How do birds have a genetic variation

Babies with very low or very high weight are less likely to survive .

Astructure that is found in a plant cell and not in an animal cell is a ? central vacuole mitochondrion nucleus ribosome

This question is only for applicants to scholars for medicine or scholars for dental medicine: what aspects about medicine (or dental medicine) intrigue you? describe how these aspects influence your life. (100-650 words)