1.+Living+things+are+both+similar+to+and+different+from+each+other

MAJOR UNDERSTANDINGS 1.1a Living things are composed of cells. Cells provide structure and carry on major functions to sustain life. Cells are usually microscopic in size. 1.1b The way in which cells function is similar in all living things.  1.1c Most cells have cell membranes, genetic material, and cytoplasm. Some cells have a cell wall and chloroplasts. Many cells have a nucleus. 1.1d Some organisms are single cells; others, including humans, are multicellular. 1.1e Cells are organized for more effective functioning in multicellular organisms.  1.1f Many plants have roots, stems, leaves, and reproductive structures. These organized groups of tissues are responsible for a plant's life activities. 1.1g Multicellular animals often have similar organs and specialized systems for carrying out major life activities. 1.1h Living things are classified by shared characteristics on the cellular and organism level. 1.2a Each system is composed of organs and tissues which perform specific functions and interact with each other.  1.2b Tissues, organs, and organ systems help to provide all cells with nutrients, oxygen, and waste removal. 1.2c The digestive system consists of organs that are responsible for the mechanical and chemical breakdown of food.  1.2d During respiration, cells use oxygen to release the energy stored in food.  1.2e The excretory system functions in the disposal of dissolved waste molecules, the elimination of liquid and gaseous wastes, and the removal of excess heat energy. 1.2f The circulatory system moves substances to and from cells, where they are needed or produced, responding to changing demands. 1.2g Locomotion, necessary to escape danger, obtain food and shelter, and reproduce, is accomplished by the interaction of the skeletal and muscular systems, and coordinated by the nervous system. 1.2h The nervous and endocrine systems interact to control and coordinate the body's responses to changes in the environment, and to regulate growth, development, and reproduction. 1.2i The male and female reproductive systems are responsible for producing sex cells necessary for the production of offspring. 1.2j Disease breaks down the structures or functions of an organism.