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IB Biology Command Terms
By Wojtek
•
August 30, 2024
Understanding IB Biology command terms is essential for success in the course, as these terms determine the type of responses you need to provide in your exams. Each command term requires a distinct approach, guiding how you should present your scientific explanations. In this post, we will break down these command terms, equipping you with the information necessary to excel in the course.
IB Biology Command Terms
Define – Give the precise meaning of a word, phrase or physical quantity. For instance, if you were asked to define osmosis an answer that addresses this command term adequately would be: ''Osmosis is the net movement of water molecules across a semi-permeable membrane from a region of low solute concentration (hypotonic solution) to a region of high solute concentration (hypertonic solution) until equilibrium is reached (isotonic solution).''.
Draw – Create a diagram or graph, accurately representing key features (label unless told not to). If, for example, you were asked to draw a prokaryotic cell, you would use a pencil to create the illustration, ensuring that all key features – such as ribosomes, pili, flagella, cell membrane, cell wall, etc. – are accurately depicted and clearly labeled.
Label – Add labels to a diagram. For example, if you were asked to label the parts of a eukaryotic cell, you would identify and clearly mark each structure, such as the nucleus, mitochondria, endoplasmic reticulum, and cell membrane, on the diagram provided.
List – Provide a sequence of items or terms without detailed explanations. For instance, if you were asked to list the stages of mitosis, you would simply write: prophase, metaphase, anaphase, and telophase, without further explanation or description.
Measure – Determine the value or quantity of something, often requiring calculation or use of an instrument. For example, in an IB Biology exam, if you were asked to measure the length of a leaf, you would use a ruler to accurately determine and record the measurement in centimeters or millimeters.
State – Give a brief answer or specific piece of information, usually without further detail. For instance, if you were asked to state the function of the mitochondrion, you would simply respond: ''The mitochondrion is the site of aerobic respiration and ATP production in the cell.''.
Annotate – Add brief notes to a diagram or graph to clarify specific features. For example, if you were asked to annotate a diagram of the human heart, you would label key structures like the ventricles, atria, and valves, and include short notes explaining their functions, such as 'Left ventricle: pumps oxygenated blood to the body.
Apply – Use an idea, equation, principle, theory or law in a new situation. For instance, if you were asked to apply the principles of natural selection to explain the development of antibiotic resistance in bacteria, you would describe how genetic variation and selective pressure from antibiotics lead to the survival and reproduction of resistant strains.
Calculate – Find a numerical answer showing the relevant workings. For example, if you were asked to calculate the magnification of a microscope image, you would divide the size of the image by the actual size of the specimen, providing both the calculation and the final magnification value.
Describe – Give a detailed account pattern, or process, covering all relevant points. For example, if you were asked to describe the process of transcription, you would explain each step, including the breaking of the hydrogen bonds, the alignment of free complementary nucleotides, the joining of the nucleotides in a 5' – 3' direction, the detachment of the synthesized RNA strand, and the reformation of the double helix.
Distinguish – Show the differences between two or more concepts or items, making clear distinctions. For example, if you were asked to distinguish between prokaryotic and eukaryotic cells, you would mention differences such as ribosome size, the presence of membrane-bound organelles, or the nucleus.
Estimate – Find an approximate value for an unknown quantity. For example, if you were asked to estimate the rate of enzyme activity from a graph showing the reaction rate at different substrate concentrations, you would approximate the rate at a given concentration by analyzing the trend and reading from the graph.
Identify – Find an answer from a given number of possibilities. For instance, if you were presented with an image of an eukaryotic cell and asked to identify which one is involved in protein synthesis, you would select the ribosome from the options provided.
Outline – Give a brief account or summary. For example, if you were asked to outline the stages of cellular respiration, you would summarize them as: glycolysis, the link reaction, the Krebs cycle, and the electron transport chain, briefly noting the primary function of each stage without going into too much detail.
Analyse – Interpret data to reach conclusions. For example, if you were given a graph showing the effect of temperature on enzyme activity, you would analyze the data to determine how temperature influences the enzyme's rate of reaction, identifying trends and drawing conclusions about the optimal temperature for enzyme activity.
