biology-dictionary_11-06-2009

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Mendel's second law
The principle, originated by Gregor Mendel, stating that when two or more characteristics
are inherited, individual hereditary factors assort independently during gamete production,
giving different traits an equal opportunity of occurring together.
Meniscus
The curved top surface of a column of liquid.
Menstrual cycle
A type of reproductive cycle in higher female primates, in which the nonpregnant
endometrium is shed as a bloody discharge through the cervix into the vagina.
Meristem
Plant tissue that remains embryonic as long as the plant lives, allowing for indeterminate
growth.
Meristematic cells
A meristem is a tissue in all plants consisting of undifferentiated cells (meristematic cells)
and found in zones of the plant where growth can take place.
Meroblastic cleavage
A type of cleavage in which there is incomplete division of yolk-rich egg, characteristic of
avian development.
Mesentery
A membrane that suspends many of the organs of vertebrates inside fluid-filled body
cavities.
Mesocarp
The middle, usually fleshy layer of a fruit wall.
Mesoderm
The middle primary germ layer of an early embryo that develops into the notochord, the
lining of the coelom, muscles, skeleton, gonads, kidneys, and most of the circulatory system.
Mesoglea
The layer of gelatinous material that separates the inner and outer cell layers of a
coelenterate
Mesophyll
The ground tissue of a leaf, sandwiched between the upper and lower epidermis and
specialized for

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