Date | May 2019 | Marks available | 1 | Reference code | 19M.1.SL.TZ1.3 |
Level | Standard level | Paper | Paper 1 | Time zone | Time zone 1 |
Command term | Deduce | Question number | 3 | Adapted from | N/A |
Question
The images show a sequence of changes in an organism.
[Source: Copyright (2007) National Academy of Sciences, U.S.A. 'A comparative analysis of frog early development'.
Eugenia M. del Pino, Michael Venegas-Ferrín, Andrés Romero-Carvajal, Paola Montenegro-Larrea, Natalia
Sáenz-Ponce, Iván M. Moya, Ingrid Alarcón, Norihiro Sudou, Shinji Yamamoto, and Masanori Taira,
PNAS July 17, 2007 104 (29) 11882–11888; https://doi.org/10.1073/pnas.0705092104]
What is the change and which process is necessary for it to occur?
Markscheme
B
Examiners report
This question was also criticised by some teachers, because the programme does not specify that students should view microscope images of embryos. A principal aim in IB Biology exams is to test whether candidates can apply their knowledge and understanding in a wide range of contexts. There was no expectation that images of embryos had already been seen. This question had the highest percentage of candidate answering correctly and the lowest discrimination index of any in the exam. We can be pleased that there was widespread understanding that embryo development was shown and that it involves cell differentiation. However, because so many candidates got the question right, it did not help much in determining which the strongest candidates were. To do that a success rate of a half to two thirds is better.