Key term
AQA AS-Level Biology 7402
Biological Molecules
Topic overviewMonomers, polymers, condensation and hydrolysisMonosaccharides, disaccharides and glycosidic bondsAlpha and beta glucose, amylose and amylopectinHow starch, glycogen and cellulose suit their functionsCellulose microfibrils and tests for sugars and starchTriglycerides, fatty acids and phospholipid structureProperties of lipids and the emulsion testThe general structure of amino acidsPeptide bonds, polypeptides and bonds in proteinsLevels of protein structure, the biuret test and chromatographyActivation energy, induced fit and enzyme specificityEnzyme and substrate concentration and inhibitionpH, temperature, initial rates and measurement uncertaintyDNA, RNA and the components of a nucleotideBase pairing in DNA and RNAPhosphodiester bonds and the DNA double helixDoubts about DNA, base ratios and RNA structureSemi-conservative replication, helicase and DNA polymeraseSteps of replication and the Meselson-Stahl experimentATP structure, hydrolysis and resynthesisWater as a metabolite, solvent and coolantHydrogen, iron, sodium and phosphate ions
Cells
Topic overviewCell-surface membrane, nucleus and mitochondriaChloroplasts, Golgi apparatus and lysosomesRibosomes, endoplasmic reticulum, cell walls and vacuolesCell specialisation, levels of organisation and organelle rolesProkaryotic cell structure and virus particlesOptical and transmission electron microscopesScanning electron microscopes, magnification and graticulesCell fractionation, homogenisation and ultracentrifugationOrder of sedimentation, artefacts and fractionation conditionsThe cell cycle, interphase and the stages of mitosisSpindle fibres, cytokinesis and uncontrolled cell divisionBinary fission, viral replication and root tip squashesMitotic index, mitosis stages and size calculationsThe fluid-mosaic model and cholesterolSimple diffusion, facilitated diffusion and membrane proteinsOsmosis, water potential and active transportCo-transport in the ileum and adaptations for rapid transportTransport rates, dilution series and membrane permeabilityAntigens, cell recognition and phagocytosisAntigen-presenting cells, T cells and clonal selectionAntibody structure, agglutination and antigen-antibody complexesMemory cells, vaccination and active and passive immunityHIV structure and replicationAIDS, monoclonal antibodies, ELISA and clinical trials
Organisms Exchange Substances with Their Environment
Topic overviewSurface area to volume ratio, metabolic rate and calculationsGas exchange in single-celled organisms, insects and fishLeaf gas exchange, insect water loss and xerophytesTrachea, bronchi, alveoli and lung dissectionInspiration, expiration and pulmonary ventilation rateLung disease, correlation, insect tracheae and Spearman's rankDigestion of carbohydrates and lipidsEndopeptidases, exopeptidases and dipeptidasesCo-transport of amino acids, micelles and chylomicronsHaemoglobin, red blood cells and the dissociation curveCooperative binding, the Bohr effect and different haemoglobinsDouble circulation and the major blood vesselsHeart chambers, the cardiac cycle and heart dissectionArteries, arterioles, veins and capillariesTissue fluid, cardiovascular risk factors and semilunar valvesXylem structure and the cohesion-tension theoryPhloem structure, companion cells and translocationMass flow from source to sink, tracers and ringingEvaluating mass flow, potometers and transpiration rate
Genetic Information, Variation and Relationships Between Organisms
Topic overviewProkaryotic and eukaryotic DNA, chromosomes and histonesDNA in mitochondria and chloroplasts, genes and lociFeatures of the genetic code, exons and intronsGenome, proteome, mRNA and tRNATranscription, RNA polymerase and splicingTranslation at the ribosome and the role of tRNAGene mutations, mutagens and chromosome non-disjunctionMeiosis, independent segregation and crossing overMeiosis compared with mitosis and random fertilisationGenetic diversity and the spread of advantageous allelesDirectional and stabilising selectionDefining adaptations and how antibiotic resistance spreadsSelection on birth weight, aseptic technique and antimicrobialsClassifying anatomical, physiological and behavioural adaptationsDefining a species, courtship and phylogenetic classificationThe taxonomic hierarchy, binomial names and molecular evidenceSpecies richness, the index of diversity and farmingComparing genetic diversity, standard deviation and the t-test
Genetic Information, Variation and Relationships Between Organisms
- 18 subtopics
- 54 things to know
- Papers 1 and 3
What Genetic Information, Variation and Relationships Between Organisms covers
Genetic Information, Variation and Relationships Between Organisms is examined on Paper 1 of AQA Biology, which covers topics 1 to 4, and on Paper 3, which can draw on any topic. 239 recall questions across 18 subtopics.
