Pearson Edexcel International GCSE in Biology · 4BI1 · Free · no account needed
Topic 3 · Reproduction and inheritance
How new organisms are made and how characteristics travel between generations — flowers, the menstrual cycle, DNA, genetic diagrams, mitosis and meiosis, mutation and natural selection.
Every lesson here ends the same way: learn it, teach it to an AI pupil who asks the awkward question, then defend it against the thinker with the strongest claim on it — free · no account needed.
15 lessons, covering 39 specification statements.
What you need to know — the 39 statements, and where each one is taught
Every statement this topic carries, in the specification's own numbering, with Incandio's restatement of what it asks and the lesson that discharges it. Tick them off against your own copy of the specification: this is the topic's revision checklist, not a summary of it. Incandio is aligned to this specification. It is not published by, endorsed by or affiliated with Pearson, and it reproduces none of Pearson's wording — the statement numbers are given so you can check every lesson against your own copy.
| Statement | What it asks | Taught in |
|---|---|---|
| 3.1 | Differences between sexual and asexual reproduction | Sexual and Asexual Reproduction |
| 3.2 | Fertilisation as the fusion of gametes to produce a zygote that develops into an embryo | Sexual and Asexual Reproduction |
| 3.7 | Asexual reproduction in plants by natural methods (runners) and artificial methods (cuttings) | Sexual and Asexual Reproduction |
| 3.3 | The structures of insect-pollinated and wind-pollinated flowers and their adaptations | Flowers, Pollination and Fertilisation |
| 3.4 | Pollen tube growth and fertilisation leading to seed and fruit formation | Flowers, Pollination and Fertilisation |
| 3.5 (practical) | Practical: investigate the conditions needed for seed germination | Seeds and Germination |
| 3.6 | How germinating seeds use food reserves until photosynthesis begins | Seeds and Germination |
| 3.8 | How the male and female reproductive systems are adapted for their functions | The Human Reproductive Systems |
| 3.13 | The roles of oestrogen and testosterone in secondary sexual characteristics | The Human Reproductive Systems |
| 3.9 | The roles of oestrogen and progesterone in the menstrual cycle | The Menstrual Cycle |
| 3.10 | The roles of FSH and LH in the menstrual cycle | The Menstrual Cycle |
| 3.11 | The role of the placenta in the nutrition of the developing embryo | The Placenta and the Amniotic Fluid |
| 3.12 | How amniotic fluid protects the developing embryo | The Placenta and the Amniotic Fluid |
| 3.14 | The genome as an organism's entire DNA; a gene as a section coding for a protein | DNA, Genes and Chromosomes |
| 3.15 | The nucleus contains chromosomes on which genes are located | DNA, Genes and Chromosomes |
| 3.16 | DNA as a double helix with paired bases A–T and C–G | DNA, Genes and Chromosomes |
| 3.17 | RNA as single-stranded, containing uracil instead of thymine | Protein Synthesis |
| 3.18 | The stages of protein synthesis: transcription and translation, mRNA, ribosomes, tRNA, codons, anticodons | Protein Synthesis |
| 3.19 | Alleles as alternative forms of genes giving rise to inherited differences | Alleles, Genotype and Phenotype |
| 3.20 | The terms dominant, recessive, homozygous, heterozygous, phenotype and genotype | Alleles, Genotype and Phenotype |
| 3.21 | The meaning of codominance | Alleles, Genotype and Phenotype |
| 3.22 | Most phenotypic features result from polygenic inheritance | Monohybrid Inheritance and Probability |
| 3.23 | Patterns of monohybrid inheritance shown with a genetic diagram | Monohybrid Inheritance and Probability |
| 3.25 | Predicting probabilities of outcomes from monohybrid crosses | Monohybrid Inheritance and Probability |
| 3.24 | How to interpret family pedigrees | Pedigrees and Sex Determination |
| 3.26 | Sex determination by one pair of chromosomes, XX and XY | Pedigrees and Sex Determination |
| 3.27 | The determination of the sex of offspring using a genetic diagram | Pedigrees and Sex Determination |
