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MCAT Prep Biology

Subjects : mcat, science
Instructions:
  • Answer 50 questions in 15 minutes.
  • If you are not ready to take this test, you can study here.
  • Match each statement with the correct term.
  • Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.
1. An enzyme that unwinds the double helix of DNA and separates the DNA strands in preparation for DNA replication.






2. The flexible membrane in teh chochlea that supports the organ of Corti (structure which contains the hearing receptors). The fibers of the basilar membrane are short and stiff near the oval windown and long and fleaxible near the apex of the cochlea.






3. A function in the reproductive system - controlled by the parasympathetic nervous system - that includes erection (via dilation of erectile arteries) and lubrication.






4. Small fragments of DNa produced on the lagging strand during DNa replication - joined later by DNA ligase to form a complete strand.






5. The current understanding of membrane structure - in which teh membrane iscomposed of a mix o lipids and proteins (a mosaic) that are free to move fluidly among themselves.






6. A carrier protein that transports two molecules across the plasma membrane in the same direction. For example - the Na+- glucose cotransporter in intestinal cells is a symporter.






7. The membrane that separates the middle ear from the inner ear.






8. A neuron that arries information (action potentials) to the central nervous system; a sensory neuron.






9. The enzyme that catalyzes the phosphorylation of fructose -6- phosphate to form fructose -1-6- bisphosphate in the third step of glycolysis. This is the main regulatory step of glycolysis. PFK is feedback - inhibited by ATP.






10. A thick - transpartent coating rich in glycoproteins that surrounds an oocyte.






11. A dense grwoth of bacteria that covers the surface of a petri dish.






12. The fourth of meiosis I. Telophase I is identical to mitotic telophase - except that the number of chromosoms is now reduced by half. After this phase the cell is considered to be haploid. Note however - that the chromosomes are still replicated - an






13. An embryonic structure particularly important in egg - laying animals because it contains the yolk - the only source of nutrients for the embryo developing inside the egg. In humans - the yolk sac is very small (since mammals get their nutrients via






14. A chemical secreted by a T cell (usually the helper Ts) that stimulates activation and proliferation of other immune system cells.






15. A globular protein that ssociated with tropomyosin as part of the thin filament of the sarcomere. Troponin binds Ca2+ - which causes the conformaiton change in tropomyosin required to expose the myosin - binding sites on actin and initiate muscle con






16. The force required to resist the movement of water by osmosis. Osmotic pressure is essentialy a measure of the concentration of a solution. A solution that is hyighly concnetrated has a strong tendency to draw water into itself - so the pressure requ






17. The movement of a substance across a membane via pressure. In the kidney - filtration refers specifically to the movement of plasma across the capillary walls fo the glomerulus - into the capsule and tubule of the neprhon. Filtration at teh glomerulu






18. An activated B cell that is secreting antibody.






19. The mechanism that ensures tehat skeletal muscle contraction does not occur without neural stimulation (excitation). A trest - cytosolic [Calcium] is low - and the troponin - tropomyosin complex covers the myosin - binding sites on actin. When the mu






20. An electrical potential established across the plasma membrane of all cells by the Na+/K+ ATPase and the K+ leak channels. In most cells - the resting membrane potential is approximately -70 mV with respect to the outside of the cell.






21. The movement of water (the solvent) from its region of high concentration to its region of low concentration. NOte that the water concnetration gradient is opposite to the solute concentration gradient - since where solutes are concentrated - water i






22. Cells that possess MHC II (B cells and macrophages) and are able to display bits of ingested antigen on their surface in order to activate T cells. See also 'MHC'






23. A mature - dormant osteoblast.






24. Cranial nerve pair X. The vagus nerves are very large mixed nerves (They carry both sensory input and motor input) that innervate virtually every visceral organ. They are especially important in transmitting parasympathetic input to the heart and dig






25. The three small bones found in the middle ear (the malleus - the incus - and the stapes) that help to amplify the vibrations from sound waves. The malleus is atached to the tympanic membrane and the stapes is attached to the oval window of the cochle






26. The clear portion of the tough outer layer of teh eye ball - found over the iris and pupil






27. The osmotic pressure in the blood vessels due only to plasma proteins (primarily albumin) --> causes water to rush back into capillaries at end.






