and nadh. cell uses those energy molecules, obtained from food and   breaks them down during the chemical reactions of respiration. in anaerobic respiration, nadh is regenerated to nad+ by enzymes lactate dehydrogenase (lactate is produced, e.g. in muscle cells) or by alcohol dehydrogenase where ethanol is produced (alcohol fermentation), while in aerobic respiration, electrons from nadh are deposited in the mitochondria to regenerate nad+ (electron transport chain. anaerobic respiration produces 2 atp per molecule of glucose compared to aerobic respiration where about 38 atp molecules are produced.

a physical change is being made.