Chapter 1 lecture (exploring life)

Chapter 1 lecture (exploring life) - Chapter 1 Biology is...

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Chapter 1 Biology is the scientific study of life. Biologists explore life from the microscopic to the global scale Life’s basic characteristic is a high degree of order. Each level of biological organization has emergent properties. Biological organization is based on a hierarchy of structural levels, each building on the levels below. ° At the lowest level are atoms that are ordered into complex biological molecules. ° Biological molecules are organized into structures called organelles, the components of cells. ° Cells are the fundamental unit of structure and function of living things. Some organisms consist of a single cell; others are multicellular aggregates of specialized cells. Whether multicellular or unicellular, all organisms must accomplish the same functions: uptake and processing of nutrients, excretion of wastes, response to environmental stimuli, and reproduction. ° Multicellular organisms exhibit three major structural levels above the cell: similar cells are grouped into tissues, several tissues coordinate to form organs, and several organs form an organ system. For example, to coordinate locomotory movements, sensory information travels from sense organs to the brain, where nervous tissues composed of billions of interconnected neurons— supported by connective tissue—coordinate signals that travel via other neurons to the individual muscle cells. ° Organisms belong to populations, localized groups of organisms belonging to the same species. ° Po pulations of several species in the same area comprise a biological community. ° Populations interact with their physical environment to form an ecosystem. ° The biosphere consists of all the environments on Earth that are inhabited by life.
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Organisms interact continuously with their environment. Each organism interacts with its environment, which includes other organisms as well as nonliving factors. Both organism and environment are affected by the interactions between them. The dynamics of any ecosystem include two major processes: the cycling of nutrients and the flow of energy from sunlight to producers to consumers. ° In most ecosystems, producers are plants and other photosynthetic organisms that convert light energy to chemical energy. ° Consumers are organisms that feed on producers and other consumers. All the activities of life require organisms to perform work, and work requires a source of energy. ° The exchange of energy between an organism and its environment often involves the transformation of energy from one form to another. ° In all energy transformations, some energy is lost to the surroundings as heat. ° In contrast to chemical nutrients, which recycle within an ecosystem, energy flows through an ecosystem, usually entering as light and exiting as heat.
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