Figure 24 shows the world human population from 1800 to 2015 - Edexcel - GCSE Biology - Question 10 - 2020 - Paper 1

To test for protein, one can use the Biuret test. Follow these steps:

1. Add a few drops of Biuret reagent (which contains sodium hydroxide and copper sulfate) to the sample.
2. If protein is present, the solution will change color from blue to mauve or purple.

From examining the graph in Figure 25, the mass of meat consumed in 2000 was approximately 225 million tonnes and in 2010 it was about 300 million tonnes. To find the rate of increase:

Increase = 300 million tonnes - 225 million tonnes = 75 million tonnes.

The rate of increase is:

$\text{Rate} = \frac{75 \text{ million tonnes}}{10 \text{ years}} = 7.5 \text{ million tonnes per year}$

The area labelled cattle is smaller than that labelled plants because of energy transfer in food webs. Only a fraction of energy is passed from one trophic level to the next, typically about 10%. This means that much more plant biomass is required to support the smaller biomass of cattle. Therefore, the energy pyramid reflects that less energy and biomass are available at higher trophic levels.

A significant increase in meat consumption can strain food security in several ways. Firstly, the resources (land, water, and feed) required for meat production are substantial, and diverting these from crop production could reduce the availability of essential food grains. Secondly, high meat consumption can lead to environmental degradation, exacerbating issues such as climate change that threaten food production systems. Lastly, increased demand for meat may lead to higher prices for food staples, making it difficult for lower-income populations to access sufficient nutritious food.