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Organism. An organism is defined in a medical dictionary as any living thing that functions as an individual. [1] Such a definition raises more problems than it solves, not least because the concept of an individual is also difficult. Many criteria, few of them widely accepted, have been proposed to define what is an organism.
Minor intermediate ranks are not shown. A species ( pl.: species) is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. [ 1] It is the basic unit of classification and a taxonomic rank of an organism, as well as a ...
Category. v. t. e. An ecosystem (or ecological system) is a system that environments and their organisms form through their interaction. [2] : 458 The biotic and abiotic components are linked together through nutrient cycles and energy flows. Ecosystems are controlled by external and internal factors.
Biochemistry is the study of chemical processes within and relating to living organisms. Molecular biology is the branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including molecular synthesis, modification, mechanisms, and interactions.
Ontogeny is the process of development of an individual organism from the zygote through the embryo to the adult form. In the latter half of the twentieth century, social scientists debated whether human behaviour was the product of nature (genes) or nurture (environment in the developmental period, including culture).
Evolution in organisms occurs through changes in heritable characteristics—the inherited characteristics of an organism. In humans, for example, eye colour is an inherited characteristic and an individual might inherit the "brown-eye trait" from one of their parents. [21]
Reproduction (or procreation or breeding) is the biological process by which new individual organisms – "offspring" – are produced from their "parent" or parents. There are two forms of reproduction: asexual and sexual . In asexual reproduction, an organism can reproduce without the involvement of another organism.
Natural selection acts on an organism's phenotype, or physical characteristics. Phenotype is determined by an organism's genetic make-up (genotype) and the environment in which the organism lives. When different organisms in a population possess different versions of a gene for a certain trait, each of these versions is known as an allele. It ...