All changes in heat, or energy, can be explained. Many of the reactions or changes we see in the world involve the conversion of energy. For example as we heat up a substance (eg. water), the amount of energy we put in should give us an exact temperature. However, this is a "perfect world" scenario, and does not occur in real life. Whenever heat is added to a substance like water, we always need to account for the energy that is going to be lost. For example, heat lost to evaporation or even the effect of measuring the temperature with a thermometer (the introduction of anything including a thermometer will affect the temperature).
The height of the plant is controlled by two alleles - the dominant 'T' for tallness and recessive 't' for shortness of the plant. The dominant allele represses the expression of the recessive allele. The recessive allele is expressed only in the homozygous state (tt)