Biology
High School (11–12)
Heredity and Evolution › Principles of Inheritance and VariationChapter 22Contains Standard contentPrinciples of Inheritance and Variation
Why do you look like your parents, and yet not exactly like either of them? This chapter follows a trait from parent to child. You start with Mendel and his peas and learn to predict the results of a cross. Then you meet the chromosomes that carry the genes, linkage, sex determination and the traits tied to the X chromosome. You end with mutations and the genetic disorders that follow from them. Python counts every cross exactly, with fractions, so that no ratio is guessed. It serves the Indian syllabus (NCERT, NEET) and the matching topic of A-Level, IB and AP. A fourth course goes deeper, for readers who want the level of A-Level Biology, IB Higher Level and the Olympiad.
Part of Biology · High School (11–12) (chapter 22)
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Mendel's Laws and Their Extensions
Two pea plants cross, and the children look like only one of them. Where did the other trait go? You follow Mendel's crosses with one gene and then with two, and you learn to predict the ratios. Then you meet the cases that Mendel did not see: incomplete dominance, codominance, the blood groups, pleiotropy and traits made by many genes. It serves the Indian syllabus (NCERT, NEET) and the matching topic of A-Level, IB and AP.
Chromosomes, Linkage and Sex
Mendel never saw a chromosome. Later workers found that genes sit on chromosomes, and that explains both his laws and the places where they fail. You see how linked genes travel together, how crossing over breaks the link, and how a map is made from the counts. Then you follow the ways in which sex is decided, and the traits tied to the X chromosome, such as haemophilia and colour blindness. It serves the Indian syllabus (NCERT, NEET) and the matching topic of A-Level, IB and AP.