Command terms in IB BiologyAll IB Biology questions and assessment statements are built around these command terms given in page

11 and 12 of the IB Biology subject guide(your syllabus).

These terms in questions give you an idea of what is expected of you.

Underline the command terms in the exam!

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Objective 1

• Demonstrate an understanding of:• Scientific facts and concepts• Scientific methods and techniques• Scientific terminology• Methods of presenting scientific information• Define Draw Label• List Measure State

Define:

• Give the precise meaning of a word, phrase or physical quantity

• Example: Define Species.

• A species is a group of organisms that can interbreed and produce fertile offspring.

Draw and Label• Represent by means of clear, dark pencil lines (no coloring needed)

and add labels• Example: Draw and label a diagram of the structure of a motor neuron

Label• Add labels to a

diagram• Example: Label the parts of a motor

neuron

library.kiwix.org

A

B C

D

E

FG

H

List• Give a sequence of names or other brief

answers with no explanation• Examples:• List three functions of lipids• List two examples of fibrous proteins• List seven levels in the hierarchy of taxa• (use mnemonics to remember the order here

– King Philip Came Over For a Good Sphagetti)

Measure• Find a value for a quantity• Use a ruler, present your answers in metric, SI units

• Example: Measure the length of the specimen

• Generally you will need to calculate from a measurement, rather than measure directly.

onearth.org

State

• Give a specific name, value or other brief answer without explanation or calculation

• Example:• State the composition and the function of the

plant cell wall.

Objective 2

• APPLY AND USE:• Scientific facts and concepts• Scientific methods and techniques• Scientific terminology to communicate

effectively appropriate method to present scientific information

• Annotate Apply Calculate Describe Distinguish Estimate Identify Outline

AnnotateAdd brief notes to a diagram or graph

In addition to labelling, some explanation/causes must be given

Example: Annotate a graph showing hormone levels in menstrual cycle

FSH and LH peak causing ovulation

FSH and LH stimulate development of oocyte

Oestrogen thickens endometrium

ProgesteroneMaintains endometriumInhibits FSH and LH

Pritamaulipas.org.mx

Apply

• Use an idea, equation, principle, theory or law in a new situation

• Example: Apply the dichotomous key to identify the flowering plant:

• 1.reproduce by means of seeds go to 2Reproduce by means of spores go to 3• 2. Seeds are made in cones ASeeds are made in fruits B• 3.Spores are made in capsule C Spores are made under leaves D

Calculate• Find a numerical answer showing the relevant

stages in the working• Example: Calculate the magnification of the

image of the prokaryote

Show your working!Use the correct SI unit!

DescribeGive a detailed account

Example:Describe the metabolic events of germination

in a typical starchy seed.

•‘Describe’ is not same as ‘explain’•Pay attention to the marks available for the question•Descriptions can be of processes or of parts of a data or graph

Distinguish

• Give the differences between two or more different terms

• Example:• Distinguish between antigens and antibodies

• No need to present similarities• Look for as many differences as there are

marks for the questions

Estimate

• Find an appropriate value for an unknown quantity

• Can be from graphical questions

Identify

• Find an answer from a given number of possibilities

Pick one single answer‘Identify’ can be used for part of diagram or graph

Example:

“Identify the response time of group 2 on day 31 of the study.”

Resp

onse

tim

e

(secs

)

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“Identify the group with the largest difference in response time from day 2 to day 31.”

Outline

• Give a brief account or summary

• Example: . Outline the international system used for naming species of living organisms. (4 marks)

• binomial system • devised by Linnaeus • the first name is the genus name and the second name is the species name • genus name can be abbreviated, upper case for first letter of genus name and the

rest of the binomial is lower case • Homo sapiens is the binomial of humans • first published name is the correct one • local / colloquial names can be very confusing / helps international communication

• Outline is a step-by-step summary or account without reasons or explanation• Present your answers neatly and clearly to get full marks

Objective 3

• Construct, analyse and evaluate:• Hypotheses, research questions and

predictions• Scientific methods and techniques• Scientific explanations

AnalyseInterpret data to reach conclusions

Read the data thoroughly and underline the important words Use the data to reach the conclusion

Pay attention to marks available

Example:“Analyse the results of this experiment.”