28. The depolarzation of the motor end plate on a muscle cell.






29. A blood clot that forms in an unbrokened blood vessel. Thrombi are dangerous they can break free and begin travelin in the bloodstream (become an embolus). Emboli ultimately become stuck in a small vessel and prevent adequate blood delivery to tissue






30. The energy in a system that can be used to drive chemical reactions. If the change in free energy of a reaction (Delta G - the free energy of the products minus the free energy of the energy of the reactants) is negative - the reaction will occur spo






31. A vein connecting the capillary bed of the intestines with the capillary bed of the liver. This allows amino acids and gluocse absorbed from the intestines to be delivered first to the liver for processing before being transported throughout the circ






32. The pressure in the (theoretical) space between the lung surface and the inner wall of the chest cavity.






33. A large - mature - ovarian follicel with a well - developed antrum and a secondary oocyte. Ovulation of the oocyte occurs from this type of follicle.






34. The movement of the membrane potential of a cell away from rest potential in a more negative direction.






35. The product of glycolysis; 2 pyruvic acid (pyruvate) molecules are produced from a single glucose molecule. In the absence of oxygen - pyruvic acid undergoes fermentation and is reduced to either lactic acid or ethanol; in the presence of oxygen - py






36. One of the four basic tissue types in the body (epithelial - connective - muscle - and nervous). Connective tissue is a supportive tissue consisting of a relatively few cells scattered among a great deal of extracellular material (matrix) - and inclu






37. A portion of DNA that codes for some product - usually a protein - including all regulatory sequences. Some genes code for rRNA and tRNA - which are not translated.






38. A molecule formed by joining many monosaccharides together. POlysaccharides are typically energy- storage molecules (glycogen in animals - starch in plants) or structural molecules (cellulose in plants - chitin in exoskeletons).






39. The primary membrane lipid. Phospholipids consist of a glycerol molecule esterified to two fatty acid chains and a phosphate molecule. Additional - highly hyrohpilic groups are attached to the phosphate - making this molecule extremely amphipathic.






40. A cell surface receptor associated with an intracellular protein that binds and hydrolyzes GTP. When GTP is bound - the protein is active - and can regulate the activity of adenylyl cyclease; this modifies the intracellular levels of second messenger






41. The first phase of mitosis. During prophase the replicated chromosomes condense - the spindle is formed - and the nuclear envelope breaks apart into vessicles.






42. Muscles that help focus light on teh retin by controlling the curvature of the lens of the eye.






43. The outer protein coat of a virus (the whole coat)






44. A relatively direct connection between a sensory neuron and a motor neuron that allows an extremely rapid response to a stimulus - often without conscious brain involvement.






45. A microscopic space between the axon of one neuron and the cell body or dendrites of a secon neruon - or between the axon of a neuron and an organ.






46. Heterogeneous nuclear RNA; the primary transcript made in eukaryotes before splicing.






47. One of several vessels that carry oxygenated blood from the lungs to the left atrium of the heart.






48. A layer of cells surroudning the granulosa cells of the follicles in an ovary. Thecal cells help produce the estrogen secreted from the follicle during the first phase of the ovarian cycle.






49. One of the three primary (embryonic) germ layers formed during gastrulation. Endoderm ultimately forms internal structures - such as the inner lining of the GI tract and glandular organs.






50. An organelle surrounded by a double=membrane (two lipid bilayers) where ATP production takes place. The interior (matrix) is where PDC and the Krebs cycle occur - and the inner membrane contains the enzymes of the electron trasport chain and ATP synt