Haemoglobin is a protein carried in red blood cells. Fig. 10.1 shows three kinds of change that can occur in a gene. Table 10.1 shows one triplet of the hae...

Yoghurt is made by adding a culture of Lactobacillus bacteria to warm milk and keeping the mixture at a suitable temperature. As the bacteria feed on the mil...

A runner took part in a 400 m race. During the race her leg muscles could not be supplied with enough oxygen, so they respired anaerobically to keep releasin...

A species of land snail has two forms of shell, a banded form and a plain form. The snails are eaten by thrushes, which are birds that hunt the snails by sig...

Variation means the differences that exist between individuals of the same species. A student investigated one example of variation in plants. Walking along ...

The male gamete and the female gamete are both specialised sex cells, but they differ greatly in their size and in their structure because they are adapted f...

When roads, farms and towns are built across a large continuous forest, the forest is broken into smaller patches separated from one another. This breaking u...

Iron is a mineral that the body needs in only small amounts each day in order to stay healthy. Fig 3.1 is a bar chart that compares the mass of iron actually...

A small, isolated island has a large population of rabbits that feed on the grass growing there. Because the number of rabbits has been rising quickly, a few...