Figure 7 shows the world human population from 1800 to 2015 - Edexcel - GCSE Biology - Question 4 - 2020 - Paper 1

To test for proteins in a laboratory, the following steps should be taken:

1. Add Biuret reagent, which contains sodium hydroxide and copper sulfate, to the sample being tested.
2. If protein is present, there will be a color change from blue to mauve or purple.

To find the rate of increase from 2000 to 2010 using Figure 8, take the difference in mass of meat eaten:

• In 2000, the mass was 225 million tonnes.
• In 2010, the mass was 275 million tonnes.

The increase is:

$275 - 225 = 50 ext{ million tonnes}$

The time period is 10 years, so the rate of increase per year is

rac{50 ext{ million tonnes}}{10 ext{ years}} = 5 ext{ million tonnes per year}.

The area labelled cattle is smaller than the area labelled plants for several reasons:

1. There is less energy available in the cattle than in the plants that form the base of the pyramid.
2. Not all energy from the plants is converted into meat, as some is lost through metabolic processes.
3. Only a fraction of the plant matter consumed by cattle is digested effectively, further reducing energy availability.

A large increase in the mass of meat eaten can affect food security in several ways:

1. There will be less food available for people to eat directly, as significant amounts of grain and land are utilized for livestock feed.
2. Meat production does not yield as much food per acre as arable farming, making it less efficient in terms of food production.
3. More land will be necessary for animal farming, which can lead to less arable land available for crops grown for human consumption, potentially exacerbating food shortages.