Key term
Eduqas A-Level Biology A400QS
Biological Molecules
Cell Structure and Organisation
Cell Membranes and Transport
Enzymes
Nucleic Acids and Their Functions
Importance of ATP
Photosynthesis
Respiration
Microbiology
Population Size and Ecosystems
Topic overviewPopulation growth and its measurementThe population growth curve and carrying capacityDensity dependent and density independent factorsSampling abundance and distributionEcosystems, habitats and communitiesEnergy transfer and pyramids of biomassSuccessionDecomposition and the carbon cycleThe nitrogen cycle and human interventionEutrophication and the effects of drainage
Human Impact on the Environment
Classification and Biodiversity
Topic overviewThe need for classification and the taxonomic hierarchyThe three domain and five kingdom systemsCharacteristic features of the five kingdomsAssessing relatedness by physical features and biochemistryThe species concept and the binomial systemBiodiversity, adaptation and natural selectionMeasuring biodiversity in a habitatGenetic and molecular measures of biodiversity
Mitosis and Meiosis
Sexual Reproduction in Humans
Sexual Reproduction in Plants
Inheritance
Variation and Evolution
Application of Reproduction and Genetics
Topic overviewThe Human Genome Project, other sequenced genomes and genomics in healthcareScreening embryos, stem cells and the ethical issuesGenetic fingerprinting, PCR and electrophoresis in forensic workRecombinant DNA and the production of human insulinGenetically modified crops and gene therapy
Adaptations for Gas Exchange
Topic overviewSurface area to volume ratio and gas exchange in small organismsSpecialised respiratory surfaces and the need for ventilationGills and counter current flow in bony fishThe human breathing system and its histologyVentilation and gas exchange in humansThe insect tracheal systemThe angiosperm leaf, stomata and gas exchange
Adaptations for Transport
Topic overviewVascular systems compared across animal groupsThe mammalian heart and blood vesselsThe cardiac cycle and its controlBlood, haemoglobin and dissociation curvesThe Bohr effect, chloride shift and tissue fluidThe root and the uptake of waterThe endodermis and the entry to the xylemXylem, transpiration and cohesion-tensionThe potometer and xerophytes and hydrophytesPhloem and translocation
Adaptations for Nutrition
Homeostasis and the Kidney
The Nervous System
Immunology and Disease: Disease and Its TransmissionImmunology
Immunology and Disease: AntibioticsImmunology
Immunology and Disease: The Immune ResponseImmunology
Human Musculoskeletal Anatomy: Skeletal TissuesMusculoskeletal
Topic overviewCartilage and its three typesThe composition and functions of compact boneBone remodelling and the Haversian systemRickets, osteomalacia, osteoporosis and brittle bone diseaseThe structure of skeletal muscleThe sliding filament theoryFast and slow twitch fibres, and energy for contraction
Human Musculoskeletal Anatomy: Structure and Function of the SkeletonMusculoskeletal
Human Musculoskeletal Anatomy: JointsMusculoskeletal
Neurobiology and Behaviour: The BrainNeurobiology
Neurobiology and Behaviour: NeuroscienceNeurobiology
Variation and Evolution
The Hardy-Weinberg principle
- 3 things to know
- Component 2
Overview
Hardy-Weinberg equation relating the two allele frequencies, hardy-Weinberg equation relating the genotype frequencies and four conditions under which the Hardy-Weinberg principle applies.
What you need to know
Answer each one before you reveal it.
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Key term
State the Hardy-Weinberg equation relating the two allele frequencies.
Key term
State the Hardy-Weinberg equation relating the genotype frequencies.
Questions from this subtopic
Each one with the model answer underneath.
- 1
What does the Hardy-Weinberg principle state?
Model answer
It states that the allele frequencies of a population remain constant from one generation to the next, provided that certain conditions are met.
- 2
State the Hardy-Weinberg equation relating the two allele frequencies.
Model answer
p + q = 1, in which p is the frequency of the dominant allele and q that of the recessive allele.
- 3
State the Hardy-Weinberg equation relating the genotype frequencies.
Model answer
p² + 2pq + q² = 1.
- 4
What does each term of the genotype equation represent?
Model answer
p² is the proportion of homozygous dominant individuals, 2pq the proportion of heterozygotes, and q² the proportion of homozygous recessives.
- 5
Why does the frequency of the recessive phenotype give q² directly?
Model answer
Only individuals homozygous for the recessive allele show that phenotype, so their proportion is the square of the recessive allele frequency.
- 6
One person in 400 shows a recessive condition. Calculate the frequency of the recessive allele.
Model answer
q² is 1 divided by 400, which is 0.0025, so q is the square root of 0.0025, which is 0.05.
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