Question

1. Why are some fruits sweet and some sour, whereas others have no specific taste?

Answer 1

It all depends on the chemistry of the fruits, fruits contain different levels of fructose and glucose which will affects their sweetness and contain different levels of acids such as vitamin c/ascorbic acid and citric acid (in lemons and limes) which will determine how sour the fruit is. They contain all sorts of other compounds/vitamins/minerals as well, which will affect how they taste.