The genotype will be BBCC as since it can only have brown offspring it has to be a purebred, Purebreds are homozygous.
Answer:
You may have heard that your heart skips a beat when you sneeze, but that's a myth. Electrical signals that control your heart rate aren't affected by the physiological changes that happen when you sneeze. But the heart may get delayed for a second or two before resuming its regular rhythm.
Short answer - to breathe.
Long answer - the black streaks on the trunk of birch trees are called lenticels, and their function is to enable the exchange of gases between the tree and the air. So, in a way, this makes the whole process of photosynthesis a lot easier for birch trees.