Where it is assessed
Papers 1 and 3
Topics 1 to 4, then the synoptic paper.
Check the AQA specification ↗The 18 subtopics
Each one has its own page. AQA AS Biology students sit this topic in the first year.
- Prokaryotic and eukaryotic DNA, chromosomes and histonesRecall questions on the length and shape of DNA in prokaryotic cells and in the eukaryotic nucleus, whether it is associated with proteins, and what chromosomes and histones are.Open →
- DNA in mitochondria and chloroplasts, genes and lociRecall questions on the short, circular DNA of mitochondria and chloroplasts, genes that code for polypeptides and for functional RNA such as rRNA and tRNA, and the locus of a gene.Open →
- Features of the genetic code, exons and intronsRecall questions on base triplets and the universal, non-overlapping and degenerate genetic code, non-coding repeats between genes, exons and introns, and what these features mean for mutations.Open →
- Genome, proteome, mRNA and tRNARecall questions on the genome and the proteome, the single-stranded structure and bases of mRNA, codons, and the clover-leaf structure of tRNA with its anticodon and amino acid binding site.Open →
- Transcription, RNA polymerase and splicingRecall questions on anticodons, how RNA polymerase transcribes the template strand into mRNA, how prokaryotic and eukaryotic transcription products differ, and splicing introns out of pre-mRNA.Open →
- Translation at the ribosome and the role of tRNARecall questions on translation, how ribosomes hold mRNA and tRNA, how tRNA anticodons match codons, peptide bonds between amino acids, the ATP used, and how base sequence sets primary structure.Open →
- Gene mutations, mutagens and chromosome non-disjunctionRecall questions on gene mutations such as base deletion and substitution, why degeneracy makes some substitutions silent, mutagenic agents, and changes in chromosome number by non-disjunction.Open →
- Meiosis, independent segregation and crossing overRecall questions on the two nuclear divisions of meiosis and the haploid, genetically different cells it makes, and how independent segregation and crossing over create genetic variation.Open →
- Meiosis compared with mitosis and random fertilisationRecall questions on what separates in the first and second meiotic divisions, how meiosis and mitosis differ, random fertilisation, and calculating the possible chromosome combinations from n homologous pairs.Open →
- Genetic diversity and the spread of advantageous allelesRecall questions on genetic diversity as the number of alleles, why natural selection needs it, how new alleles arise by mutation, and how an advantageous allele becomes more frequent over generations.Open →
- Directional and stabilising selectionRecall questions on directional selection and its example in antibiotic resistance, stabilising selection and human birth weight, their effects on mean phenotype and variation, and structural and biochemical adaptations.Open →
- Defining adaptations and how antibiotic resistance spreadsRecall questions on anatomical, physiological and behavioural adaptations, and how a resistance allele arises, survives antibiotic exposure and increases in frequency in a bacterial population.Open →
- Selection on birth weight, aseptic technique and antimicrobialsRecall questions on stabilising selection in human birth weight, the aseptic techniques used when culturing microorganisms, measuring antimicrobial effectiveness by zones of inhibition, and logarithmic scales.Open →
- Classifying anatomical, physiological and behavioural adaptationsRecall questions on the three categories of adaptation and on classifying examples such as a camel's hump, migration, an Arctic fox's fur and ears, concentrated urine and nocturnal hunting.Open →
- Defining a species, courtship and phylogenetic classificationRecall questions on how a species is defined, why courtship behaviour matters for successful mating, how a phylogenetic classification arranges species into taxa, and the first ranks of the hierarchy.Open →
- The taxonomic hierarchy, binomial names and molecular evidenceRecall questions on the ranks from domain to species, writing binomial names such as Homo sapiens, and how genome sequencing and immunological comparisons clarify evolutionary relationships.Open →
- Species richness, the index of diversity and farmingRecall questions on species richness and its limits, calculating an index of diversity, and how monoculture, herbicides, pesticides and hedgerow removal reduce biodiversity and how farmland can be conserved.Open →
- Comparing genetic diversity, standard deviation and the t-testRecall questions on comparing genetic diversity using characteristics, DNA, mRNA and amino acid sequences, random sampling, mean, median, mode and standard deviation, and choosing and using statistical tests.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Process
What happens during translation?
Process
What are the key features of meiosis?
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Are prokaryotic DNA molecules associated with proteins?
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What is a chromosome?
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Is the DNA in mitochondria and chloroplasts associated with protein?
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Define a gene in terms of coding for a polypeptide.
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Define a triplet in the context of the genetic code.
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Define the proteome.
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Describe the structure of mRNA in terms of strands.
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Define the term anticodon.
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What is transcription?
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Define translation.
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What does a gene mutation involve at the molecular level?
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Define base deletion as a type of gene mutation.
