| Date | November 2010 | Marks available | 1 | Reference code | 10N.3.SL.TZ0.20 |
| Level | Standard level | Paper | Paper 3 | Time zone | TZ0 |
| Command term | Calculate | Question number | 20 | Adapted from | N/A |
Question
Many factors affect the distribution of animal species including weather patterns. The mosquito Anopheles is a carrier of malaria, a disease that kills one to two million people annually. The eggs of the mosquito are laid in water and they hatch out as larvae before turning into adult mosquitoes. A study was undertaken to look at the influence of weather patterns on the incidence of bites on children. Being bitten increases the risk of catching malaria.
The graphs show human biting rates (HBR) by Anopheles gambiae and Anopheles funestus and precipitation over the study period.
Calculate the difference in peak HBR for A. gambiae and A. funestus for week 6.
Suggest how predictions of global climate changes, such as predictions of precipitation patterns, could be used to help control malaria.
Suggest another factor which might affect the ecological distribution of mosquitoes.
Markscheme
35 (accept answers in the range of 34 to 37)
a. spraying insecticides just before rainy seasons;
b. draining swamps before (and after) rain;
c. providing (endangered) population with repellents/mosquito nets before rainy season;
temperature / breeding site / food supply / predators / other reasonable answer
Do not accept global warming.
Examiners report
The majority were able to correctly do the calculation.
There were many vague answers to this section which did little more than repeat the question without giving a specific reply. A specific action was required such as use of mosquito nets or spraying insecticides rather than stating that “protection is needed”.
Most were able to give a factor that could affect mosquito distribution.
