| Date | May 2009 | Marks available | 1 | Reference code | 09M.1.HL.TZ2.20 |
| Level | Higher level | Paper | Paper 1 | Time zone | Time zone 2 |
| Command term | Question number | 20 | Adapted from | N/A |
Question
The following graph refers to questions 19 and 20. It shows variation in the concentration of CO2 in the atmosphere as measured at Mauna Loa in Hawai’i. The small inset graph shows the variations in CO2 during a one year period.
Why does the amount of CO2 fall between April and August?
A. Seasonal increase in the rate of photosynthesis in northern hemisphere forests
B. Seasonal decrease in the rate of photosynthesis in northern hemisphere forests
C. Seasonal decrease in the rate of fossil fuel consumption
D. Seasonal increase in the amount of CO2 taken up by the oceans
Markscheme
A
Examiners report
Assessment statement 5.2.2 says to analyze the changes in concentration of atmospheric carbon dioxide using historical records. This means candidates should have used the data provided, or data of a very similar nature. Most candidates found the questions easy. Although in question 20 other options might seem correct, answer A was the most correct.
