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MCAT Prep Biology

Subjects : mcat, science
Instructions:
  • Answer 50 questions in 30 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. A contractile protein connecting microtubules in the '9+2- arrangement of cilia and eukaryotic flagella. The contraction of dynein produces the characteristic movement of these structures.






2. An ion channel that is oepend or closed based on the electrical potential across the plasma membrane. Once opened - the channel allows ions to cross the membrane according to their concentration gradients. Examples are the Na+ and K+ voltage - gated






3. A protein that is associated with the plasma membrane of a cell - but that is not embedded in the lipid bilayer. Peripheral proteins typically associate with embedded proteins through hydrogen bonding or electrostatic interactions.






4. A period of time following an action potential during which no additional action potential can be evoked regardless of the level of stimulation. (usually because Na+ channel closed whle K+ efflux)






5. The movement of air into the respiratory tract. Inspiration is an active process - requiring contraction of the diaphragm.






6. A nucleoside with one or more phosphate gropus attached. Nucleoside triphosphates (NTPs) are the building blocks of RNA and are also used as energy molecules - especially ATP. Deoxynucleoside triphosphates (dNTPs) are the building blocks of DNA; in t






7. The reduced from (carries electrons) of FAD (flavin adenine dinucleotide). this is the other main electron carrier in cellular respiration (NADH is the most common).






8. An organism that will use oxygen (aerobic metabolism) if it is available - and that can ferment (anaerobic metabolism) if it is not.






9. A cell that produces bone.






10. A mechanism for increasing tension (contractile length) in a muscle by activating more motor units.






11. A fibrous - connective - tissue protein taht has the ability to recoil to its original shape after being stretche.d Elastin is found in great amounts in lung tissue - arterial tissue - skin - and the epiglottis.






12. A methylated guanine nucleotide added to the 5' end of eukaryotic mRNA. The cap is necessary to initiate translation of mRNA


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






14. The reduction of pyruvate to either ethanol or lactate in order to regenerate NAD+ from NADH. Fermentation occurs in the absence of oxygen - and allow glycolysis to continue under those conditions.






15. A bundle of skeletal muscle cells. Fascicles group together to form skeletal muscles.






16. Multiple sites of replication found on large - linear eukaryotic linear eukaryotie chromosomes.






17. The valves in the heart that separate the ventricles from the arteries. The pulmonary semilunar valve separates the right ventricle from the pulmonary artery - and the aortic semilunar valve separates left ventricle from the aorta. These valves close






18. A nucleotide sequence on DNA that contians three elemtns: a coding sequence for one or more enzymes - *a coding sequence for a regulatory protein - and upstream regulatory sequences where the regulatory proteins can bind. An example is the lac operon






19. The perio dof tim ein a woman's life when ovulation and menstruation cease. Menopause typically begins in the late 40s.






20. The pressure measured in the arteries while the ventricles are relaxed (during diastole).






21. An insulating layer of membranes wrapped around the axons of almost all neurons in the body. Myelin is essentially the plasma membranes of specialized cells; Schwann cells in the peripheral nervous system - and oligodendrocytes in the central nervous






22. Also called falopian tubes - these tubes extend laterally from their side of the uterus and serve as a passageway for the ocyte to travel from the ovary to the uterus. This is also the normal site of fertilization. Severing of the uterine tubes (tuba






23. Ribosomal RNA; the type of RNA that associates with ribosomal proteins to make a functional ribosome. It is thought that the rRNA has the peptidyl transferase activity.






24. Formerly called the cardiac sphincter - this sphincter marks the entrance to the stomach. Its function is to prevent reflux of acid stomach contents into the esophagus; note that it does **not regulate entry into the stomach.






25. The central structure of the diencephalon of the brain. the thalamus acts as a relay station and major integrating area for sensory impulses.






26. A substance secreted by embryonic testes that causes the regression of the Mullerian ducts.






27. A nucleotide sequence in RNA that contains protein - coding information. Exons are typically separated by introns (intervening sequences) that are spliced out prior to translation.






28. An activated B cell that is secreting antibody.






29. A point mutation in which a pyrimidine is substitued for a purine - or vice versa.






30. The phase of mitosis during which the cell physically splits into two daugter cells. Cytokinesis begins near the end of anaphase - and is completed during telophase.






31. The third stage of cellular respiration - in which acetyl - CoA is combined with oxaloacetate to form citric acid. The citric acid is then decarboxylated twice and isomerized to recreate oxaloacetate. In the process - 3 molecules of NADH - 1 molecule






32. A diploid cell that can undergo mitosis to form more spermatogonium - and can also be triggered to undergo meiosis to form sperm.






33. The first generation of offspring from a given genetic cross.






34. In skeleta and cardiac muscle tissue - a filament composed of actin - tropomyosin - and troponin. Thin filaments are attached to teh Z lines of the sarcomers and slide over thick filaments during muscle contraction.






35. A digestive accessory organ near the liver. The gallbladder stores and concentrates bile produced by the liver - and is stimulated to contrat by cholecystokin (CCK).






36. An inactive precursor of an enzyme - activated by various methods (acid hydrolysis - cleavage by another enzyme - etc.)






37. A system of blood vessels where the blood passes from arteries to capillaries to veins - then through a second set of capillaries - and then through a final set of veins. THere are two portal systems in the body - the hepatic portal system and the hy






38. One of the four aromatic bases found in DNA and RNA. Guanine is a purine; it pairs with cytosine.






39. 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






40. An asexual method of bacterial reproduction that serves only to increase the size of the population; ther is no introduciton of gnetic diversity. THe bacterium simply grows in size until it has doubled its cellular components - then it replicates its






41. An immune reaction directed against normal (necessary ) cells.Fo example - diabets melitus (typeI) is an autoimmun reaction directed against teh beta cells of the pancrease (destorying them and preventing insulin secretion) and aginst insulin itself.






42. One of the four aromatic bases found in DNA and RNA; also a component of ATP - NADH - and FADH2. Adenine is apurine; it pairs with thymine (in DNA) and with uracil (in RNA)






43. An organism that relies on a chemical source of energy (such as ATP) instead of light (which phototrophs).






44. An incrase in the fragility of the membranes of sperm cells when exposed to the female reproductive tract. Capacitation is required sot aht the acrosomal enzymes can be relased to faciliate fertilization.






45. The blood vessels taht carry blood to and from cardiac muscle. The coronary arteries branch off teh aorta and carry oxygenated blood to the cardiac tissue. The coronary veins collect deoxygenated blood from teh cardiac tissue - merge to form teh coro






46. The division between neighboring cardiac muscle cells. Intercalcated discs include gap junctions - which allow the cells to function as a unit.






47. 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






48. An organism that requires the aid of a host organism to survive - and that harms the host in the process.






49. A hormone released from the hypothalamus that triggers the anterior pituitary to secrete FSH and LH.






50. A junction between cells - consisting of a protein channel called a connexon on each of the two cells that connect to form a single channel between teh cytoplasms of both cells. Gap junctions allow small molecules to flow between teh cells - and are