| Date | November 2011 | Marks available | 3 | Reference code | 11N.3.SL.TZ0.8 |
| Level | Standard level | Paper | Paper 3 | Time zone | TZ0 |
| Command term | Explain | Question number | 8 | Adapted from | N/A |
Question
The following is an electron micrograph of a chloroplast.
Label I and II.
I. ..................................................................
II. ..................................................................
Explain the relationship between chloroplast structure and its function.
Distinguish between oxidation and reduction.
Markscheme
I. granum / grana
II. stroma
(both needed)
large surface area of grana/thylakoids for light absorption/electron transport chains;
(small) space inside thylakoids for accumulation of protons;
(fluid) stroma contains enzymes/chemicals for light-independent reactions;
presence of DNA/ribosomes means production of specific proteins possible;
different photosynthetic pigments absorb different wavelengths of light;
starch grains store excess carbohydrates from photosynthesis;
Responses do not need to be shown in a table format.
Examiners report
Many candidates could correctly label the two parts of the chloroplast indicated.
Many scored two of the three marks on relating chloroplast structure to function.
Candidates seemed to either have a clear understanding of oxidation and reduction with regards to loss and gain of oxygen, hydrogen and electrons, thus gaining the two marks, or to have no idea at all.
