It seems you are looking for an informative text explaining the concept of — likely a homework assignment or assessment in Life and Earth Sciences for the final year of the D series (Mathematics-focused track) in Francophone African school systems (e.g., Cameroon, Côte d’Ivoire, Senegal, DRC).
Below is a clear, structured informative text on the subject. In the Francophone education systems of many African countries, the Terminale D class is a specialized track focusing on mathematics and sciences, with a strong emphasis on Life and Earth Sciences (SVT – Sciences de la Vie et de la Terre). A "Devoir" refers to a formal, graded assessment — often a homework assignment, a test, or a practice exam. devoir de svt terminale d pdf