• 04 Ecology

    Energy flow 4.2

    This topic is all about the way that energy from sunlight is trapped by photosynthesis and then passed from organism to organism in a food web.  We can call this the transfer of energy within food webs. Being able to describe the path taken by the en…

  • 03 Genetics SL

    Chromosomes 3.2

    …ryotes. The number of chromosomes is a characteristic of eukaryote species. The structure and shape of the chromosomes in an organism can also give information about the genetic diseases, gender and about genome size. Karyograms are used to display t…

  • 07 Nucleic acids AHL

    Nucleic acids 7.1 HL

    …e to answer a difficult IB question about DNA replication it is useful to break down the task into smaller steps. Here is an example. Describe the process of DNA replication (8 marks) Step 1: From your revision notes you might be able to list structu…

  • Paper 2 style Exam questions

    …question comes with a few notes about the topic and a model answer.  Before you attempt the questions,... *** page content, list of pages using the snippet ***  …

  • 10 Genetics AHL

    Meiosis 10.1 HL

    …ils you find difficult to understand. Gallery: CS Movement 11.2 Mode: carousel Thumb width: 48px Layout: row Summary Summary list for 10.1 Meiosis Crossing over DNA replication makes a second chromatid in each chromosome in interphase before meiosis.…

  • Option B - Biotechnology

    …mid of Agrobacterium tumefaciens to introduce glyphosate resistance into soybean crops. Novel products can be produced using genetically modified crop plants. E.g. bulk production of Hepatitis B vaccine in tobacco plants and  Amflora potato (Solanum…

  • Option A - Neurobiology

    …phalogram images and recognise abnormal patterns that can be used to diagnose conditions, e.g. Angelman syndrome, which is a genetically inherited condition. Analyse correlations between body size and brain size in different animals. A3 Perception of…

  • 03 Genetics SL

    Genetic Modification 3.5

    …their applications and some of the ethical dilemmas with the use of this technology. Cloning of animals after they have been genetically modified is an example case. Key concepts Learn and test your biological vocabulary for 3.5 Genetic modification…

  • 05 Evolution

    Classification of biodiversity 5.3

    …s     Uterus b) Explain what is meant by the term “binomial name” (2 marks)       The generic name of the genus to which the organism belongs     followed by the specific name distinguishing the species c) Microcebus is the name given to all the mous…

  • 07 Nucleic acids AHL

    Transcription 7.2 HL

    …es in eukaryotes. Eukaryotes modify mRNA after transcription. Splicing of mRNA increases the number of different proteins an organism can produce. Gene expression is regulated by proteins that bind to specific base sequences in DNA. E.g. methylation.…

  • 08 Metabolism AHL

    Metabolism 8.1 HL

    …ay. Enzymes catalyse chemical reactions by lowering the activation energy. Competitive inhibitors Competitive inhibitors for example in medicine - ethanol and Fomepizole used as competitive inhibitors for antifreeze poisoning. Non-competitive inhibit…

  • 11 Animal physiology AHL

    …smoregulation 11.4 Sexual reproduction 11.1 Antibody production and vaccination Cells & pathogens The surface of cells of an organism has unique molecules. Pathogens can be species-specific or can cross species barriers. Antibody production involves…

  • 03 Genetics SL

    …(eg. in paternity disputes) Genetic modification is the transfer of genes from one species to another. Clones are groups of genetically identical organisms, derived from a single original parent cell. Many plant species and some animal species have…

  • 01 Cell biology

    Introduction to cells 1.1

    …n a cell’s genome and not others. Multicellular organisms can be bigger than unicellular organisms. Large size can allow the organism to reduce their metabolic rate. Large organisms can be more independent with regards to the environment / they can m…

  • 10 Genetics AHL

    Gene pools and speciation 10.3 HL

    …Begin with defining the term in the question. Polyploid organisms have three or more complete sets of chromosomes (a diploid organism has two sets of chromosomes). The gametes of the polyploid will not have the haploid number of chromosomes of the or…

  • 11 Animal physiology AHL

    Movement 11.2 HL

    …ystem       Click to open. The musculoskeletal system has several roles, you need to know these roles and be able to give an example of each role. Answer the question on paper and compare your answer to the model answer. List, with an example for eac…

  • 02 Molecular biology

    Carbohydrates & Lipids 2.3

    …humans relates to function. For long-term energy storage in humans lipids are better than carbohydrates. Potatoes have been genetically modified to reduce the level of amylose to produce a more effective adhesive. Evaluate the conflicting evidence f…