| 3.28 | Mitosis produces two cells with identical sets of chromosomes | Mitosis and Meiosis |
| 3.29 | Mitosis occurs during growth, repair, cloning and asexual reproduction | Mitosis and Meiosis |
| 3.30 | Meiosis produces four genetically different haploid gametes | Mitosis and Meiosis |
| 3.32 | The human diploid number is 46 and the haploid number is 23 | Mitosis and Meiosis |
| 3.31 | Random fertilisation produces genetic variation in offspring | Variation and Mutation |
| 3.33 | Variation within a species can be genetic, environmental or both | Variation and Mutation |
| 3.34 | Mutation as a rare, random, heritable change in genetic material | Variation and Mutation |
| 3.35 | How a change in DNA can alter the amino acid sequence of a protein and so the phenotype | How Mutations Affect Proteins |
| 3.36 | Most mutations have no effect; some have a small effect; rarely a significant one | How Mutations Affect Proteins |
| 3.37 | How ionising radiation and chemical mutagens increase the incidence of mutation | How Mutations Affect Proteins |
| 3.38 | Darwin's theory of evolution by natural selection | Natural Selection and Antibiotic Resistance |
| 3.39 | How antibiotic resistance increases in bacterial populations and why that matters | Natural Selection and Antibiotic Resistance |
The lessons
- Sexual and Asexual Reproduction — Two ways to make a new organism — one produces copies, the other produces something that has never existed before. Why any species would want both. (3.1, 3.2, 3.7)
- Flowers, Pollination and Fertilisation — Two completely different solutions to one problem — a plant that cannot move has to get its male gamete to another plant's female gamete. (3.3, 3.4)
- Seeds and Germination — What a seed needs to start growing, what it lives on before it has a single leaf — and why light is not on the list. (3.5, 3.6)
- The Human Reproductive Systems — Two systems built around the same problem — making gametes and bringing them together — and the hormones that switch them on. (3.8, 3.13)
- The Menstrual Cycle — Four hormones, two organs and one repeating question — should the uterus lining be built up, held, or let go? (3.9, 3.10)
- The Placenta and the Amniotic Fluid — An exchange surface with a constraint no other one has: two bloodstreams that must trade materials without ever mixing. (3.11, 3.12)
- DNA, Genes and Chromosomes — One molecule at four magnifications — and the pairing rule that makes it possible to copy information without understanding it. (3.14, 3.15, 3.16)
- Protein Synthesis — The instructions cannot leave the nucleus and the factory cannot go in — so a copy is sent out. Transcription, translation, and the code that connects them. (3.17, 3.18)
- Alleles, Genotype and Phenotype — Two copies of every gene, and the rules that decide which one you can see — including the case where you can see both. (3.19, 3.20, 3.21)
- Monohybrid Inheritance and Probability — A method for predicting offspring, the ratio it produces — and two honest limits on what that ratio actually tells you. (3.22, 3.23, 3.25)
- Pedigrees and Sex Determination — Reading a family tree backwards to find genotypes nobody can see — and the one cross whose answer never changes. (3.24, 3.26, 3.27)
- Mitosis and Meiosis — Two kinds of cell division solving two opposite problems — one that must copy exactly, and one that must not. (3.28, 3.29, 3.30, 3.32)
- Variation and Mutation — Three sources of difference between individuals — two that reshuffle what already exists, and one that makes something new. (3.31, 3.33, 3.34)
- How Mutations Affect Proteins — One base changes. Follow the consequences — and find out why the answer is usually nothing at all. (3.35, 3.36, 3.37)
- Natural Selection and Antibiotic Resistance — One argument in four steps — and the version of it happening in hospitals now, fast enough to watch. (3.38, 3.39)
Beyond the specification: Darwin, Mendel & the Story of Inheritance — the story-first course behind this topic, for curiosity rather than the exam.