F
F 1 (first filial generation)
The first filial or hybrid offspring in a genetic cross-fertilization.
F 2 (second filial generation)
Offspring resulting from interbreeding of the hybrid F 1 generation.
F factor
A fertility factor in bacteria, a DNA segment that confers the ability to form pili for
conjugation and associated functions required for the transfer of DNA from donor to
recipient. May exist as a plasmid or integrated into the bacterial chromosome.
Fascia
A sheet or band of fibrous connective tissue separating or binding together muscles and
organs etc
Facilitated diffusion
The spontaneous passage of molecules and ions, bound to specific carrier proteins, across a
biological membrane down their concentration gradients.
Facultative anaerobe
An organism that makes ATP by aerobic respiration if oxygen is present but that switches to
fermentation under anaerobic conditions.
Fascicular cambium
Fascicular cambium (plant anatomy), ...vascular bundle develops a meristematic area of
growth from an undifferentiated (parenchymatous) layer of cells between the primary
xylem and primary phloem, called a fascicular cambium.
Fascicular vascular cambium
Cambium that develops within the vascular bundle.
FAD
Abbreviation of flavin adenine dinucleotide, a coenzyme that functions as an electron
acceptor in the Krebs cycle.
Fallopian tube
Either of a pair of slender ducts through which ova pass from the ovaries to the uterus in the
female reproductive system of humans and higher mammals.