  • 02 Molecular biology

    …humans relates to function. For long-term energy storage in humans lipids are better than carbohydrates. Potatoes have been genetically modified to reduce the level of amylose to produce a more effective adhesive. Skills Evaluate the conflicting evi…

  • 06 Human physiology

    Hormones and reproduction 6.6

    …nction of structures. State that scientific discoveries often follow developments in equipment, and illustrate this with the example that microscopes were not available for William Harvey’s investigation of sexual reproduction in deer so he failed to…

  • 02 Molecular biology

    Photosynthesis 2.9

    …topic. Answer the question below on a piece of paper, then check your answer with the model answer below. Explain how three named environmental factors can affect the rate of photosynthesis. (6 marks)  Examiner's hint: Name the factor and give t…

  • Option C - Ecology

    …actices, including the effect of population size, age and reproductive status. Model the sigmoid growth curve using a simple organism such as yeast or species or duckweed. C6 Nutrient cycles - HL Understanding(s) Atmospheric nitrogen is converted to…

  • 07 Nucleic acids AHL

    …es in eukaryotes. Eukaryotes modify mRNA after transcription. Splicing of mRNA increases the number of different proteins an organism can produce. Gene expression is regulated by proteins that bind to specific base sequences in DNA. - eg. methylation…

  • 01 Cell biology

    Cell division 1.6

    …arousel Thumb width: 48px Layout: row Summary Summary list for 1.6 Cell division Mitosis is division of the nucleus into two genetically identical daughter nuclei. Chromosomes condense by supercoiling during mitosis. Cytokinesis occurs after mitosis…

  • 01 Cell biology

    …al. The origin of eukaryotic cells can be explained by the endosymbiotic theory. Mitosis is division of the nucleus into two genetically identical daughter nuclei. Chromosomes condense by supercoiling during mitosis. Cytokinesis occurs after mitosis…

  • 03 Genetics SL

    Genes 3.1

    …er by one or only a few bases". New alleles are formed by mutation. A genome is, "the whole of the genetic information of an organism." The entire base sequence of human genes was sequenced in the Human Genome Project. The Genbank® database can be us…

  • 01 Cell biology

    The origin of cells 1.5

    …at cells can survive inside other cells. Chloroplasts and mitochondria have double membranes which supports the idea that an organism with a single membrane was engulfed and surrounded by a host membrane its vesicle. Free living organisms have DNA, a…

  • 11 Animal physiology AHL

    Antibody production & vaccination 11.1 HL

    …ayout: row text Summary Summary list for 11.1 Antibody production & vaccination Cells & pathogens The surface of cells of an organism has unique molecules. Pathogens can be species-specific or can cross species barriers. Antibody production involves…

  • 11 Animal physiology AHL

    Sexual reproduction 11.4 HL

    …ood, the smaller the size of each embryo. Delayed implantation of the embryo can increase gestation time. Other factors with example from the data can gain marks   Extra exam question on fertilisation in mammals.     Click to open. The understanding…

  • 09 Plant biology AHL

    Transport in xylem 9.1 HL

    …ils you find difficult to understand. Gallery: CS Movement 11.2 Mode: carousel Thumb width: 48px Layout: row Summary Summary list for 9.1 Transport in xylem Leaf stomata & transpiration Leaves are adapted to absorb carbon dioxide from the air therefo…

  • 01 Cell biology

    Membrane structure 1.3

    …ions. In an answer to a 'describe' question don't just list the functions, describe that function too, giving an example if possible. Click the "+" to reveal a model answer. Model answer Describe three functions of membrane proteins. (4)…

  • 01 Cell biology

    Membrane transport 1.4

    …ils you find difficult to understand. Gallery: CS Movement 11.2 Mode: carousel Thumb width: 48px Layout: row Summary Summary list for 1.4 Membrane transport Particles move across membranes by simple diffusion, facilitated diffusion, osmosis and activ…

  • 02 Molecular biology

    Water 2.2

    …ils you find difficult to understand. Gallery: CS Movement 11.2 Mode: carousel Thumb width: 48px Layout: row Summary Summary list for 2.2 Water  Hydrogen bonds form between polar water molecules. This force give water special properties, e.g. cohesiv…

  • 05 Evolution

    Cladistics 5.4

    …ladograms including humans and other primates. Appreciate that in the light of new evidence some cladograms are changed. For example the reclassification of the figwort family using evidence from cladistics. Mindmaps These diagram summaries cover the…

  • 05 Evolution

    Natural selection 5.2

    …ow and reproduce quickly This rapid growth will lead to an increase in the population of antibiotic resistant bacteria. This example of student work explains some of the concepts of natural selection but the phrases don't link the causes to their…

