Command terms in IB Biology
All 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!
http://xmltwo.ibo.org/publications/migrated/productionapp2.ibo.org/publication/7/part/1/chapter/7.html
Objective 1
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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
A
D
C
B
H
F
library.kiwix.org
G
E
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
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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
Annotate
Add 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
Progesterone
Maintains
endometrium
Inhibits FSH and LH
FSH and LH peak
causing ovulation
Oestrogen
thickens
endometrium
FSH and LH
stimulate
development of
oocyte
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
Reproduce by means of spores
• 2. Seeds are made in cones
Seeds are made in fruits
• 3.Spores are made in capsule
Spores are made under leaves
go to 2
go to 3
A
B
C
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!
Describe
Give 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
“Identify the response time of
group 2 on day 31 of the
study.”
“Identify the group with
the largest difference in
response time from day 2
to day 31.”
Response time (secs)
Example:
May2009TZ1SLP3
Pick one single answer
‘Identify’ can be used for part of diagram or
graph
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
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•
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
Analyse
Interpret data to reach conclusions
Example: “Analyse the results of this experiment.”
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Read the data thoroughly and underline the important words
Use the data to reach the conclusion
Pay attention to marks available
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
Shark
Marlin
Plankton
Tuna
Shrimp
Herring
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.”
Always show your working in ‘calculate’ and
‘determine’ questions!
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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.”
Optimum pH
Enzyme activity
denatured
6
7
8
pH
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.”
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