| Dependent variable | The factor or parameter in an experiment that is measured. The independent variable should alter the dependent variable. |
| Determinate | A type of growth in which organs grow until a certain size is reached |
| Dicot | One of the two large groups of flowering plants distinguished by the presence of of two seed leaves or cotyledons |
| Differentiation/ Differentiate | Process by which cells change in structure in order to carry out specific functions. |
| Diffusion | The net movement of molecules from a region of higher concentration to a region of lower concentration. May also be defined as the movement from a region of higher kinetic energy to a region of lower kinetic energy. |
| Digestion | A set of chemical reactions which breaks down larger complex molecules into simpler water soluble molecules. |
| Diploid phase of the life cycle | Phase of the sexual life cycle that originates with the zygote formed by fertilization of gametes. Structures in this phase have two sets of chromosomes in each nucleus. Besides the zygote, multicellular forms may also be present in this phase as in the plant and animal kingdoms. |
| Disaccharide | A carbohydrate that is composed of two simple sugar monomers. Sucrose is a common disaccharide composed of glucose and fructose. |
| Dissolve | To cause molecules to disperse from one another |
| DNA | Deoxyribonucleic acid; A double stranded helical nucleic acid molecule that functions in controlling the activities of the cell. |
| Domestic plant | One that is more or less dependent on humans for its survival. Most domesticate plants survive poorly in the wild. |
| Domestication | The process whereby the genetic make-up of a species is changed by artificial slection in such a way that the plants become dependent on humans for their survival. |
| Dominant Alllele | In a diploid organism, it is the form of the gene that masks the expression of the other allelic form of the gene fore the same trait. |
| Dormancy | Lack of growth due to internal factors within an organ such as a seed or bud |
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ecosystem |
ecological unit composed of an interactin community and its environment |
|
edaphic |
factors pertaining to the soil |
| Electrons | Negatively charged particules found in an atom that revolve around the atomic nucleus in electron clouds or orbitals. |
| Embryo | The immature plant contained within the seeds of plants |
| Emergence | The appearance of the developing seedling above ground |
| Endodermis | Layer of cells between the cortex and vascular cylinder in roots |
| Endoplasmic reticulum | An elaborate network of membranes in eukaryotic cells that may or may not have ribosomes associated with them. If ribosomes are present (rough ER), ER functions in protein synthesis; If not (smooth ER), the ER functions in lipid and membrane assembly. |
| Endosperm | The nutritive tissue in seeds that provides food for the developing embryo |
| Endosymbiotic theory | A theory that postulates that eukaryotic cells arose as a result of a symbiotic relationship between smaller prokaryotic cells living within a larger prokaryotic cell. |
| Endotoxins | Toxic chemicals produced in and retained bacteria. Upon death and decomposition of the bacteria, the toxins are released causing some forms of food poisoning. |
| Energy | The ability to do work |
| Enzyme | A protein that serves as a biological catalyst; that is, it speeds up a rate of a biochemical reaction without being used up in the process. |
| Epidermis | The outer tissue layer of plants that functions primarily in protection |
|
epiphytes |
an organism that is growing on another organisms without being parasitic |
| Equilibrium | No net movement of particles because the kinetic energy in all regions is the same. If concentration is the only factor affecting kinetic energy, then at equilibrium the concentrations are the same. |
| Ethylene | A plant hormone that is involved in fruit ripening and senescence |
| Eukaryotic cell | Cell characterized by having chromosomes with a double nuclear membrane forming a nucleus and membrane-bound organelles within the matrix. |
| Eutrophication | A naturally occurring process in which nutrients accumulate within a body of water causing an increase in algae and other organisms. Agricultural run-off and sewage effluent can accelerate the process adversely affecting water quality. |
| Evolution | Genetic changes in a population that occur over many generations. |
| Exons | Segments of DNA of eukaryotic genes that is transcribed and subsequently translated into a protein. Those segments of a gene that are expressed. |
| Exotoxin | Toxic chemicals produced inside the bacteria and secreted into the environment. Exotoxins are also responsible for food poisoning. |
| Experiment | A set of manipulations or observations of nature designed to test an hypothesis. Experiments are designed with expected outcomes in mind, assuming the hypothesis is correct. |
| Experimental Group | Part of a scientific experiment which receives the independent variable treatment. |
| F1 generation | Stands for the first filial generation. Offspring that result from the cross between the parents . |
| F2 generation | Stands for the second filial generation. Refers to the offspring that result from matings of the F1 offspring. |
| Fat | A neutral lipid that is solid at room temperature. |
| Fertilization | Fusion of male and female gametes. Results in the formation of the offspring. |
| Fibrous root system | A type of root system consisting of many branching roots |
| First Law of Thermodynamics | Energy can neither be created nor destroyed in the Universe but it can be converted from one form to another. Also called the Law of Conservation of Energy |
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food chain |
a group of organisms that are linked together in a single line by one organism feeding on another |
|
food web |
the interacting food chains within a community |
| Fruiting body | A structure in which sexual spores are produced in members of the higher fungi. Mushrooms and toadstools are examples of fruiting bodies. |