Inheritance, variation and evolution – GCSE AQA Higher Biology revision notes

What this topic covers

Inheritance, variation and evolution has 4 subtopics:

• Reproduction
• Variation and evolution
• The development of understanding of genetics and evolution
• Classification of living organisms

Inheritance, variation and evolution lessons by subtopic

27 lessons, grouped by subtopic.

Reproduction

• DNA Structure and the Genome: Learn about the structure of DNA as a double helix polymer, how genes code for proteins, and understand what the genome is and its importance for medicine.
• Applications of Genome Research: Explore how understanding the human genome is used to search for disease genes, understand inherited disorders, and trace human migration patterns throughout history.
• Genetic vocabulary and basic inheritance (Part 1/2): Learn key genetic terms including gamete, chromosome, gene, allele, dominant, recessive, homozygous, heterozygous, genotype and phenotype. Understand how alleles control characteristics and the difference between dominant and recessive alleles.
• Genetic vocabulary and basic inheritance (Part 2/2): Learn key genetic terms including gamete, chromosome, gene, allele, dominant, recessive, homozygous, heterozygous, genotype and phenotype. Understand how alleles control characteristics and the difference between dominant and recessive alleles.
• Genetic crosses and Punnett squares: Explore single gene inheritance using examples like fur colour in mice and colour blindness. Learn to construct and interpret Punnett squares, understand probability in genetic crosses, and use ratios to predict outcomes.
• Multiple gene inheritance: Understand that most characteristics are controlled by multiple genes rather than single genes, and appreciate the complexity of real inheritance patterns compared to simple single gene crosses.
• Gametes in Sexual Reproduction: Explore the specialized reproductive cells in animals and flowering plants, understanding how sperm, egg, and pollen cells enable sexual reproduction through the fusion of male and female gametes.
• Sexual vs Asexual Reproduction and Cell Division: Compare sexual and asexual reproduction, examining how meiosis creates genetic variety in sexual reproduction while mitosis produces identical clones in asexual reproduction, and understand the genetic consequences of each reproductive strategy.

Variation and evolution

• The Process of Genetic Engineering: Learn what genetic engineering is and how genes are isolated, inserted into vectors, and transferred to cells. Understand the main steps in the genetic engineering process and how organisms develop with desired characteristics.
• Applications of Genetic Engineering: Explore real-world uses of genetic engineering including GM crops with improved disease resistance and yields, and bacteria engineered to produce human insulin. Discover how genetic modification could help treat inherited disorders.
• Benefits, Risks and Ethics of Genetic Engineering: Evaluate the potential benefits and risks of genetic engineering in agriculture and medicine. Examine concerns about GM crops' effects on wildlife and human health, and understand why some people object to genetic modification.
• What is Evolution?: Understanding evolution as changes in inherited characteristics over time and how all species evolved from simple life forms through natural selection.
• How Evolution Works Through Natural Selection: Exploring the mechanism of natural selection and how it leads to evolution by selecting variants with advantageous phenotypes for their environment.
• Formation of New Species: Understanding how populations become so different that they can no longer interbreed to produce fertile offspring, resulting in the formation of new species.
• Animal Cloning Techniques: Learn about nuclear transfer cloning and embryo transplants - two methods used to create genetically identical animals.
• Plant Cloning Methods: Explore tissue culture and cuttings - two techniques used to produce identical plants for commercial and conservation purposes.

The development of understanding of genetics and evolution

• Mendel's Revolutionary Discovery: Explore Gregor Mendel's groundbreaking breeding experiments on plants in the mid-19th century and discover why his work on inheritance 'units' wasn't recognised until after his death.
• From Chromosomes to Gene Theory: Trace the scientific journey from observing chromosome behaviour in the late 19th century to understanding DNA structure and gene function, leading to the development of modern gene theory.
• What are fossils and how are they formed?: Students learn what fossils are and explore the three main ways fossils can form: from parts that haven't decayed, through mineral replacement, and as preserved traces like footprints and burrows.
• Fossils as evidence for evolution: Students discover why the fossil record is incomplete due to soft-bodied organisms and geological activity, and learn how fossils provide evidence for evolutionary change over time, including interpreting evolutionary trees and data.
• Darwin and Wallace: Developing the Theory of Evolution: Explore how Charles Darwin and Alfred Russell Wallace independently developed the theory of evolution by natural selection, their collaboration in 1858, and the publication of On the Origin of Species in 1859.
• Wallace's Contributions and the Impact on Biology: Investigate Alfred Wallace's worldwide evidence gathering, his work on warning colouration and speciation theory, and examine how evolutionary ideas transformed the field of biology.
• The Process of Speciation: Learn the step-by-step process that leads to the formation of new species, building on the foundational work of Wallace and modern understanding of speciation mechanisms.
• Darwin's Theory of Natural Selection: Explore how Darwin developed his revolutionary theory of evolution by natural selection, including the key principles of variation, survival of the fittest, and inheritance of favourable characteristics.

Classification of living organisms

• The Three-Domain System: Explore the modern three-domain classification system developed by Carl Woese, covering Archaea (primitive bacteria in extreme environments), Bacteria (true bacteria), and Eukaryota (including protists, fungi, plants and animals). Understand how advances in microscopy and biochemistry led to this new classification model.
• The Linnaean Classification System: Learn about Carl Linnaeus's traditional classification system using seven hierarchical levels: kingdom, phylum, class, order, family, genus and species. Understand the binomial naming system and practice using the Linnaean system to classify organisms.
• Evolution of Classification and Evolutionary Trees: Examine how biological developments have impacted classification systems over time and discover how scientists use evolutionary trees to show relationships between organisms using current classification data and fossil evidence.

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More in this course

Go back to the full GCSE AQA Higher Biology topic list, or practise this topic with past-paper questions.