The big picture
Here is the whole track in one table.
| Lesson | The rule |
|---|---|
| Resemble both, match neither | Each trait has two gene copies, one from each parent. One copy can hide the other. A child may match one parent in shape. It may match the other in colour. |
| The man who counted | Mendel used true-breeding lines, crossed them by hand, and counted every offspring. Counts turn a guess into a pattern you can test. |
| The hidden one comes back | A gene pair has two copies. A dominant copy shows in the plant. A recessive copy shows only when both copies are recessive. |
| The count is the argument | Two Tt plants are crossed. Each seed gets T or t from each parent. So the four pairs TT, Tt, Tt and tt are equally likely. Three of them give tall plants. One gives a short plant. |
| Two traits at once | Two gene pairs are passed on separately. That gives sixteen equally likely boxes. In big counts, the looks come near nine, three, three and one. |
| Which contribution decides | A parent with a mixed pair can pass either kind. A parent with a matching pair always passes the same kind. In people, the father has the mixed pair, XY. So the father's sperm decides the sex. |
| The laws in plain words | Dominance: one form of a gene can hide another. Segregation: a pair separates, and each parent passes one gene. Independent assortment: two gene pairs sort into gametes independently. |
Now open your Class 10 Science book at Chapter 8, Heredity. You have counted its ratios yourself.