Question 19M.1A.SL.TZ1.2
| Date | May 2019 | Marks available | [Maximum mark: 1] | Reference code | 19M.1A.SL.TZ1.2 |
| Level | SL | Paper | 1A | Time zone | TZ1 |
| Command term | Compare | Question number | 2 | Adapted from | N/A |
The image shows an electron micrograph of part of a cell.
[Source: Dr. Eldon Newcomb – Emeritis Professor at The University of Wisconsin – Madison.]
Which features do the two structures labelled X and Y have in common?
A. They are surrounded by a double membrane.
B. They contain 70S ribosomes.
C. They contain naked DNA.
D. They are only found in leaf cells.
[1]
A
There was criticism that the resolution of the micrograph wasn’t high enough, but it was typical for electron micrographs of plant cells and the internal structure of chloroplasts and the nucleus was clear. This skill from 1.2 of the Core was being tested: Interpretation of electron micrographs to identify organelles and deduce the function of specialized cells. The nucleus and chloroplasts both had a typical appearance, so well-prepared candidates should have been able to identify them. Answer A could then be chosen either by eliminating the incorrect answers, or by knowing that both nucleus and chloroplast are double membraned. The endosymbiotic theory for the origin of chloroplasts should have helped inform candidates about the two membranes of chloroplasts.
