IB Command Terms

1. IB Command Terms Group 4

2. “The command terms indicate the depth of treatment required for a given assessment statement”. • So, they indicate what is expected from you in an exam. • Becoming familiarized with the command terms will make your pass through the diploma program easier.

3. Objective 1. Demonstrate your understanding • Define • Draw • Label • List • Measure • State

4. Define: Give the precise meaning of a word, phrase or physical quantity. (a)Define the term active site of an enzyme. The site (on the surface of an enzyme) to which substrate(s) bind / the site (on theenzyme) where it catalyzes a chemical reaction

5. Draw: Represent by means of pencil lines. • “Draw a labeled graph showing a typical sigmoidal population growth curve .”

6. Label: Add labels to a diagram • Identify the following structures in the human eye. • I .Cornea........................................... • II ..Lens................................................ • III. ..Retina............................................ • IV. ..Vitreoushumour........................... • V. ...Blind spot..................................... • VI. ..Opticnerve.................................

7. List: Give a sequence of names or other brief answers with no explanation. • List four functions of proteins, giving an example of each. storage – zeatin (in cornseeds) / casein (in milk); transport – hemoglobin / lipoproteins (in blood); hormones – insulin / growth hormone / TSH / FSH / LH; structure – collagen / keratin / tubulin / fibroin;

8. Measure: Find a value for a quantity. • Measure the length of organelle X

9. State: Give a specific name, value or other brief answer without explanation or calculation. • State the function of synovial fluid in the human elbow joint. • lubrication / reduction of friction

10. Objective 2: Apply and use • Annotate • Apply • Calculate • Describe • Distinguish • Estimate • Identify • Outline

11. Annotate: Add brief notes to a diagram or graph. • “Annotate a graph showing hormone levels in the menstrual cycle.”

12. Apply: Use an idea, equation, principle, theory or law in a new situation • Which group of organisms, identified by this key, represents the Fungi? • 1 Nucleipresent .................................................................2 • No nucleipresent...............................................................A • 2 Develops from an embryo.................................................3 • Does not develop from an embryo..................................4 • 3 Cell wall present .................................................................B • No cellwall.........................................................................C • 4 Cell wall of chitin................................................................D • Cell wall of cellulose or no cell wall..................Protoctista

13. Calculate: Use an idea, equation, principle, theory or law in a new situation. • The diagram below shows the structure of a cell. Calculate the actual length of the cell, showing your working.

14. Describe: Give a detailed account • Describe passivetransportacross a biologicalmembrane. • passive transport requires no energy;molecules move down a concentration gradient;water moves by osmosis;from lower solute concentration to higher solute concentration / high water concentration to low water;small uncharged molecules move by diffusion;between phospholipid molecules;charged molecules move by facilitated diffusion;requires a protein channel ;[5]

15. Distinguish: Give the differences between two or more different items. • Distinguish between the structure of plant and animal cells. • plantcells:havecellwalls, animal cells do not;haveplastids / chloroplasts, animal cells do not;have a large central vacuole, animal cells do not;storestarch, animal cellsstoreglycogen;haveplasmodesomata, animal cells do not; • animal cells:have centrioles, plant cells do not;have cholesterol in the cell membrane, plant cells do not;plant cells generally have a fixed shape / more regular whereas animal cells are more rounded;

16. Estimate: Find an approximate value for an unknown quantity. • Estimate the population size of Rufus sparrow in the northern part of Quito Simpson diversity index D= N (N - 1)  n (n-1) N= total number of all individual organisms of all species found n= number of individuals of a particular species.

17. Identify: Find an answer from a given number of possibilities • (a) Identify the percentage of rats that remain alive in each group after 800 days. • Control: 25% (+/-3).............................................................................. • Experimental: 75% (+/ 3-)......................................................................