  • 05 Evolution

    Evidence for evolution 5.1

    …ird wing and the human arm both have a humerus, ulna and a radius bone. Both limbs also have several wrist bones They are an example of homologous structures - evolving from a single origin. Differences There are only three "finger bones" in the bird…

  • 01 Cell biology

    Ultrastructure of cells 1.2

    …s it would be seen in an electron micrograph of a leaf. (4)   Click the "+" to reveal a model answer Model answer This is an example of a student diagram, drawn in an exam.  It is not perfect, but there are clearly drawn organelles which show quite r…

  • 04 Ecology

    Carbon Cycle 4.3

    …abelled fossilisation. Fossil fuels linked to carbon dioxide in the atmosphere with an arrow labelled combustion. Here is an example of a student answer which scores 4/4 There are no mistakes, three new reservoirs, each with an arrow and two extra ar…

  • 04 Ecology

    Species and communities 4.1

    …strial ones. Test for association between two species using the chi-squared test with data obtained by quadrat sampling. For example An ecosystem chosen where varying factors affect the distribution of the chosen species. Random quadrat sampling shou…

  • 09 Plant biology AHL

    Transport in phloem 9.2 HL

    …the sink. Companion cells have dense cytoplasm with many mitochondria so that they can supply resources to phloem cells, for example ATP for active transport of sucrose. Companion cells actively transport sucrose into phloem cells (sieve tubes) at th…

  • 09 Plant biology AHL

    Reproduction in plants 9.4 HL

    …linate flowers or to disperse seeds). Flowers and fruits are both adapted to their vectors of pollination and dispersal, for example petal colours and hooked fruits. The relationship between the animal vector and the plant is usually mutualistic. Tho…

  • 03 Genetics SL

    Inheritance 3.4

    …ils you find difficult to understand. Gallery: CS Movement 11.2 Mode: carousel Thumb width: 48px Layout: row Summary Summary list for topic 3.4 Inheritance Mendel experiments with pea plants showing his rules of inheritance. Gametes are haploid so co…

  • 09 Plant biology AHL

    Growth in plants 9.3 HL

    …ils you find difficult to understand. Gallery: CS Movement 11.2 Mode: carousel Thumb width: 48px Layout: row Summary Summary list for 9.3 Growth in plants Meristems and growth Plant meristems are undifferentiated cells which allow indeterminate growt…

  • 07 Nucleic acids AHL

    Translation 7.3 HL

    …ils you find difficult to understand. Gallery: CS Movement 11.2 Mode: carousel Thumb width: 48px Layout: row Summary Summary list for topic 7.3 Translation Three stages of translation Initiation is the assembly of the components (large and small ribo…

  • 03 Genetics SL

    Meiosis 3.3

    …ils you find difficult to understand. Gallery: CS Movement 11.2 Mode: carousel Thumb width: 48px Layout: row Summary Summary list for topic 3.3 Meiosis Meiosis produces four haploid nuclei from one diploid nucleus. Haploid nuclei allow a life cycle w…

  • 11 Animal physiology AHL

    Kidney and osmoregulation 11.3 HL

    …ils you find difficult to understand. Gallery: CS Movement 11.2 Mode: carousel Thumb width: 48px Layout: row Summary Summary list for Kidney and osmoregulation 11.3 Control of water balances in different animals Some animals are osmoconformers - thei…

  • Start here

    …videos explain the understandings and help demonstrate skills or applications. Summary lists A short and clear bullet point list of the understandings in the topic. Useful as checklists, and for revision planning. Mindmaps These diagrams summarise t…

  • 04 Ecology

    Climate change 4.4

    …ils you find difficult to understand. Gallery: CS Movement 11.2 Mode: carousel Thumb width: 48px Layout: row Summary Summary list for topic 4.4 Climate change Details of the carbon cycle are assumed (from 4.3) In aquatic ecosystems carbon is present…

  • Option D Human physiology

    …the reduction of stomach acid secretion by proton pump inhibitor drugs. Understand dehydration due to cholera toxin. Use the example of Helicobacter pylori infection as a cause of stomach ulcers. D3 The Liver The functions of the liver removes toxins…

  • 02 Molecular biology

    Molecules to metabolism 2.1

    …part of metabolism that forms large macromolecules from monomers Anabolism joins monomer molecules by condensation reactions Example: Glucose is made into Starch, amino acids are joined to form polypeptides. Catabolism is the breaking down of large c…

  • 10 Genetics AHL

    Inheritance 10.2 HL

    …– give reasons. Begin with defining the terms in the question Examples often help in questions requiring an explanation. The example may itself gain credit and may also help you in providing an explanation. In continuous variation there is a range of…