NDA Biology · Free notes
Genetics and Evolution — NDA Biology
Genetics and Evolution is a small chapter in NDA Biology — only a handful of PYQs across 2017–2026, all EASY or MODERATE, and all pure named-fact recall. Because the bank is thin, this chapter is built foundation-first: it teaches the whole topic from zero — what a gene is, how DNA is structured, how traits are inherited, and how species change over time — so a student (or a teacher using it as a lesson plan) gets the complete picture, not just the four questions that happen to have been asked. The chapter teaches in two movements: (1) Heredity and DNA — the gene as the unit of inheritance, the double-helix structure of DNA with its A–T and G–C base pairing, alleles and genotypes, Mendel's laws, and the scientists who cracked the structure; (2) Evolution — what evolution means and Darwin's theory of natural selection. Learn the base-pairing rule, the allele definition, the Watson–Crick–Wilkins story, and Darwin cold, and every PYQ in this chapter is free.
The handout has every subtopic, worked example, formula and trap with answers shown. The formula sheet is the chapter’s formulas and traps alone, on one page.
Subtopic notes
Heredity, DNA and Genes
3 PYQsHeredity is the passing of traits from parents to offspring through genes — segments of DNA, the double-helix molecule whose A–T and G–C base pairing carries all genetic information.
The Theory of Evolution
1 PYQsEvolution is the gradual change in the heritable characteristics of a population over many generations; Darwin explained it through natural selection — the survival and reproduction of the best-adapted individuals.
Formula & revision sheet
1 formulas · 1 reference tables · 7 gotchas across all subtopics — the exam-eve cheat-sheet
Formula & revision sheet
1 formulas · 1 reference tables · 7 gotchas across all subtopics — the exam-eve cheat-sheet
Reference tables (1)
Who discovered the structure of DNA4 rows
| Scientist | Contribution |
|---|---|
| James Watson & Francis Crick | Built the double-helix model of DNA (1953) |
| Maurice Wilkins | X-ray diffraction studies of DNA; shared the 1962 Nobel Prize Wilkins is the name the 1962-Nobel question asks for — alongside Watson and Crick. |
| Rosalind Franklin | X-ray photograph ('Photo 51') that revealed the helix; died 1958, so not in the 1962 prize |
| Erwin Chargaff | Chargaff's rules — in DNA, A = T and G = C |
Watch out for (5)
- A pairs with T, not with G or C→ DNA structure and base pairing
- G–C has 3 hydrogen bonds, A–T has 2→ DNA structure and base pairing
- Allele vs genotype vs isomer→ Genes, alleles and genotype
- 3 : 1 is the phenotype ratio, 1 : 2 : 1 is the genotype ratio→ Mendel's laws of inheritance
- Franklin and Chargaff are the distractors in the 1962-Nobel question→ Who discovered the structure of DNA
Watch out for (2)
- Darwin wrote 'The Origin of Species' — not Linnaeus or Lamarck→ Darwin and natural selection
- Darwin vs Lamarck→ Darwin and natural selection
PYQ weightage by concept
7 concepts · 4 PYQs — where the marks actually sit, so you know what to drill first
PYQ weightage by concept
7 concepts · 4 PYQs — where the marks actually sit, so you know what to drill first
| Concept | PYQs | Share |
|---|---|---|
| DNA structure and base pairing | 1 | 25% |
| Genes, alleles and genotype | 1 | 25% |
| Who discovered the structure of DNA | 1 | 25% |
| Heredity — genes, chromosomes and DNAfoundation | — | — |
| Mendel's laws of inheritancefoundation | — | — |
| Concept | PYQs | Share |
|---|---|---|
| Darwin and natural selection | 1 | 25% |
| What evolution meansfoundation | — | — |
Test yourself on a real paper
Sit a past NDA paper, timed and marked the way the exam marks it. You see your score and every answer the moment you finish. Free to start.