KSU Bio 198 Exam 5 Review Questions and Correct Answers

Describe the First and Second Laws of Thermodynamics and explain why they are important to the cellular energetics. 1st - energy cannot be created or destroyed, only change forms. • This is important because all living things need a constant energy source (the sun) 2nd - when transforming energy, some is lost as heat (10% between trophic levels) Define endergonic and exergonic reactions and describe how they are linked in cellular energetics. Endergonic - requires energy (hydrolysis; splitting molecules) Exergonic - releases energy (condensation; putting molecules together) Describe the basic structure of ATP, understand how it stores and releases cellular energy (i.e. its role as an energy carrier), and the relationship of ATP to exergonic and endergonic reactions. ATP is the energy carrier of cells. It powers cell actions. short term usable energy Adenine, ribose (5-carbon sugar) and 3 phosphate groups ATP loses a phosphate group (exergonic) which creates ADP ADP gains a phosphate group (endergonic) which created ATP Describe oxidation and reduction reactions and explain their relationship to endergonic and exergonic reactions. Oxidation - electrons are REMOVED from substances when breaking molecules (endergonic) Reduction - electrons are ADDED. molecules are synthesized. (exergonic) Oxidation and reduction ALWAYS happen together (redox reactions) Describe the process of diffusion and the factors that influence diffusion rates. Diffusion - moving from high concentration to low concentration - small non-polar molecules diffuse best (carbon dioxide, oxygen) - CAN occur across membranes Describe selective permeability and how it influences movement of materials across plasma membranes, including what types of molecules easily pass through the membrane and what cannot. Selective permeability - allows some things to pass through, but not all. Membrane is asymmetric (inside and outside are different). Only non-polar molecules can pass through because the plasma membrane is polar (their charges are repelled)