The Common Processes of All Living Organisms

Biology revolves around understanding living organisms and their processes. Organisms can be classified into three categories: living (actively performing life processes), dead (once living but now ceased life processes), and never alive (non-biological entities). All living organisms carry out seven core processes represented by the mnemonic MRS GREN: Movement, Reproduction, Sensitivity, Growth, Respiration, Excretion, and Nutrition.

Categorizing examples clarifies these concepts: dogs and Venus fly traps are living; roast chicken is dead; and bricks have never been alive. Movement distinguishes living from non-living things; for example, a car moves but is not living, while an animal moves itself for survival. Plant movements may be slow and imperceptible, yet they are crucial for survival, such as phototropism.

Life cycles vary by species—illustrated through frogs, trees, and butterflies—showing distinct stages and the processes involved at each stage. Notably, plants and seeds are living organisms that may not exhibit all life processes simultaneously. Key principles include the universality of life processes, the origin of life from reproduction, and purposeful movement toward survival goals, with lifecycle cyclicality indicating that processes are not necessary in every stage.