1. Alleles - different forms a gen may have for a trait.
2. Allulvial fan - triangular deposit of sediments that is formed when a river empties from a mountain valley out onto a flat, open plain.
3. Atherosclerosis - cardiovascular condition resulting from fatty deposits on aterial walls, which can clog blood vessesl and interfere with blood flow.
4. Antigens - proteins and chemicals that are foreign to the body.
5. batholiths - largest intrusive ignesous rock bodies that form when magma cools underground before reaching Earth's surface.