Answer: Leeuwenhoek biggest contribution is to the first tenet of the cell theory.
Explanation: the first tenet of cell theory states that every living being is made of cells and even an organism can be made of just one cell able to reproduce by itself.
Leeuwenhoek observations stablish the existence of microscopic structures alive some with movement. This helped other scientists to determinate this structures were cells that can make vital processes such as feeding, breathing or reproducing which are determinant in biological definition of life.
Answer and Explanation:
1. Amino-acid sequence is the primary structure of a protein
2. Alpha helices, beta sheets and coiled coils refers to the protein folding and they represent the secondary structure of a protein
3. Protein ensemble formed by alpha helices, beta sheets and coiled coils represent the tertiary structure of a protein
4. Macromolecules with multiple polypeptides form globular or fibrous protein structures (quaternary structure)
Overexploitation, Habitat loss, invasive species, climate change
I think the correct answer from the choices listed above is option A. The anatomical adaptation which helps an elephant regulate its body temperature are its large ears increase surface area so that more heat is lost by radiation. Heat can be released as they flap these ears. So there is your correct answer