GED Science Test: Knowing How Cells Survive and Thrive - dummies

GED Science Test: Knowing How Cells Survive and Thrive

By Murray Shukyn, Achim K. Krull

You will need to understand how cells survive and thrive for the GED Science test. Cells live, breathe, and procreate by engaging in various cellular processes. You may encounter questions that require you to know what a specific process is all about based on a passage. Following are the names of the different cellular processes, along with a brief description of each:

  • Metabolism: Chemical reactions within living cells that maintain the cell’s life. Metabolism is broken down into two functions:

    • Catabolism breaks down organic matter to create energy.

    • Anabolism uses energy to build complex molecules out of smaller chemical units.

  • Osmosis: The movement of water molecules across a partially permeable membrane. Osmosis enables cells to “take a drink.”

  • Phagocytosis: The process of a cell ingesting a particle. In simple terms, the cell is eating. The cell senses a particle or another cell near its membrane and then surrounds the particle. After surrounding the particle, the phagocyte (the cell ingesting the particle) breaks down its own outer membrane, bringing the particle inside itself.

  • Photosynthesis: The process by which plants and some single-cell organisms use light to convert water and carbon dioxide into carbohydrates and oxygen.

  • Respiration: The process of breaking down nutrients to produce energy for a cell. The byproducts of respiration are carbonic acids and carbon dioxide.

  • Fermentation: A metabolic process in which bacteria, yeasts, or other microorganisms convert sugar to acids, gases, or alcohol.

  • Reproduction: Cells reproduce through cytokinesis (cell division), which occurs in one of the following two ways:

    • Mitosis: Most cells reproduce by dividing into two identical daughter cells, each containing a complete set of DNA (genetic material). The daughter cells also happen to be identical to the parent cell. Talk about a close family!

    • Meiosis: This process, used to create sex cells — eggs and sperm used to reproduce — consists of splitting a cell twice to form four cells (gametes), each of which contains half the DNA the organism needs to develop. When the sperm fertilizes the egg, a cell (zygote) is formed that contains a complete set of DNA.