Inheritance, Variation and Evolution

What Inheritance, Variation and Evolution covers

Inheritance, Variation and Evolution is examined in Biology Paper 2. It covers sexual and asexual reproduction, meiosis and the advantages of each type of reproduction; DNA, the genome, nucleotides, protein synthesis and mutations; genetic terms, Punnett squares and genetic crosses; inherited disorders and sex determination; variation and evolution; selective breeding, genetic engineering, GM crops and cloning; Darwin, Lamarck, Wallace, speciation and the understanding of genetics; evidence for evolution, extinction, fossils and resistant bacteria; and the classification of living organisms.

The 23 subtopics

Each one has its own page.

• Sexual and asexual reproductionMitosis and meiosis, gametes in animals and flowering plants and their fusion at fertilisation, why sexual reproduction produces variation, and asexual reproduction from one parent by mitosis producing clones.Open →
• MeiosisHow meiosis halves the chromosome number and fertilisation restores it, where it happens, copying then two divisions giving four different gametes, and mitosis in the growing embryo.Open →
• Advantages and disadvantages of sexual and asexual reproductionVariation and natural selection as advantages of sexual reproduction, selective breeding, the speed and efficiency of asexual reproduction in stable conditions, organisms that use both such as malarial parasites, fungi and strawberries, and choosing a type of reproduction for roses, greenfly and fish farms.Open →
• DNA and the genomeNucleus, chromosome and gene by size, the double helix and DNA as a polymer, what a gene codes for, and what studying the human genome offers medicine and migration history.Open →
• DNA as a polymer of four nucleotidesThe sugar, phosphate and base of a nucleotide, the four bases A, C, G and T, three bases coding for each amino acid and how many amino acids a sequence codes for, and the alternating sugar and phosphate structure of each strand.Open →
• Protein synthesis and complementary base pairingWhich bases pair, reading the opposite strand, why the strands are complementary, ribosomes and carrier molecules building a protein, and how a changed base order changes the protein.Open →
• Mutations, protein shape and non-coding DNAHow a finished protein folds into a unique shape for its job as an enzyme, hormone or structural protein such as collagen, how most mutations leave proteins unchanged while some alter their shape, and non-coding DNA switching genes on and off.Open →
• Genetic terms, dominant and recessive allelesGametes, chromosomes, alleles, genotype and phenotype, characteristics controlled by a single gene, dominant and recessive alleles and when each is expressed, and homozygous and heterozygous organisms.Open →
• Punnett squares, probability and genetic crossesCharacteristics controlled by several genes, why a cross predicts only probabilities, ratios and percentages from 3:1 and 1:1 crosses, and worked crosses in mice, cats, peas and a recessive disorder.Open →
• Inherited disorders and sex determinationPolydactyly and cystic fibrosis, their dominant and recessive alleles, the case for and against embryo screening, the 23 chromosome pairs, XX and XY, and the chance of a boy.Open →
• VariationVariation caused by genes, the environment or both, why siblings and cloned plants differ, extensive genetic variation arising from mutations, how few variants affect the phenotype, and how a new phenotype suited to a changed environment can spread quickly.Open →
• EvolutionThe definition of evolution, natural selection and new species, why it acts on populations, simple life forms over three billion years ago, mutations as the source of variation, and the interbreeding test.Open →
• Selective breedingSelective breeding or artificial selection and its history, choosing and breeding parents over many generations, characteristics chosen in crops, farm animals, dogs and flowers, inbreeding and its problems, and the effects on variation and food production.Open →
• What genetic engineering is, and what it is used forThe definition of genetic engineering, where the new gene comes from, engineered crops and insulin from bacteria, cutting out and transferring a gene, and the benefits, objections and risks.Open →
• GM crops, their risks, and the steps of the processWhat genetically modified crops are and the insect and herbicide resistance and higher yields they give, concerns about wildlife and human health, hopes for overcoming inherited disorders, and the steps of genetic engineering using enzymes and plasmid or virus vectors at an early stage of development.Open →
• CloningTissue culture for conservation and nurseries, taking cuttings, splitting embryos for embryo transplants, and adult cell cloning, from replacing an egg cell nucleus and an electric shock to implanting the embryo, and why the clone matches the nucleus donor.Open →
• Darwin, Lamarck and the acceptance of evolutionDarwin's observations, the theory of natural selection and On the Origin of Species, why acceptance was slow, the later discovery of genes, and Lamarck's idea of inherited acquired changes.Open →
• SpeciationAlfred Russel Wallace, his joint writings with Darwin in 1858, his worldwide evidence and work on warning colouration, the impact of Darwin and Wallace's ideas, and speciation as isolated populations become genetically different until they can no longer interbreed.Open →
• The understanding of geneticsMendel's breeding experiments on plants and why their importance was missed, the observation of chromosome behaviour, the link between Mendel's units and chromosomes, units renamed genes, the structure of DNA and gene function, and gene theory as the work of many scientists.Open →
• Evidence for evolution, and extinctionThe fossil record and antibiotic resistance as evidence, the discovery of genes, what extinction means, and how environmental change, disease, new predators, competition and low variation cause it.Open →
• FossilsWhat fossils are and where they form, preservation without decay, replacement by minerals and preserved traces, why early life left few, and reading evolutionary trees and common ancestors.Open →
• Resistant bacteriaWhy bacteria evolve rapidly, how mutation and antibiotic use produce and spread resistant strains such as MRSA, slowing resistance by limiting prescriptions, completing courses and restricting farm use, and the cost and slowness of developing new antibiotics.Open →
• Classification of living organismsThe Linnaean groups from kingdom to species, binomial names and what shared groups show about relatedness, how microscopes and biochemistry changed classification, Carl Woese's three domains of archaea, bacteria and eukaryota, and placing organisms on evolutionary trees.Open →