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Are the daughter cells produced by meiosis genetically identical or genetically different from each other?
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What is separated during the first meiotic division, and how does this affect chromosome number?
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Compare the number and genetic composition of daughter cells produced by mitosis versus meiosis.
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What is the definition of genetic diversity?
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Why is genetic diversity necessary for natural selection to occur?
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Define directional selection.
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Give an example of directional selection in microorganisms.
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Define anatomical adaptation.
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What are physiological adaptations?
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In stabilising selection for human birth weight, which babies have the highest survival rates?
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Over generations, what happens to alleles associated with extreme birth weights?
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What are the three main categories of adaptation that organisms can possess?
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What is an anatomical adaptation?
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Why is courtship behaviour considered essential before mating can occur?
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What is a phylogenetic classification system?
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What does the first part of a binomial name indicate?
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What does the second part of a binomial name indicate?
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At what scales can biodiversity be measured?
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Define species richness.
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Apart from DNA, what other nucleic acid can be analysed to compare genetic diversity between species?
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What older method of inferring genetic differences has been replaced by gene technology?
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What are histones?
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How can a gene be defined when it does not code for a polypeptide?
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What does it mean that the genetic code is universal?
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Which four nitrogenous bases are found in mRNA?
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Along which strand of DNA does RNA polymerase move during transcription?
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How many subunits do ribosomes have and what do they bind to?
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What is a base substitution mutation?
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How many nuclear divisions occur during meiosis?
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How do mitosis and meiosis differ in their effect on chromosome number?
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Are all mutations harmful to an organism?
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What is stabilising selection?
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Define behavioural adaptation.
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Why do microbiologists work near a Bunsen flame when handling cultures?
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What is a physiological adaptation?
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How are groups organised within a phylogenetic classification?
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In binomial nomenclature, which part of the name begins with a capital letter?
Evaluation
What limitation does species richness have as a measure of biodiversity?
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Why must data be collected from random samples when quantitatively investigating variation within a species?
Take Genetic Information, Variation and Relationships Between Organisms further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Intron vs Exon
Intron: a non-coding sequence removed from pre-messenger RNA. Exon: a coding sequence retained in mature messenger RNA.
Species diversity vs Genetic diversity
Species diversity: the number of species and their relative abundance in a community. Genetic diversity: the variety of alleles within a population or species.
Directional selection vs Stabilising selection
Directional selection: selection that favours one extreme of a range and shifts the mean towards it. Stabilising selection: selection that favours the middle of a range and reduces variation about the mean.
Questions from this topic
Each one with the model answer underneath.
- 1
Describe the length of DNA molecules found in prokaryotic cells.
Model answer
Short.
- 2
What is the shape of DNA molecules in prokaryotic cells?
Model answer
Circular.
- 3
Are prokaryotic DNA molecules associated with proteins?
Model answer
No, prokaryotic DNA is not associated with proteins.
- 4
Describe the length of DNA molecules found in the nucleus of eukaryotic cells.
Model answer
Very long.
- 5
What is the shape of DNA molecules in the nucleus of eukaryotic cells?
Model answer
Linear.
- 6
What proteins are associated with DNA in the nucleus of eukaryotic cells?
Model answer
Histones.
What is inside Levo
Six ways to work the same material.
Genetic Information, Variation and Relationships Between Organisms revision questions
- Is Genetic Information, Variation and Relationships Between Organisms examined at AS in AQA Biology?
- Yes. It sits in Papers 1 and 3, which you take in the first year, so it is on the AS paper as well as counting towards the full A level.
- What does Genetic Information, Variation and Relationships Between Organisms cover in AQA AS-Level Biology?
- 18 subtopics: prokaryotic and eukaryotic dna, chromosomes and histones, dna in mitochondria and chloroplasts, genes and loci, features of the genetic code, exons and introns, genome, proteome, mrna and trna, transcription, rna polymerase and splicing, translation at the ribosome and the role of trna, gene mutations, mutagens and chromosome non-disjunction, meiosis, independent segregation and crossing over, meiosis compared with mitosis and random fertilisation, genetic diversity and the spread of advantageous alleles, directional and stabilising selection, defining adaptations and how antibiotic resistance spreads, selection on birth weight, aseptic technique and antimicrobials, classifying anatomical, physiological and behavioural adaptations, defining a species, courtship and phylogenetic classification, the taxonomic hierarchy, binomial names and molecular evidence, species richness, the index of diversity and farming and comparing genetic diversity, standard deviation and the t-test. Each one has its own page with questions and model answers.
- How is Genetic Information, Variation and Relationships Between Organisms organised?
- By the AQA 7402 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Genetic Information, Variation and Relationships Between Organisms, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
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