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Home >> Botany Dictionary >> Chemosynthesis - Cladogenesis
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Chemosynthesis - The formation of organic material by some bacteria by using energy by complex chemical reactions as in respiration.
Chemotaxis - Used for a tactic movement which takes place.in response to a chemical stimulus. Bacteria commonly exhibit positive chemotaxis i.e., swim towards regions of higher concentrations of food materials such as peptone and lactose. Negative chemotaxis may be occurring in response to the presence of toxic substances in the surroundings
Chemotaxonomy - Used for describing principles and practices of classifications of plants on the basis of results obtained by application of the, principles and procedures of chemical analysis.
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Chemotroph - An organism which obtains energy needed for the synthesis of organic molecules from oxidation of inorganic or organic compounds present in its environment without involving light energy in the process (as in chemoautotroph and chemoheterotrophs).
Chemotropism - A tropic movement which takes place in response to a chemical stimulus. For example, pollen tube growth through agar culture towards a piece of implanted pistil exhibits negative chemotropism in growing away from oxygen and positive chemotropism in growing towards chemicals excluding from the pisti
Chernozem(=Black Earth) - A grassland soil which is developed under fairly dry conditions so that there occurs little leaching. There is an accumulation of calcium carbonate at about 6 feet.
Chestnut Soil - A grassland soild which is developed under arid conditions. There occurs no leading, and it carriers shallowrooting vegetation. The calcium carbonate layer exists near the surface.
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Chiasma (pl). Chiasmata). The joint between two chromatids of two homologous chromosomes resulting in an interchange of chromatic material.
Chiasma Interference - Describing of the effect of the occurrence of a crossing over at a point in a pair of chromatids on the chances of second crossing over in the same pair of chromatids. It normally means the reduction of chances of second cross over (positive chiasma interference). Negative chiasma interference, where there occurs an increase in chances of a second cross over, is rarer.
Cauline - (1) Growing from the stem, in contrast to growing from the base of the plant.
(2) Appertaining to the stem.
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Chimaera - A plant which is having tissues of more than one genetic type. It occurs as a result of the mutation or abnormal distribution of chromosomes in one cell early in development thereby affecting tissues devised from it. It can be produced by grafting different types of plants - a graft hybrid.
Chiropterophilous. Pollinated by bats.
Chi-Squared - Describing the ratio of an observed sum of squares to the appropriate or corresponding variance as fixed by a hypothesis.
Chlamydospore - A thick-walled sexual spore which is able to survive adverse conditions.
Chlamydozoa - An obsolete phylum which is used to include the viruses.
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Chi-Squared Test (X2 test) - A test which is commonly used for studying level of correspondence between observed and expected frequencies in an experiment. It is especially used when observations fall into discrete classes. Value of X2 is found by calculating the (observed frequency-expected frequency)2 expected frequency for each class of observations and then adding these together. Sum obtained is then checked in a table of X2 values for different degrees of freedom at various probability levels.
Chloranthy - Describing an abnormal flower in which all the parts have developed as leafy structures.
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Chlorenchyma - Describing tissue of parenchymatous cells having numerous chloroplasts in the cells, and often large intercellular spaces.
Chlorin - A derivative obtained from chlorophyll when it loses the magnesium, phytol and methyl alcohol, and the 5-carbon ring is open.
Chloropholyllase - An enzyme which occurs in association with chlorophyll and is able to hydrolyse the phytol group in the chlorophyll, and hence decompose it.
Chlorophyllins - The two acid precursors of chlorophyl a and chlorophyll-b respectively.
Chlorophyta - A division of the Algae in which chlorophyll is the photosynthetic pigment, and most of them accumulate starch.
Chloroplast - A variously shaped plastid which is made up of lamellated grana having chlorophyll distributed on them. The grana get interspersed in the non Iamellate stroma. They get embedded in the cytoplasm.
Chlorosis - An abnormal yellowing of leaves with occurs due to the chlorophyll content below the normal. It is caused by a deficiency of certain elements, e.g., iron or magnestium, attack by parasites e.g., virus yellows, lack of light, drought etc.
Chlorostatolith - A chloroplast having starch, and acting as a statolith.
Chromatid - A half chromosome formed during duplication in early prophaseand metaphase of mitosis and between diplotene and the second metaphase of meiosis. After these stages it is termed as a daughter chromosome.
