Dorsal-ventral patterning within the ectoderm of the Drosophila embryo requires seven zygotic genes including sog (short gastrulation). Sog is expressed in the ventrolateral region of the embryo that gives rise to the nerve cord.
n. 1  1. The science of life and of living organisms, including their structure, function, growth, origin, evolution, and distribution. It includes botany and zoology and all their subdivisions. 2  2. The life processes or characteristic phenomena of a group or category of living organisms: the biology of fungi.
Physiology definition, the branch of biology dealing with the functions and activities of living organisms and their parts, including all physical and chemical processes. See more. Dictionary.com