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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. Excitatory postsynaptic potential; a slight depolarization of a postsynaptic cell - bringing the membrane potential of that cell closer to the threshold for an action potential.






2. The portion of an integral membrane protein that passes through the lipid bilayer.






3. 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.






4. A steroid hormone produced by the corpus luteum in the ovary during the second half of the menstrual cycle Progesterone maintains and enhances the uterine lining for the possible implantation of a fertilized ovum. It is the primary hormone secreted d






5. A string of several hundred adenine nucletodies added to the 3' end of the eukaryotic mRNA.






6. The portion of the ear consisting of the pinna and the external auditory canal. The outer ear is separated from the middle ear by the tympanic membrane (the eardrum).






7. 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






8. A passageway leading from behind the nasal cavity to the trachea. The pharynx is divided into three regions - named for their location. The nasopharynx is behind the nasal cavity - the oropharynx is behind the oral cavity - and the laryngopharynx is






9. A blood protein produced by the liver. Albumin helps to mantain blood osmotic pressure (oncotic pressure)






10. The return of membrane potential to normal resting values after a depolarization of hyperpolarization.






11. The allele in a heterozygous genotype that is expressed; the phenotype resulting from either a heterozygous genotype or a homozygous dominant genotype.






12. The layer of connective tissue directly under the mucosa of an open body cavity.






13. 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






14. Steroid hormones secreted from the adrenal cortex. The two major classes are teh mineralocorticoids and glucocorticoids. Aldosterone is the principal mineralocorticoid - and cortisol is the principal glucorcorticoid.






15. A rigid structure at the top of the trachea (so it is part of trachea - I assume) made completely out of cartilage. The larynx has three main functions: (1) its rigidness ensures that the trachea is held open (provides an open airway). (2) the epiglo






16. The contribution of an individual gas to the total ppressure of a mixture of gases. Partial pressures are used to describe the amounts of the various gases carried in the bloodstream.






17. A protein channel in a cell membrane that is specific for a particular ion - such as Na+ or K+. Ion channels may be constitutively open (leak channels) - or regulated (voltage - gated or ligand - gated).






18. The 28 days of the menstrual cycle as they apply to the events in the uterus. The endometrial cycle is also known as the uterine cycle - and has the three subphases: menstruation - the proliferative phase - and the secretory phase.






19. The primary androgen (male sex steroid). Testosterone is a steroid hormone produced and secreted by the interstitial cells of the testes. It triggers the development of secondary male sex characteristics during puberty (including spermatogenesis) and






20. A toxin that secreted by a bacterium into its surrounding medium that help the bacterium compete with other species. Some exotoxins cause serious disease in humans (botulism - tetanus - diptheria - toxic shock syndrome).






21. 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.






22. The period of human development from implantation through 8 weeks of gestation. Gastrulation - neurulation - and organogenesis occur during this time period. The developing baby is known as embryo during this time period.






23. All the genetic information in an organism; all of an organism's chromosomes.






24. Bacteria that have a thick peptido glycan cell wall - and no outer membrane. They stain very darkly (purple) in Gram stain.






25. Plasma with the clotting factors removed. Serum is often used in diagnostic tests because it does not clot.






26. A region within the nucleus where rRNA is transribed and ribosomes are partially assembled.






27. A protein - digesting enzyme secreted by the chief cells of the gastric glands. Pepsin is secreted in its inactive form (pepsinogen) and is activated by gastric acid. It is unusual in that its pH optimum is around 1-2; most of these enzymes in the bo






28. Mendels' first law. The Law of Segregation states that the two alleles of a given gene will be separate from one another during gamete formation (meiosis).






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






30. A person with blood type O-. Because this person's red blood cells possess none of the typical blood suface proteins - they cannot initiate an immune reaction in a recipient.






31. A point mutation in which a condon that specifies an amino acid is mutated into a stop (nonsense) codon.






32. The first phase of meiosis I. During prophase I the replicated chromosomes condense - homologous chromsomes pair up - crossing over occurs between homologous chromosomes - the spindle is formed - and the nuclear envelope breaks apart into vesicles. P






33. A hormone made of amino acids (in some cases just a single - modified amino acid). Peptide hormones are generally hydrophilic and cannot cross the plasma membranes of cells - thus receptor for peptide hormones must be found on the cell surface. An ex






34. A chemical released by the axon of a neuron in response to an action potential that binds to receptors on a postsynaptic cell and causes that cell to either depolarize slightlly (EPSP) or hyperpolarize slightly (IPSP). Examples are acetylcholine - no






35. 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






36. A peptide hormone produced and secreted by the alpha cells - of the pancreas. It tartes primarily the liver - stimulating the breakdown of glycogen - thus increasing blood gluocse level.s






37. One of the two small chambers in the heart that receive blood and pass it on to the ventricles. The right atrium receives deoxygenated blood from teh body through the superior and inferiro vena cavae - adn the left atrium receives oxygenated blood fr






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






39. 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.






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






41. A clear fluid the circulates around through the brain and spinal cord that helps to physially support teh brain and act as a shock absorber - and taht also exchanges nutrients and wastes with teh brain and spinal cord.






42. The non - specific uptake of liquid particles into a cell by invagination of the plasma membrane and subsequent 'pinching off' a small bit of the extracellular fluid.






43. A type of synapse at which a chemical (a neurotransmitter) is released from teh axon of a neuron into the ysnaptic cleft where it binds to receptors on the next structure in sequence - either another neuron or an organ.






44. A cyclic version of adenosine monophosphate - where the phosphate is esterified to both the 5' and 3' carbons - forming a ring. Cyclic AMP is an important intracellular signaling moelcule - often called the 'second messenger.' It serves to activate c






45. An enzyme that transcribes RNa. Prokaryotes have a single RNA pol - while eukaryotes have three; in eukaryotes - RNA pol I transcribes rRNA - RNA pol II transcribes mRNA - and RNA pol III transcribes tRNA.






46. The enzyme that breaks down acetylcholine in the synaptic cleft.






47. Movement that is directed by chemical gradients - such as nutrients or toxins. (seen in some bacteria)






48. Molecules made from monosaccharides that serve as the primary source of cellular energy -. Carbohydrates can also act as cell surface markers (good thing to remember).






49. 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.






50. The depolarization of the egg plasma membrane upon fertilization - designed to prevent the entry of more than one sperm into the egg.