Worksheet 10.2
Command term to master
Distinguish
Give the differences between named items.
Example
Assessment statement 10.2.2
Distinguish between autosomes and sex chromosomes.
Author’s comment
Students often miss out on getting full marks on questions which involve the command term
distinguish (and the command term compare) because they tend to describe each item rather than
answer the question.
You must know that the command term distinguish asks only for the differences between items
(whereas the command term compare asks you to give both the similarities and differences). Secondly,
for each difference (or similarity), it is important that each sentence in your answer refers to both of the
named items.
For example, if item A is being distinguished from item B, you should write sentences along the lines
of: A is _______ whereas B is _______. Other useful generic sentence structures include: A is
bigger/smaller than B. A has a higher/lower value than B. A is more/less likely to happen than B.
Many students write A is _______. and then another sentence saying B is _______. Such a structure is
more compatible with the command term describe rather than distinguish (or compare).
Example answer
To answer a question on assessment statement 10.2.2, you should include sentences such as the
following.
•
•
•
The sex chromosomes are the 23rd pair of chromosomes, the X and Y chromosomes, whereas the
autosomes are the other 22 pairs of chromosomes.
Autosomes always come in pairs of homologous chromosomes that are the same size and shape
whereas the sex chromosomes can be either XX or XY.
Traits such as colour blindness, whose alleles are carried on the sex chromosomes (sex-linked
traits) tend to show up more in one sex than the other whereas traits whose alleles are carried on
the autosomes (autosomal traits) usually show no difference in frequency between males and
females.
© Pearson Education Ltd 2010. For more information about the Pearson Baccalaureate series please visit www.pearsonbacc.com 1
Are tables useful?
Sometimes the IB accepts a distinguish (or compare) answer in the form of a table like this one.
Aspect to distinguish
(or compare)
Autosomes
Sex chromosomes
Which chromosomes
chromosomes 1 to 22
only 23rd pair
Size and shape of homologues
identical for both
identical when XX but different
when XY
Frequency of traits whose locus
is found there
no difference between males and
females
often show up more frequently in
one sex than the other
However, this format is probably better suited to a short answer question than an essay question. For an
essay question, a table like this could be used as a rough draft when preparing your answer but you
should write out your actual answer in prose, making each row of the table into a sentence.
© Pearson Education Ltd 2010. For more information about the Pearson Baccalaureate series please visit www.pearsonbacc.com 2