Charles Darwin proposed the theory of natural selection - AQA - GCSE Biology - Question 1 - 2018 - Paper 1

The fossil in Figure 1 may have formed if the snake was covered in sediment or mud after its death. Over time, the soft parts of the snake would decay or be eaten, while the bones or hard parts might not decompose. Eventually, minerals could replace the bones, leading to the formation of a fossil.

The Japanese rat snake and the Texas rat snake evolved due to their adaptation to different environments. The Japanese rat snake, which primarily inhabits grassy areas, has a green color that provides camouflage and helps it avoid predators. In contrast, the Texas rat snake, found in dry and dusty environments, has a different coloration suited for its habitat. The color adaptation is facilitated by genetic variations—mutations in different alleles that were advantageous for survival in their respective environments.

A species might become extinct due to changes to the environment, which could include habitat destruction, climate change, or the introduction of new predators that outcompete the native species.