When a baby was five months old she weighed 8 kg after seven years the baby has grown into a girl weighing 25 kg where did her increase in mass come from

The girls mass would have increased as she is growing and the bones in her body are growing and becoming stronger. Her weight would also change drastically as she’s getting older. Peak bone mass is influenced by a variety of factors: some that you can't change, like gender and race, and some that you can, like nutrition and physical activity. Calcium is an essential nutrient for bone health. A well-balanced diet including adequate amounts of vitamins and minerals such as magnesium, zinc, and vitamin D is also important.

you know they are heterozygous for a trait because they have it as jj or jj.