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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. A neuron found completely within the central nervous system. Interneous typically connect sensory and motor neurons - especially in reflex arcs.






2. The primary enzyme in peroxisomes; catalse catalyzes the hydrolysis of hydrogen peroxide (H2O2) into water and oxygen.






3. A molecule (usually a protein) capable of initiating an immune repsonse (antibody production).






4. A haploid but immature cell resulting from the second meiotic division f spermatogenesis. Spermatids undergo significant physical changes to become mature sperm (spermatozoa).






5. An enzyme secreted by the juxtaglomerular cells when blood pressure decreases. Renin onverts angiotensinogen to angiotensin I.






6. Toward the 5' end of an Rna transcript (the 5' end of the DNA coding strand). The promoter and start sites are upstream.






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






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






9. The principal glucocorticoid secreted from teh adrenal cortex. This steroid hormone is released ruing stress - causing increased blood glucose levels and reducing inflammation. The latter effect has led to a clinical use of cortisol as an anti - infl






10. A version of a gene. For example - the gene may be for eye color - and the allels include those for brown eyes - those for blu e eyes - those green eyes - etc. At most - dploid organsims can posses only two alleles for a given gene - one on each of t






11. An enzyme inhibitor that binds at a site other than the active sit of an enzyme (binds at an allosteric site). THis changes the three - dimensional shape of the enzyme such that it can no longer catalyze the reaction






12. 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






13. The maintenance of relatively constant internal conditions (such as temperature - pressure - ion balance - pH - etc.) regardless of external conditions.






14. The second most common of the five classes of leukocytes. Lymphocytes are involved in specific immunity and include two cell types - B- cells and T cells. B- cells produce and secrete antibodies and T- cells are invovled in cellular immunity.






15. One of the four aromatic bases found in DNA. Thymine is a pyrimidine; it pairs with adenine.






16. 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






17. A structure composed of a ring of nine microtube triplets - found in pairs in the MTOC (microtubule organizing center) of a cell. The centrioles duplicate during the cell division - and serve as the organizing center for the mitotic spindle.






18. Gaps in the myelin sheath of the axons of peripheral neruons. Action potentials can 'hump' from node to node - thus increasing the speed of conduction (saltatory conduction).






19. Something that works together with another thing to augment the the second thing's activity. For example - a uscle that assists another muslce is said to be a syngergist. An enzyme that helps another enzyme is a synergist.






20. The failure of homologous chromosomes or sister chromatids to separate properly during cell division. This could ocur during anaphase I of meiosis (homologous chromosomes) [--> leaving 2 gametes w/ 2 copies and 2 gametes w/ no copies of chromosome] -






21. A protein hormone secreted by sustenacular cells of the testes that acts to inhibit the release of FSH and LH from the anterior pituitary.






22. A gene appearing in a single copy in diploid organisms - e.g. X- linked genes in human males.






23. The process of breaking down large molecules into smaller precursors - e.g. digesion of starch into glucose.






24. The specific site on an antigenic molecule that binds to a T cell receptor or to an antibody.






25. An organism that can only survive in the absence of oxygen (anaerobic metabolism); oxygen is toxic to obligate anaerobes.






26. The birth canal; the stretchy - muscular passageway through which a baby exits the uterus during childbirth.






27. Aromatic bases found in DNa and RNA that have a single - ring structure. They include cytosine - thymine - and uracil.






28. The secon phase of mitosis. During metaphase chromosomes align at the center of the ell (the metaphase plate).






29. Pain receptors. Nociceptors are found everywhere in the body except for the brain.






30. 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






31. Also called negative feedback - the inhibition of an early step in a series of events by the product of a later step in the series. This has the effect of stopping the series of events when the products are plentiful and the series is unnecesseary. F






32. 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.






33. Sensory receptors found in the inner ear. Cochlear hair cells respond to vibration in the cochlea caused by sound waves and vestibular hair cells respond to changes in position and acceleration (used for balance).






34. The first branches of the trachea. There are two primary bronchi - one for each lung.






35. A protein - based substance secreted by cells of the epiderms as they migrate outward. The keratin makes the cells tougher (better able to withstand abrasion) and helps make the skin waterproof.






36. A hole in the center of the iris of the eye that allows light to enter the eyeball. The diameter of pupil is controlled by the iris in response to the brightness of the light.






37. Myelinated axons






38. The portion of theforebrain that includes the thalamus and hypothalamus.






39. The function unit of the kidney. Each kidney has about a million nehprons; this is where blood filtration and subsequent modification of the filtrate occurs. The nephron empties into collecting ducts - which empty into the ureter.






40. 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.






41. Diploid cells resulting from the activation of anoogoium; primary oocytes are ready to enter meiosis I. remember: cyte means ready to undergo meiosi






42. Very small tube or channel - such as is found between lacunae (connecting them together) in compact bone.






43. An enzyme whose transcription can be stimulated by an abundance of its substrate (as opposed to repressible enzyme). Usually in catabolism.






44. The outer layer of smooth muscle in the wall of the digestive tract. When the longitudinal muscle contracts the tube shortens.






45. Earlier embryonic ducts that can develop into femal internal genitalia in the absence of testosteron.






46. An **organic molecuel taht associates non - covalently with an enzyme - and that is required for the proper functioning of the enzyme.






47. The period of time following an action potential when it is possible - but difficult - for the neuron to fire a second action potential due to the fact that membrane is further from theshold potential (hyperpolarized).






48. The maximal volume of air that the lungs can contain. Total lung capacity is the sum of the vital capacity and the residual volume - and is typically about 6000 mL (6L).






49. 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.






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