Biology 111 Exam 2 Questions & Answers Solved 100% Correct!!

The compounds of biological membranes that form a barrier to the movement of hydrophilic materials across the membrane are? - Answer-Lipids Which of the following statements about cholesterol molecules is true? - Answer-They alter the fluidity of the membrane The hydrophilic regions of a membrane protein are most likely to be found? - Answer-Exposed on the surface of the membrane Competitive inhibitors of enzymes work by? - Answer-Fitting into the active site this functions as a recognition signal for interactions between the cells? - Answer-Glycolipids The difference between tight junctions, desmosomes, and gap junctions is that? - Answer-Tight junctions desmosomes have mechanical roles, where as gap junctions facilitate communication between cells Which of the following is an example of passive transport? - Answer-Facilitated diffusion Which of the following molecules is the most likely simply to diffuse across a cell membrane? - Answer-A steroid The difference between osmosis and diffusion? - Answer-Osmosis refers specifically to the movement of water across a membrane, whereas diffusion is the movement of molecules. Osmosis moves water from a region of ___ to a region of ___? - Answer-Low concentration of dissolved material; High concentration of dissolved material Osmosis helps plant cells maintain.. - Answer-turgor pressureWhen a severely dehydrated patient is brought to the hospital, an IV of normal saline is started immediately. Distilled water is not used because? - Answer-It would cause the patients blood cells to swell and eventually burst The speed and direction of ions as they move into and out of the cell are determined by the? - AnswerConcentration gradient and electrochemical imbalances In facilitated diffusion, the diffusion rate of a specific molecule across a membrane does not continue to increase as the concentration difference of the molecule across the membrane increases. This is the case because? - Answer-The carrier proteins are saturated. Plant cells transport sucrose across the vacuole membrane against its concentration gradient by a process known as? - Answer-Active transport How does the second law of thermodynamics apply to organisms? - Answer-To maintain order, life requires a constant input of energy Which of the following represents potential energy? - Answer-- Chemical bonds - Concentration gradient - Electric charge imbalance The sum total of all the chemical reactions in a living structure is called its? - Answer-Metabolism When ADP gains a phosphate to form ATP? - Answer-Energy is consumed Large molecules that contain carbon and are held together by covalent bonds are categorized as? - Answer-Macromolecules How do competitive and non-competitive enzyme inhibitors differ? - Answer-Competitive inhibitors bind to the active site, whereas non-competitive inhibitors change the shape of the active site Molecules containing a large number of hydroxyl groups are? - Answer-Highly soluble in waterAn essential functional group involved in cellular energy transfer is the ___ group? - Answer-Phosphate In condensation (AKA: dehydration synthesis) reactions, the atoms that make up a water molecule are derived from? - Answer-Both of the reactants Which of the following is responsible for making every amino acid unique? - Answer-"R" group Starch and glycogin which are both polysaccharides differ in their functions in that starch is ____ whereas glycogin ____? - Answer-The principle energy storage compound of plants; Is the main energy storage of animals The amino acids of protein keratin are arranged in a helix. This secondary structure is stabilized by? - Answer-Hydrogen bonds Quaternary structure is found in proteins? - Answer-Composed of two or more polypeptides subunits A ____ protein is a protein that has become nonfunctional due to the loss of it's three dimensional structure? - Answer-Denatured A molecule with the formula C16 H30 O15 is a? - Answer-Carbohydrate The main function of cellulose, the most abundant organic compound on earth is? - Answer-To provide mechanical strength to plant cell walls The side chain of leucine is a hydrocarbon. In a folded protein, where would you expect to find the leucine? - Answer-"Both A and B" - In the interior of a cytoplasmic enzyme - On the exterior of a protein embedded in a membrane A fat contains fatty acids and? - Answer-GlycerolNegative feedback in a sequence of chemical reactions involves a chemical that appears ___ in the sequence and ____ reaction? - Answer-Late; Inhibits an earlier The basis of nucleic acids are purines or pyrimidines. Purines and pyrimidines are distinguished by the fact that? - Answer-Purines are double-ringed structures, whereas pyrimidines are single-ringed structures Which of the following is not a difference between DNA and RNA? - Answer-DNA is polymer whereas RNA in monomer Unsaturated fatty acids do not pack together due to? - Answer-Kinks in the hydrocarbon chains ribozymes When placed in a hypertonic solution, animal cells - Answer-Shrink metabolism is - Answer-the total of all chemical reactions in an organism activation energy is - Answer-the minimum amount of energy needed to start a chemical reaction transition state is - Answer-an unstable grouping of atoms that exists momentarily in the course of a reaction, when a system is highest in energy. 3 important properties of catalysts - Answer-speed up reaction rates by lowering the activation energy of a reaction -are not consumed by the reaction- no change - are present in very small amounts compared to the other reactants conformational change - Answer-a slight change in the three dimensional structure of a protein that may result in a change in activity. often involved in regulation of enzyme ed fit - Answer-the change in shape of the active site of an enzyme so that it binds more snugly to the substrate, induced by entry of the substrate. like shaking hands substrate - Answer-the substance acted upon by an enzyme denaturation - Answer-a process in which a protein unravels and loses its native conformation, thereby becoming biologically inactive. denaturation occurs under extreme conditions of ph, salt concentration, and temperature. competitive inhibitor - Answer-a substance that reduces the activity of an enzyme by entering the active site in place of the substrate whose structure it mimics. non-competitive inhibitor - Answer-a substance that reduces the activity of an enzyme by binding to a location remote from the active site, changing its conformation so that it no longer binds to the substrate. allosteric regulation - Answer-the binding of a regulatory molecule to a protein at one site that affects the function of the protein at a different site. feedback inhibition - Answer-a method of metabolic control in which the end product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway. (negative feedback) --> switching off a metabolic pathway by the form of its end product enzymes - Answer-are larger than their substrates changes shape when it binds to a substrate. lower the activation energy. are highly specific. may orient substrates, induce strain, or temporarily add chemical groups.