Chromatin - A nucleoprotein forming part of chromosomes. It is made up of two proteins, one of which is histone, and DNA and RNA.
Chromatin Loop - Describing the region of relatively unwounded DNA, about 200 nm in length and extending outwards in a loop from the chromosome. Transcription can take place only in such an uncoiled condition of DNAP. These may correspond to genes actively involved in protein synthesis.
Chromatography - A technique used for the separation and identification of components of a mixture of compounds. This mixture is dissolved in the some liquid or gas solvent (mobile phase) when solution is allowed to pass through another solid, liquid or gas medium (stationary phase). Separation of component substances takes place due to their relative absorption in stationary phase.
Chromatophore - Used for a pigmented lamellar or vesicular structure isolated from disrupted photosynthetic bacteria or blue-green algae.
Chromomere - A particulate portion of chromosome becoming apparent when condensation and contraction of chromatin taken place in meiosis.
Chromoneme - (1) The genetic material of bacterium.
(2) The thread-like structures which are running paralell along the length of a chromosome and seen in certain stages of nuclear division. (pI. chromonemata)
Chromoplast - A plastid, having one or more pigments including chloroplasts.
Chromosome - One of the deeply staining rod-like structures in the cell-nucleus carrying the genes, and having DNA. There is a constant number for any particular species. They undergo a . co-ordinated cycle of reproduction during mitosis and meiosis.
Chromosome Aberration - See chromosome mutation.
Chromosome Arm - One of the two parts of a chromosome to which the spindle fibre has been attached along the side.
Chromosome Complement - The set of chromosomes characteristic of a cell of a species.
Chromosome Cycle - , The complete changes in the chromosome taking place during the life-cycle.
Chromosome Map - A diagram of a chromosome which shows the position of the genes and is obtained by a statistical analysis of the frequency of crossing-over.
Chromosome Mutation - Describing an alteration in member order or arrangement or genes which is caused by structural changes in a chromosome. Sometimes it may in-. volve a large number of genes and aberration may be microscopically visible.
Chromosome Number - The total number of chromosomes possessed by a species which is definite for each species, given by haploid number (n) or diploid number (2n).
Chromosome Puff - A swollen region of a polygene chromosome which corresponds to a site where transcription (messenger RNA synthesis) is actively taking place. .
Chronistics - Used for the study of time taken for evolutionary events to occur.
Cilliary Body - A basal body in the cell at the basal end of a cilium. See kinetosome, flagellum.
Ciliate - Describing a structure which gets fringed with fine hairs.
Cincinnus - A monochasium having successive braches borne on opposite sides of the stem.
Circadian Rhythm (diurnal rhythum) - Describing the regular occurrence of a phenomenon en 24-hurly intervals. For example, me plants exhibit a characteristic change in leaf position on a daily cycle.
Circinate Vernation - Describing the vernation in which leaf primordium is rolled in on itself from its apical to basal end, towards the adaxial surface so that the apex lies in the middle of the coil. It occurs in most of the ferns (except Ophioglessales), in certain cycads and extinct seed ferns.
Circumnutation (Nutation) - The rotation of the tip of a growing stem so that it traces a helical curve in space.
Cis-Arrangement(Coupling) - Describing a situation in which an individual is heterozygous for two linked genes (either two units of a function or two mutations in same functional unit) and one chromosome is having both (or mutant) alleles.
Cisternae - Enclosed spaces in the endoplasm of a cell, which get separated. from the ground substance by the cytoplasmic membranes.
Cis- TransTesl. A test to find out whether mutations having similar effects are present in the same or different genes ( which are defined as units of functions).
Cistron - A gene defined as a unit of function i.e., a length of DNA which can code for a single protein polypeptide.
Citric Acid Cycle - Used for a process by which acetyl S, coenzyme A is broken down to carbon dioxide and water during cellular respiration. The process takes place on the mitochondria.
Cladistics - Used for a method of classification in which the relationships between organisms are represented by a diagram or cladogram based on selected shared characteristics.
Clad ode - Used for the modification of an internode of stem into a structure which is resembling and carrying out the functions of leaves and where leaves are highly reduced becoming functionless e.g., cladodes of Asparagus.
Cladogenesis - Used for the branching of a cladogra
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