science+vocab

18.1 Vocabulary

1. diffusion-the movement of particles from the regions of lower density. 2. osmosis -the diffusion of water through a semipermeable membrane. 3. molecules -small particles. 4. semipermiable -only certain substances can pass through. 5. passive transport -the movement of substances across a cell membrane without the use of energy by the cell. 6. active transport -the movement of substances across the cell membrane that requires the cell to use energy. 7. endocytosis -the process by which a cell membrane surrounds a particle and encloses the particle in a vesicle to bring the particle into the cell. 8. exocytosis -the process in which a cell releases a particle by enclosing the particle in a vesicle that then moves to the cell surface and fuses with the cell membrane. 18.2 Vocabulary 1. photosynthesis -the process by which plants, algae, and some bacteria use sunlight, carbon dioxide, and water to make food. 2. cellular respiration -the process by which cells use oxygen to produce energy from food. 3. fermentation -the breakdown of food without the use of oxygen. 4. respiration -breathing. 18.3 Vocabulary 1. Cell cycle -the life of a cell. (2-6 get from pg 538 & 539) 2. Interphase -before mitosis begins, chromosomes are copied. Each chromosome is then two chromatids. 3. Prophase -mitosis begins. The nuclear membrane dissolves. Chromosomes condense into rodlike structures. 4. Metaphase -the chromosomes line up along the equator of a cell. Homologous chromosomes pair up. 5. Anaphase -the chromatids separate and move to opposite sides of the cell. 6. Telophase -a nuclear membrane forms around each set of chromosomes, and the chromosomes unwind. Mitosis is complete. 7. Cytokinesis -in cells that lack a cell wall, the cell pinches in two. In cells that have a cell wall, a cell plate forms between the two cells. 18.4 Vocabulary 1. homeostasis -the maintenance of a stable environment in the body. 2. feedback mechanism -a cycle of events in which information from one step controls or affects a previous step.