What you need to know

Answer each one before you reveal it.

Take Inheritance, Variation and Evolution further

The same content, four other ways.

Commonly confused

Pairs that lose marks when they are blurred together.

• Dominant allele vs Recessive allele

  Dominant allele: a version of a gene that shows its effect with only one copy present. Recessive allele: a version of a gene that shows its effect only when two copies are present.

• Genotype vs Phenotype

  Genotype: the alleles an organism carries for a characteristic. Phenotype: the characteristics that an organism actually shows.

• Homozygous vs Heterozygous

  Homozygous: carrying two identical alleles for a characteristic. Heterozygous: carrying two different alleles for a characteristic.

Questions from this topic

Each one with the model answer underneath.

1. 1

   Which type of cell division produces cells that are genetically identical to one another?

   Model answer

   Mitosis produces genetically identical cells.

2. 2

   Why are the cells produced by meiosis described as non-identical?

   Model answer

   Meiosis produces cells that all differ from each other genetically, unlike mitosis, which produces identical copies.

3. 3

   What happens to the male and female gametes during sexual reproduction?

   Model answer

   They join together, or fuse, at fertilisation.

4. 4

   Name the male gamete and the female gamete in animals.

   Model answer

   The sperm cell is the male gamete and the egg cell is the female gamete.

5. 5

   Name the male gamete and the female gamete in flowering plants.

   Model answer

   Pollen is the male gamete and the egg cell is the female gamete.

6. 6

   Why does sexual reproduction produce offspring that vary?

   Model answer

   Genetic information from two parents is mixed, so the offspring are not identical to either parent or to each other.

What is inside Levo

Six ways to work the same material.

Inheritance, Variation and Evolution revision questions

What does Inheritance, Variation and Evolution cover in AQA GCSE Biology?

23 subtopics: sexual and asexual reproduction, meiosis, advantages and disadvantages of sexual and asexual reproduction, dna and the genome, dna as a polymer of four nucleotides, protein synthesis and complementary base pairing, mutations, protein shape and non-coding dna, genetic terms, dominant and recessive alleles, punnett squares, probability and genetic crosses, inherited disorders and sex determination, variation, evolution, selective breeding, what genetic engineering is, and what it is used for, gm crops, their risks, and the steps of the process, cloning, darwin, lamarck and the acceptance of evolution, speciation, the understanding of genetics, evidence for evolution, and extinction, fossils, resistant bacteria and classification of living organisms. Each one has its own page with questions and model answers.

How is Inheritance, Variation and Evolution organised?

By the AQA 8461 specification, subtopic by subtopic, so it matches the order you are taught it in.