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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 digests starch into disaccharides. Amylase is secreted by salivary glands and by the pancreas.






2. The specific location on a DNa strand where replication begins.. Prokaryotes typically have a single origin of replication - while eukaryotes have several per chromosome.






3. A structure composed of a ribose molecule linked to one of the aromatic bases. In a deoxynucleoside - the ribose is replaced with deoxyribose.






4. A kinase in smooth muscle cells activated by calmodulin the presence of Ca2+. As its name implies - this kinase phosphorylates myosin - activating it so that muscle contraction can occur.






5. The amount of energy required to produce the transition state of a chemical reaction. If the activation energy for a reaction is very high - the reaction occurs very slowly. Enzymes (and other catalysts) increase reaction rates by reducing activation






6. Inhibitory postsynaptic potential; a slight hyperpolarization of the postysynaptic cell - moving the membrane potential of that cell further from threshold.






7. 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






8. The first substrate in teh Krebs cycle - produced primarily from the oxidation of pyruvate by the pyruvate dehydrogenase complex - however acetyl - CoA is also produced during fatty acid oxidation and protein catabolism.






9. (singular alveolus.) Tiny sacs - with walls only a single cell layer thick found at the end of the respiratory bronchiole tree. Alveoli are the site of gas exchange in the respiratory system.






10. In the autonomic divison of the PNS - a neuron that has its cell body located in the CNS - and whose axon extends into the PNS to synapse with a second neuron at an autonoic ganglion. (The second neuron's axon synapses with the target axon)






11. The majority of the cells surrouding an oocyte in a follicle. Granulosa cells secrete estrogen during the follicular phase of the ovarian cycle (before ovulation).






12. An organism that cannot make its own food - and thus must ingest other organisms.






13. A structure composed of two coils of DNA wrapped around an octet of histone proteins. The nucleosome is the primary form of packagin of eukaryotic DNA.






14. 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).






15. Specialized lymphatic capillaries in the intestines that take up lipids as well as lymph.






16. A nucleotide sequence that intervenes between protein - coding sequences. In DNA - these intervening sequences typically contain **regulatory sequences - however - in RNA they are simply spliced out to form the mature (translated) transcript.






17. The inside of the a hollow organ (e.g. - the somach - intestines - bladder - etc.) or a tube (e.g. - blood vessels - ureters - etc.)






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






19. The first step in viral infection. Attachemen of a virus to its host is very specific and is also known as adsorption.






20. A method of DNA protection utilized by prokaryotes in which their large circular chromosome is coiled upon itself.






21. The division of the peripheral nervous system that innervates and controls the skeletal muscles; also known as the voluntary nervous system.






22. Also called simply - 'islet cells' these are the endocrine cells of the pancreas. Different cell types wihtin the inslets secrete insulin - glucagon - and somatostatin






23. A hormone secreted by the samll intestine (duodenum) in response to the presence of fats. It promotes release of bile from the gallbladder and pancreatic juice from the pancreas - and reduces stomach motility.






24. One of the three primary (embryonic) germ layers formed during gastrulation. Ectoderm ultimately forms external structures such as the skin - hair - nails - and inner linings of the mouth and anus - as well as the entire nervous system.






25. An intracellular chemical signal (such as cAMP ) that relays instructions from the cell surface to enzymes in the cytosol.






26. A bacterium having a rod - like shaped (plural = bacilli).






27. 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.






28. The volume of blood pumped out the heart in a single contraction.






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






30. A hormone produced by the C- cells of the thyroid gland that decreases serum calcium levels. It targets teh bones (stimulates osteoblasts) - the kidneys (reduces calcium reabsorption) - and the small intestine (decreases calcium absorption).






31. The band of the sarcomere that extends the full length of the thick filament. The A band includes regions of thick and thin filament overlap - as well as a region of thick filament only. A bands alternate with I bands to give skeletal and cardiac mus






32. The capillaries that surround the tubules of the nephron. The vasa recta reclaims reabsorbed substances - such as water and sodium ions.






33. A single piece of double - stranded DNA; part of the genome of an organism. Prokaryotes have circular chromosomes and eukaryotes have linear chromosomes.






34. A bacterium that cannon survive on minimal medium (glucose alone) because it lacks the ability to syntheisze a molecule it needs to live (typically an amino acid). Auxotrphs must ave the needed substance (the auxiliary trophic substance) added to the






35. A long - coiled duct on the outside of the testis in which sperm mature.






36. The division of the inner cell mass of a blastocyst (developing embryo) into the three primary germ layers. Gastrulation occurs during weeks 2-4 of gestation.






37. A protein embedded in the lipid bilayer of a cell. These are typicallly cell surface receptors - channels - or pumps.






38. The innermost layer of the eyeball. The retina is made up of a layer of photoreceptors - a layer of bipolar cells - and a layer of ganglion cells.






39. The removal ( and usually the activation) of a viral genome from its host's genome.






40. Photoreceptors in the retina of the eye that responds to bright light and provide color vision.






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






42. A fluid - filled sphere formed about 5 days after fertilization of an ovum that is made up of an outer ring of cells and inner cell mass. THis is the structure that implants in the endometrium of the uterus.






43. A tropic hormone produced by the anterior pituitary gland that targets the gonads. In females - FSH stimulates the ovaries to develop follicles (oogenesis) and secrete estrogen; in males - FSH stimulates spermatogenesis.






44. The cells of the distal tubule at the juxtaglomerular apparatus. They are receptors that monitor filtrate osmolarity as a means of regulatin filtration rate. If a drop is osmolarity is sensed - the macula densa dilates the afferent arteriole (to incr






45. A carrier protein that transports two molecules acrss the plasma membrane in opposite directions.






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






47. A virus with an RNA genome (e.g. HIV) that undergoes a lysogenic life cycle in a host with a double stranded DNA genome. In order to integrate its genome with the host cell genome - the virus must first reverse trasncribe its RNA genome to DNA.






48. Paired glands near the posterior side of the vaginal that secrete an alkaline mucus upon sexual arousal. The mucus helps to reduce the acidity of the vagina (which could be harmful to sperm) and lubricates the vagina to facilitate penetration.






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






50. A normal blood protein produced by the liver - angiotensin is converted to angiotensim I by renin (secreted by kidney when blood pressur falls). Angiotensin I si further onverted to angiotensim II by ACE (angiotensin converting enzyme). Angiotensin I