~

~ -...

Biology extended essay

International Baccalaureate"
© International Baccalaureate Organization 2024
Baccalaureat lnterrliltlonilll International Baccalaureate® | Baccalauréat International® | Bachillerato Internacional®
Bach1llerato lnternacion•I
May 2024 subject report Biology extended essay

Contents

Grade boundaries 3
Extended essay 4

Page 2 / 6
© International Baccalaureate Organization 2024
May 2024 subject report Biology extended essay

Grade boundaries
For grade boundary information, please refer to the Grade boundaries for Diploma programme
coordinators document available on the PRC.

International Baccalaureate
Baccalaureat International
Page 3 / 6
© International Baccalaureate Organization 2024 Bachillerato Internacional
May 2024 subject report Biology extended essay

Extended essay
The range and suitability of the work submitted
There was a wide range of work submitted. A lot of original and creative proposals but some were too
ambitious. On the other hand, there were few simple or repetitive investigations not recommended for
the EE. Microbiology experiments and factors affecting germination and growth of seedlings, were the
most common.
The majority of essays were based on a suitably biological topic. Essays which were essentially literature-
from
sources resulted in poor performance. Most of the ambitious proposals used databases with very few data
or old data. Many bibliographic essays had students only describing results without clearly making their
own analyses.
Essays based on practical work carried out at the school or a university or other research institution, have
been more common in this session. In some cases the EE did not include the supervisor´s comment.
Students still have problems with statistical analysis: Excel allows it to be done very easily, but the correct
choice of tests, their justification and their interpretation depend on the knowledge of the student.
However, in some cases the supervisor may have influenced the choice of tests.

Student performance against each criterion

It seems that there is a better understanding of what is required in each criterion.
Criterion A
In general the RQ was not fully focused as the way to record the dependent variable was not included.
Very few cases did not state the RQ on the cover page and sometimes it was not stated in the form of a
question. The topics were generally well focused on the research question but in many cases they were
introduced in an ineffective way, without clarifying the biological or academic bases to answer the
research question. Many research questions were not falsifiable or verifiable. The sources consulted were
sufficient (in general) and contributed to the research focus of the essay. Some sources were not purely
scientific. It is observed that students are aware of the importance of the selection of appropriate sources
compared to previous sessions.
The method selected was appropriate to address the RQ but there were limitations that made the method
difficult to be reproduced and in many cases the variables were limited and not fully controlled. Often the
methodology was incomplete resulting in a non-replicable experiment. In other cases there was a lack of
standardisation and/or a lack of controls.
A common omission was the justification for the selection of the ranges of the independent variables in
experimental work and statistical tests chosen. In the bibliographic essays, the selection of the sources
used, the criteria used to select the quality ones, the how and why of the selection was not always
mentioned. Particularly in this category, it is essential to have a good number of scientific articles and/or
databases from recognized sites.

Criterion B
The selection of source material was mostly relevant and appropriate although superficial and limited in
many cases. The biological comprehension in general was limited by a superficial discussion with a partial
use of sources. Technical terms were not always explained and the use of biological terminology was
limited in general. The use of in-text citations has also been better understood. Sometimes only textbooks

Page 4 / 6
© International Baccalaureate Organization 2024
May 2024 subject report Biology extended essay

were consulted lowering the standard of the essay. There are still many students who do not use sources
in the discussion, without a clear relationship with the results obtained, thus lowering their level of
understanding.
Criterion C
The majority of the research was appropriate and its application was clearly relevant to the research
question. The analysis was in general adequate. Most students carried out appropriate statistical analysis
including normality tests, to know if they had to use a parametric or non-parametric statistical test. The
discussion and conclusion were in general not supported by sources or without a biological explanation.
In some cases, where the student pointed out unresolved issues, there were suggestions as to how these
might be further investigated.
Criterion D
In general the structure of the essay was adequate. In some cases the RQ, title of essay or name of the
subject were omitted. Some students omitted the word count. Some essays included important
information in tables or in the appendix to avoid overpassing the word count. Sometimes there were too
many graphs that could have been summarized in a single one. Some essays did not show the raw data
and others showed too many tables of raw data that could have been in the appendix.
Criterion E
Most reflections were descriptive and narrative, giving the student an account of the meetings with the
supervisor and the outcomes of these. Interim reflections were more analytical with the student solving
problems to carry out the method accurately. The viva voice in general reflected the benefits and
outcomes of the essay as a personal experience.

Recommendations for the supervision of future students

A supporting letter from an outside institution when the work for the essay is conducted at a university or
other institution must be included. There must be evidence that informed consent was obtained from
participants in a trial on human subjects.
Photographs to show the work was really performed can be included in the annex, but the source must
be included.
The supervisors should discuss with the students each one of the criteria that will be used to evaluate the
essays.
The student should clearly and precisely state the topic and the research question, evidencing the
variables (independent and dependent) in a well-focused manner. In addition, in the introduction, locate
the variables in a local and global context.
The number of individual minimum data in experimental tests and the justification for the selection of the
statistical test is necessary.
The supervisor should ensure that IB requirements regarding ethical standards and quality of referenced
information are met. Some students still use Wikipedia, Khan Academy, blogs, biology textbooks,
encyclopaedias, newspapers, instead of a majority of scientific journals.
There have been a few essays where body fluids of harmful bacteria have been used in their experiments.
The reflections (criterion E) is not only a description of their meetings but of the work itself, of the steps
and problems encountered and their solutions.

International Baccalaureate
Baccalaureat International
Page 5 / 6
© International Baccalaureate Organization 2024 Bachillerato Internacional
May 2024 subject report Biology extended essay

Students should use citations in the introduction, in the body, and in the discussion of the essay, to
demonstrate a better understanding of the biological processes involved.

Further comments
Most essays surpass the maximum number of words with lots of tabulated text. This affects presentation
(criterion D) and the examiner will only correct up to the limit allowed. This means that a very important
part of the essay, usually discussion and/or conclusion will be ignored, affecting criterion C.

International Baccalaureate
Baccalaureat International
Page 6 / 6
© International Baccalaureate Organization 2024 Bachillerato Internacional