18. Outline: Give a brief account or summary. • (b)Outline how the graph shows the effect of energy content on longevity. less energy in experimental, then greater % survival / longevity;very young have same possibility of survival / no effect until 200 days old;more energy, then death / mortality rate higher / less surviving;valid numerical example / 50% survival level comparison;

19. Objective 3: Construct, analyse and evaluate. • Analyse • Comment • Compare • Construct • Deduce • Derive • Design • Determine • Discuss • Evaluate • Explain • Predict • Show • Sketch • Solve • Suggest

20. Analyse: Interpret data to reach conclusions

21. Comment: Give a judgment based on a given statement or result of a calculation. • Estimate, using the decay curve, the percentage of 40K atoms that remain 1875 million years after the formation of a sample.

22. Compare: Give an account of similarities and differences between two (or more) items, referring to both (all) of them throughout. • (a) Compare the changes in the intake of saturated fat with polyunsaturated fat among hunter-gatherer, agricultural and industrial populations over the whole time span. both saturated and polyunsaturates remain constant throughhunter-gatherer and agricultural societies;saturated fats rise earlier / sooner at 200 bp / beginning of industrial revolutionwhereas polyunsaturates rise later / in the last 100 years;saturated fats rise from 8–9% to 18% whereaspolyunsaturated rise from 5% to 7%;saturated always more than polyunsaturated / polyunsaturated less than saturated;

23. Construct: Represent or develop in graphical form • Construct a food web using the data table:

24. Deduce: Reach a conclusion from the information given. • Using the data in the bar chart, deduce the effect on the two cerebral hemispheres of opening only the right eye.

25. Design: Produce a plan, simulation or model. • “Design a nature reserve that would meet the needs of a species in situ (in its natural habitat) and encourage recovery.” • Design a pamphlet

26. Determine: Find the only possible answer • (ii) Determine which hemisphere is more awake when the right eye is open.

27. Discuss: Give an account including, where possible, a range of arguments for an against the relative importance of various factors, or comparisons of alternative hypotheses. • Discuss the effects of one named human activity that harms ecosystems and how it might be contained or reduced. Refer to an example other than those increasing the greenhouse effect. (8) name of relevant activity;(To obtain full marks, a candidate must include at least one ideafrom each of the following categories.) cause of the problem;another detail of the cause of the problem; effect caused by the problem / activity;another detail of the effect caused by the problem / activity;other discussion concerning anotherfeature (cost, geographical features); contained / reduced: detail how cause / problemcan be contained / reduced;another detail how cause / problem can be contained / reduced;effectiveness of one solution; conclusion; example: air pollution;others.

28. Evaluate: Assess the implications and limitations. • Evaluate whether the hypothesis that pollen in the air increases asthma attacks is supported by the data. [Source: Paul F Jamason et al., (1997) American Journal of Respiratory and Critical Care Medicine,156, pages 1781-1788]

29. Explain: give a detailed account of causes, reasons or mechanisms. • Explain the relationship between the structure and function of arteries, veins and capillaries. • ([3 max] for information on arteries)thick wall / elastic fibres to help withstand the high(er) pressure;outer fibrous coat prevents artery from rupturing under the high pressures;lumen small compared to wall thickness to maintain high pressure;except lumen large near the heart to conduct a large volume of blood;valves in aorta and pulmonary artery to preventback flow into ventricles in diastole;layers of (smooth) muscle to allow arteries to contract / elastic recoil;allows the pressure to be altered (vasoconstriction and vasodilation); • ([3 max] for information on veins)lumen always large in relation to diameter;thin wall / more collagen and fewer elastic fibres (than arteries)since pressure low(er);very little muscle since not needed for constriction;valves to prevent back flow between pulses; • ([3 max] for information on capillaries)no muscle / elastic tissue since pressure very low;endothelial layer one cell thick to allow permeability / diffusion of chemicals / tissue fluid;small diameter leads to exchange;some fenestration / pores to allow rapid diffusion;no valves since pressure very low; • [8]

30. Predict: Give an expected result

31. Show: Give the steps in a calculation or derivation

32. Sketch: Represent by means of a graph showing a line and labeled but unscaled axes but with important features (for example, intercept) clearly indicated.

33. Solve: Obtain an answer using algebraic and/or numerical methods.

34. Suggest: Propose a hypothesis or other possible answer. • Suggest a reason for the differences in chlorophyll concentration and leaf area in sun and shade leaves in these two species. [Source: D Curtis, Plant Ecology independent project, 1990]