The level of organization that is more complex than a atom but less complex than an organelle is a(n) __________ . Show Molecules may be assembled into a microscopic structure called a(n) _______ which carries out specific functions within a cell. The simplest level of organization that can carry out all of the functions of life is a(n) ______ . A _____ is a group of similar cells that act as a functional unit. Your brain is an example of a(n) _____ . A group of organisms that belong to the same species and live in the same place is called a(n) _______ . A biological community together with its physical habitat constitutes a(n) ________ . Living organisms and non-living systems have numerous characteristics in common, but only organisms - Which of the following BEST describes the theory of natural selection? Some individuals have genes that increase their chances for survival and reproduction. These individuals are more likely to reproduce and pass on their genes, causing their genes to become more common in the next generation. The skeletons of mammals that existed 150 million years ago are different from the skeletons of mammals that exist today. The front limbs of humans, bats, birds, and whales all have a similar bone structure. All vertebrates contain the protein hemoglobin, but the structure of the hemoglobin molecule varies from one species to the next. Your roommate take a daily multivitamin and has had no colds during the past 2 years. You never take a multivitamin and have had 3 colds during the past 2 years. Therefore you hypothesize that taking a multivitamin reduces the chances of getting a cold. You dissect 10 frogs and observe that each one has 1 heart and 2 kidneys. Therefore you hypothesize that all frogs have 1 heart and 2 kidneys. All mammals, by definition, have hair. Since your pet snake does not have hair you conclude she is not a mammal. Overwhelming evidence indicates that smoking increases the risk of getting lung cancer. Therefore you conclude that if you smoke your chances of getting lung cancer will increase. The roots of a plant grow toward a source of water. The body temperature of a dog is more stable than the temperature of its environment. A cat is composed of organ systems, which are composed of organs, which are composed of tissues, which are composed of cells. A bacterial cell divides to form two new cells. In order to carry out essential life functions such as growth, development, and movement, a duck must eat. In 1980, scientists determined that 2% of the honey bees in Texas had a gene that makes them more aggressive. By 2005, the frequency of this gene in the Texas honeybee population had increased to 15%.. An Introduction to the Human Body OpenStaxCollege Learning ObjectivesBy the end of this section, you will be able to:
Before you begin to study the different structures and functions of the human body, it is helpful to consider its basic architecture; that is, how its smallest parts are assembled into larger structures. It is convenient to consider the structures of the body in terms of fundamental levels of organization that increase in complexity: subatomic particles, atoms, molecules, organelles, cells, tissues, organs, organ systems, organisms and biosphere ([link]). Levels of Structural Organization of the Human Body The organization of the body often is discussed in terms of six distinct levels of increasing complexity, from the smallest chemical building blocks to a unique human organism.
The Levels of OrganizationTo study the chemical level of organization, scientists consider the simplest building blocks of matter: subatomic particles, atoms and molecules. All matter in the universe is composed of one or more unique pure substances called elements, familiar examples of which are hydrogen, oxygen, carbon, nitrogen, calcium, and iron. The smallest unit of any of these pure substances (elements) is an atom. Atoms are made up of subatomic particles such as the proton, electron and neutron. Two or more atoms combine to form a molecule, such as the water molecules, proteins, and sugars found in living things. Molecules are the chemical building blocks of all body structures. A cell is the smallest independently functioning unit of a living organism. Even bacteria, which are extremely small, independently-living organisms, have a cellular structure. Each bacterium is a single cell. All living structures of human anatomy contain cells, and almost all functions of human physiology are performed in cells or are initiated by cells. A human cell typically consists of flexible membranes that enclose cytoplasm, a water-based cellular fluid together with a variety of tiny functioning units called organelles. In humans, as in all organisms, cells perform all functions of life. A tissue is a group of many similar cells (though sometimes composed of a few related types) that work together to perform a specific function. An organ is an anatomically distinct structure of the body composed of two or more tissue types. Each organ performs one or more specific physiological functions. An organ system is a group of organs that work together to perform major functions or meet physiological needs of the body. This book covers eleven distinct organ systems in the human body ([link] and [link]). Assigning organs to organ systems can be imprecise since organs that “belong” to one system can also have functions integral to another system. In fact, most organs contribute to more than one system. Organ Systems of the Human Body Organs that work together are grouped into organ systems.
Organ Systems of the Human Body (continued) Organs that work together are grouped into organ systems.
The organism level is the highest level of organization. An organism is a living being that has a cellular structure and that can independently perform all physiologic functions necessary for life. In multicellular organisms, including humans, all cells, tissues, organs, and organ systems of the body work together to maintain the life and health of the organism. Chapter ReviewLife processes of the human body are maintained at several levels of structural organization. These include the chemical, cellular, tissue, organ, organ system, and the organism level. Higher levels of organization are built from lower levels. Therefore, molecules combine to form cells, cells combine to form tissues, tissues combine to form organs, organs combine to form organ systems, and organ systems combine to form organisms. Review QuestionsCRITICAL THINKING QUESTIONSName the six levels of organization of the human body. Chemical, cellular, tissue, organ, organ system, organism. The female ovaries and the male testes are a part of which body system? Can these organs be members of more than one organ system? Why or why not? The female ovaries and the male testes are parts of the reproductive system. But they also secrete hormones, as does the endocrine system, therefore ovaries and testes function within both the endocrine and reproductive systems. Glossarycellsmallest independently functioning unit of all organisms; in animals, a cell contains cytoplasm, composed of fluid and organellesorganfunctionally distinct structure composed of two or more types of tissuesorgan systemgroup of organs that work together to carry out a particular functionorganismliving being that has a cellular structure and that can independently perform all physiologic functions necessary for lifetissuegroup of similar or closely related cells that act together to perform a specific functionWhich is the simplest level of organization in life?Level 1: Cells
The first and most basic level of organization is the cellular level. A cell is the basic unit of life and the smallest unit capable of reproduction. While cells vary greatly in their structure and function based on the type of organism, all cells have a few things in common.
What is the smallest level of organization in the human body?A cell is the smallest independently functioning unit of a living organism. Even bacteria, which are extremely small, independently-living organisms, have a cellular structure.
What are the levels of organization from simplest to complex?The major levels of organization in the body, from the simplest to the most complex are: atoms, molecules, organelles, cells, tissues, organs, organ systems, and the human organism. See below Figure 1.1.
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What is the simplest level of organization that can carry out all of the functions of life?
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