Extracting aluminum from bauxite ore requires 20 times more energy than extracting it from aluminum from recycled sources so therefore that is a good reason to promote its recycling starting with pop and beer cans which are things that most of us use.
Answer:
B.
Explanation:
B. is the best choice here because it is the only characteristic listed that only describes a eukaryotic cell. Both prokaryotic and eukaryotic cells have cell membranes, cytoplasm, and cillia. However, only eukaryotic cells have a nucleus to store their DNA.
Answer:
Sperm-egg interaction
Explanation:
The formation of fertilization envelope is well-studied on the model system- sea urchin. It has been shown that, the fertilization envelope is formed after the initial sperm-egg interaction from the egg surface vitelline envelope and the paracrystalline protein fraction which is derived from cortical granules. Secretion from cortical granules, prevents polyspermy.
No system is closed off by it surroundings.
