Memdelian Inheritance - Inheritance which is obeying Mendel's laws.

Mendelism - The theory postulating that inheritable characteristics are governed by discrete factors in organism (particulate inheritance) and transmission of characteristics to offspring takes place according to regular and predictable ways. as given by Mendel's laws.

Mandel's Laws of Inheritance - (1) The Law of Segregation that the gametes produced by a hybrid or heterozygote contain unchanged, either one or the other of any two factors determining alternative unit characters in respect of which its parental gametes differed.
(2) The Law of Recombination-that the factors determining different unit characters are recombined at random in the gametes of an individual heterozygous in respect of these factors.

Mericarp - Said of any of the one seeded portions which are separated when a compound fruit undergoes division at maturity. Mericarps may be dehiscent or indehiscent.

Meristele - Anyone of a number of amphicribal vascualr portions which constitute a dictyostele.

Meristem - Said of a region consisting of actively dividing cells or the cells that have the potential of active division and including initials and their immediate undifferentiated derives.

Meristem Culture (shoot tip culture). Used for describing the culture of excised meristems on suitable nutrient media under aseptic conditions. Often gibberellic acid is added to the medium to promote normal growth of plantlet. Technique is often used for rapid propagation of plantlets, propagation of infertile plants nursery stock or F1 hybrids that do not breed true. Because most of the viruses do not infect plant apex, this technique is used to produce virus-free stock.

Mesarch - Said of describing maturation of xylem in which older proteozylem cells come in the centre of xylem strand due to both centripetal and centrifugal maturation of n ewer metaxylem cells.

Mesarch Succession - Said of the succession that occurs in a bare area with mesic condition and results in the development of mesosere which takes part in the stabilization of the area.

Mesic - Said of environmental conditions of a habitant in which water is present in normal amounts for plants and hence the plants in areas are mesophytes of all types.

Mesocarp - Said of the middle layer of the pericarp in an angiospermic fruit, which is situated between exocarp and endocarp. In many types of fruits such as peach, mango etc., mesocarp is fleshy, edible part of the fruit. In some fruits, mesocarp may be absent.

Mesogamy - Describing the type of fertilization in which pollen tube enters ovules and raches nucellus through sides of ovules (neither from micropylar nor from chalazal end) and then enters embryo sac.

Mesogenous - Said of an angiosperm stomatal complex in which subsidiary cells and guard cells are derived from same initial.

Mesophilic - Said of organisms that require moderate temperatures i.e., 30-40°C for their growth.

Mesophyl - Said of the parenchyma of a leaf which is differentiated into the cylindrical palisade cells with a large number of chloroplasts and arranged with the long axis at right-angles to the epidermis and the spongy mesophyll of loosely packed cells with fewer chloroplasts, and large air-spaces.

Mesophyte - A plant found in places where the water-supply is neither very scanty nor abundant.

Mesophytic Environment An environment in which the water supply is neither very scanty nor abundant.

Mesosere - Refers to the set of communities that are formed during mesarch succession in a mesic environment and that take part in stabilisation of the area thereby finally resulting in the establishment of climax in the area.

Mesosome - The structure occurring in bacterial cells by intrusion of plasma membrane into the protoplasm of the cell. Respiratory enzymes are associated with mesosome and it carries out the same function in bacterial cell as the mitochondrion in cukaryotic cells. It is also attached to DNAP and controls separation of replicated DNAP molecules in cell fission.

Mesozoic - Refers to an era of geological time between about 225 and 65 million years ago. It has been subdivided into Triassic, Jurassic and Cretaceous periods. The period was mainly dominated by seed ferns, cycads, ginkgos, conifers in plants and by reptiles in animals. .

Messenger RNAP (m RNA) - Refers to a linear single, stranded polynucleotide of uridine, adenine, guanidine and cytidine monophosphates. It is synthesized on DNA by mRNAP polymerase and sequence of bases in mRNAP has been found to be complementary copy of the base sequence in one strand of DNA. This DNA strand is known as sense strand.

Mestom Sheath (mestome sheath). Refers to a thin-walled type of bundle sheath present around a vascular bundle. It is found in some grasses.

Metabolic Inhibitor - A substance closely related chemically to the normal metabolite.

Metabolic Nucleus - A nucleus when it is not dividing, and when the chromatin is in the form of a net-work.

Metabolism - The net result of the biochemical processes of a living organism, or cells. The balance between anabolism and catabolism.

Metabolite - A substance used during metabolism, e.g., oxygen during respiration, or carbon dioxide during photosynthesis.

Metacentric - Refers to a chromosome in which chromatid arms on both sides of centromere are having equal lengths so that centromere appears to be situated in teh centre of the chromosome.

Metamitosis Mitosis in which the nuclear membrane disappears and the karyokinetic figure lies free in the cytoplasm.

Metamorphosis. A change in form or structure, during the development of an individual or species etc.

Metaphase - A stage in mitosis or meiosis when the chromosomes get arranged on equator of the spindle.

Metaphloem - Completely developed primary phloem, which consists of sieve-tubes and parenchyma.

Metaplasm - Any substance within the body of a cell which is not protoplasm, especially food material.

Metasyndesis - End-to-end union of the elements of a pair of chromosomes.

Metaxylem - Primary xylem derived from the procambium. The cells are heavily lignified, and have reticulate thickening or pitted walls, in consequence, they cannot be stretched.

Micellar Region - An area of crystallinity in a cellulose molecule.

Microbody - A small organelle in cytoplasm which is about 0.5 9μm in diameter and surrounded by a single membrane, having oxidative enymes. See glyoxysome, peroxisome.

Microfibril - A fine thread of cellulose in a cellulose cell-wall.

Microflora - The microscopic plants, e.g., fungi and bacteria of an organ or area.

Micronutrient (trace element). Refers to any of the elements that are needed by a plant in very small quanties for successful normal growth. Examples of micronutrients are heavy metals like copper, zinc, molybdenum, manganese cobalt etc. Boron, sodium, chlorine, vanadium, silicon ae also micronutrients.

Microphyllous - (1) Said of leaves, which are small, with a single central vein, especially of the Pteridophyta.
(2) Said of leaves of xerophytic plants.

Micropyle - (1) A canal into the nucellus which is formed by an upgrowth of the integuments(s). It remains as a minute pore in the testa of the Seed through which water passes prior to germination.