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Comment

• Give a judgment based on a given statement or result of a calculation

Compare• Give an account of similarities and differences between two or

more items referring to both (all) of them throughout. Example: Compare the structures of prokaryotic and eukaryotic

cells. 5 marks • DNA: P: naked/loop of DNA; E: associated with

protein/histones/nucleosomes/DNA in chromosomes • location of DNA: P:no nucleus; E: within a nucleus/nuclear

membrane • membrane bound organelles: P: none; E: present • ribosomes: P: 70S ; E: 80S • plasma membrane: P & E: same structure within both groups • respiratory structures: P: no mitochondria; E: mitochondria • pili: P: pili present E: pili absent; • plasmids: P: plasmids (sometimes) present E:plasmids absent; • flagella: P: flagella solid E: flagella flexible/membrane-bound

CONSTRUCT• Represent or develop in graphical form• Construct a pyramid of energy

for this grassland:The total solar energy received by a grassland is 4 × l05 kJ m–2 y–1. The net production of the grassland is 4.5 × 102 kJ m–2 y–1 and its gross production is 5 × l02 kJ m–2 y–1. The total energy passed on to primary consumers is 50 kJ m–2 y–1. Only 10 % of this energy is passed on to the secondary consumers.”

Deduce• Reach a conclusion from the information given• Example: Deduce the trophic level of Tuna in

the given food web

Plankton

Herring

Shrimp

Shark

Tuna

Marlin

Derive

• Manipulate a mathematical relationship to give a new equation or relationship

Design

• Produce a plan, simulation or model

Determine

• Find the only possible answer• In a species of plant, tall is dominant to short and

the production of round seeds is dominant to that of wrinkled seeds. The alleles are unlinked.

• A plant heterozygous for both characteristics is crossed with a plant homozygous for tall with wrinkled seeds.

• Determine the phenotypes and genotypes of the offspring of this cross.

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

• Example: Discuss the ethical implications of IVF• chance for infertile couples to have children; • genetic screening of embryos could decrease suffering from genetic

diseases; • spare embryos can safely be stored for future pregnancies/used for

stem cell research; • IVF is expensive and might not be equally accessible; • success rate is low therefore it is stressful for the couple; • it is not natural/cultural/religious objections; • could lead to eugenics/gender choice; • could lead to (unwanted) multiple pregnancies with associated risks.

Evaluate• Assess the implications and limitations

Example:

“Evaluate the evidence for global warming, using figures A and B (2).”

Biology Specimen Paper, 2009

Do not just describe, use evaluative language. Think of the reliability and limitations the given data have to arrive at a conclusion.

Explain

• Give a detailed account of the causes, reasons or mechanisms

• Using an example you have studied, explain a cross between two linked genes, including the way in which recombinants are produced.

Predict• Give an expected result• A farmer has rabbits with two particular traits, each

controlled by a separate gene. Coat colour brown is completely dominant to white. Tailed is completely dominant to tail-less. A brown, tailed male rabbit that is heterozygous at both loci is crossed with a white, tail-less female rabbit. A large number of offspring is produced with only two phenotypes: brown and tailed, white and tail-less, and the two types are in equal numbers.

• Predict the genotypic and phenotypic ratios of the F2 generation. Show your working.

Show• Give the steps in a calculation or derivation

Example:

“A male and female with normal colour vision each have a father who is colour blind. They are planning to have children. Predict, showing your working, the possible phenotypes and genotypes of male and female children.”

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Always show your working in ‘calculate’ and ‘determine’ questions!

Sketch• Represent by means of a graph showing a line

and labelled but unscaled axes with important features clearly indicated.

Example:“Sketch a graph to predict the effect of manipulating pH on the activity of an enzyme which has an optimal pH of 7.”

Enzyme activity

pH

Optimum pH

denatured

6 7 8

Suggest• Propose a hypothesis or other possible answer

Example:

“Suggest one reason in each case for the change in quantity of fish captured in the Atlantic and Indian Oceans from 1980 to 1990.” QuestionBank CD Rom