The passage outlines one method of estimating the size of an animal population. Complete the passage by using the most appropriate scientific terms. The size of a population of animals can be estimated using the mark-release-recapture method. A sample of animals is captured using a humane (harmless) trap and is counted. The animals are marked using a method that does not harm them. This can be done using a small tag or . The marked animals are released into the area where they were captured. Time is allowed for the marked animals to mix into the population. This period of time must be short so that emigration, immigration, migration or do not occur. A second sample of animals is then captured and the number of marked and unmarked animals is counted. The population size can be estimated using the Index. For reliability, the method should be .

1. (a)The passage outlines one method of estimating the size of an animal population. Complete the passage by using the most appropriate scientific terms. The size of a population of animals can be estimated using the mark-release-recapture method. A sample of animals is captured using a humane (harmless) trap and is counted. The animals are marked using a method that does not harm them. This can be done using a small tag or . The marked animals are released into the area where they were captured. Time is allowed for the marked animals to mix into the population. This period of time must be short so that emigration, immigration, migration or do not occur. A second sample of animals is then captured and the number of marked and unmarked animals is counted. The population size can be estimated using the Index. For reliability, the method should be .[4]
2. (b)Himalayan balsam, Impatiens glandulifera, is an annual plant native to Pakistan, India and Nepal. It was first introduced into the United Kingdom (UK) in 1839 because of its attractive flowers. Individual plants can produce thousands of mature seeds. These can be dispersed for long distances when the capsules that contain the seeds burst. Fig. 10.1 shows Himalayan balsam growing in a woodland. [Figure 10.1] Himalayan balsam has now become established in the UK. It is listed as an invasive alien species and attempts are being made to eradicate (remove) the plant. Not all alien plant species are considered to be invasive. Suggest why Himalayan balsam has been listed as an invasive alien species in the UK.[4]

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