Science Terms TAKS Objective 2 Process by which molecules move from an area of high concentration to an area of low concentration def: Diffusion The movement of water across the plasma membrane from an area of high concentration to an area of low concentration. def: Osmosis State of being balanced, example maintaining body temperature or water balance in an organism. def: Homeostasis Ability to let things pass through, this is the cell membranes function. def: Permeability Protects and lines cell lets things pass in and out of the cell def: Cell membrane Chlorophyll containing organelle found in green plants and some protests def: Chloroplasts Membranes forming a type of transport system def: Endoplasmic reticulum Eukaryotic organelle in which food molecules are broken down to produce energy def: Mitochondrion Organelle involved in protein synthesis def: Ribosome Gene form for each variation of a trait of an organism def: Allele Molecule coding organisms information code, consists of a sugar, phosphate and a nitrogen base def: DNA Single Stranded molecule that forms a copy of DNA for use in protein synthesis def: RNA A part of cell division in which the nucleus divides, the end result is 2 identical daughter cells that are identical to the parent cell def: Mitosis Process by which the number of chromosomes per cell is cut in half, used by organisms to produce gametes def: Meiosis Error or change in the DNA sequence Change in nitrogen bases def: Mutation Way to find expected proportions of genotypes of offspring of a cross def: Punnet Square Branch of biology dealing with grouping an naming organisms def: Taxonomy Broadest level of classification def: Kingdom Multi-cellular consumers that eat other organisms for food def: Animals Group of prokaryotes that produce their food in unusual ways. Usually live in extreme environments def: Archaebacteria Prokaryotes living under normal conditions def: Eubacteria Heterotrophic eukaryotic consumers that absorb nutrients from decomposing wastes and dead organisms def: Fungi Stationary multicellular eukarotes that photosynthesize def: Plants Single celled eukaryotes def: Protists Single celled organisms lacking membrane bound organelles def: Prokaryotes Organism composed of cells with organelles. May be unicellular or multicellular def: Eukaryotes Includes heart, blood vessels and blood, transports nutrients and wastes within the body def: Circulatory system Receives and breaks down food and absorbs nutrients def: Digestive system Controls metabolic activities of the body def: Endocrine system Filters the blood, collects and excretes wastes def: Excretory system Protects the body from infections def: Immune system Skin and its associated structures def: Integumentary system Provides for movement of the body def: Muscular system Supports body def: Skeletal system Provides sensory function def: Nervous system Involved in the production of gametes def: Reproductive system Provides area for gas exchange in the organism def: Respiratory system A group of cells working together def: Tissue A group of tissues working together def: Organ A group of organs working together to maintain homeostasis def: Organ system