Comment – Give a judgment based on a given statement or result of a calculation. For example, if you were given data showing a decrease in the rate of cellular respiration under low oxygen conditions, you might comment on how this aligns with the role of oxygen as the final electron acceptor in the electron transport chain and discuss the implications for ATP production and cellular energy metabolism.
Compare – Give an account of similarities and differences between two (or more) items, referring to both (all) of them throughout. For example, if you were asked to compare the structures of DNA and RNA, you would describe how both are nucleic acids involved in genetic information but differ in their sugar components, their number of strands, and their roles in the cell.
Construct – Represent or develop in graphical form. For instance, if you were asked to construct a phylogenetic tree, you would create a diagram that visually represents the evolutionary relationships between different species, with branches indicating common ancestors and showing how species have diverged over time.
Deduce – Reach a conclusion from the information given. For example, if you were provided with data showing that the reaction rate of an enzyme increases with temperature up to a certain point and then decreases, you might deduce that the enzyme has an optimal temperature range for activity and that temperatures above this range lead to denaturation of the enzyme.
Derive – Manipulate a mathematical relationship(s) to give a new equation or relationship. For example, to calculate the actual size of a specimen using the magnification formula, you would derive the actual size from the magnification and image size by rearranging the formula.
Design – Produce a plan, simulation or model. For example, if you were asked to design an experiment to determine the translocation rate of nutrients in plants you would outline a plan that includes radioactively labeling carbon dioxide, placing aphids at different lengths of the plant, severing the aphids' stylets, and recording the time at which radioactively-labeled sugars were found at different distances.
Determine – Find the only possible answer. For instance, if you were given a set of experimental data showing a specific enzyme's activity at different pH levels and asked to determine the optimal pH for that enzyme, you would identify the pH level at which the enzyme shows the highest activity.
Discuss – Give an account including, where possible, a range of arguments for and against the relative importance of various factors, or comparisons of alternative hypotheses. For instance, if you were asked to discuss the impact of genetic and environmental factors on human height, you would address how genetic predisposition, such as inherited alleles, and environmental factors, such as nutrition and overall health, each contribute to an individual's height.
Evaluate – Assess the implications and limitations. For example, if you were asked to evaluate the effectiveness and impact of GMO crops you would discuss the benefits and drawbacks of GMO crops, mentioning advantages such as increased crop yield, enhanced nutritional content, and pest resistance, as well as downsides such as health reactions, reduction of biodiversity, or the evolution of herbicide-resistant weeds.
Explain – Give a detailed account of causes, reasons or mechanisms. For example, if you were asked to explain how enzyme activity is affected by pH, you would detail the mechanism by which pH changes the shape of the enzyme's active site, affecting substrate binding.
Predict – Give an expected result. For example, if you were asked to predict the effect of increasing temperature on the rate of enzyme-catalyzed reactions, you would anticipate that, up to a certain point, the reaction rate will increase with temperature due to more frequent collisions between enzyme and substrate. However, you would also predict that beyond an optimal temperature, the rate will decrease as the enzyme denatures and loses its functional shape.
Show – Give the steps in a calculation or derivation. For instance, if you were asked to show the calculation of magnification of a microscope image, you would first measure the size of the image using a ruler. Next, you would note the actual size of the specimen from provided data. Then, apply the magnification formula.
Sketch – Make a simple, freehand drawing showing the essential features, without detailed accuracy or measurement. For example, if you were asked to sketch a general plant cell, you would draw the basic outline of the cell, including essential structures like the cell membrane, nucleus, chloroplasts, and vacuole, without focusing on precise proportions or detailed internal structures.
Solve – Obtain an answer using algebraic and/or numerical methods. For instance, if you were asked to solve for the actual size of a specimen given its image size and the total magnification, you would divide the image size by the magnification.
Suggest – Propose a hypothesis or other possible answer. For example, if you were asked to suggest a reason for a decrease in plant growth when exposed to high levels of salt, you might propose the hypothesis that high salt concentrations create a hypertonic environment around the plant roots, leading to reduced water uptake due to osmotic stress.
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