OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What is considered when calculating the best estimate of species distribution along a transect?

1. The number of quadrats used and species counted

2. Only the largest organisms observed

3. The average temperature during the study

4. The presence of human activity in the area

The correct answer is: The number of quadrats used and species counted

When calculating the best estimate of species distribution along a transect, it is essential to consider the number of quadrats used and the species counted. The use of quadrats allows researchers to systematically sample and quantify the number of different species present in specific areas of the transect. By counting the species within these quadrats, ecologists can gain a more accurate representation of how species are distributed across the different habitats along the transect. This statistical approach ensures that the estimate of species distribution is based on a reliable sample, leading to conclusions that better reflect the actual biodiversity of the area. Counting only the largest organisms observed does not provide a complete picture of species diversity, as many small species may be overlooked. Temperature may influence species distribution but is not sufficient alone to estimate distribution without direct observational data. Similarly, while human activity can affect local ecosystems, it does not directly relate to calculating species distribution, which focuses on the organisms present in the sample area.