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






2. The duplication of DNA






3. (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.






4. The primary muscle of inspiration. The diaphragm is stimulated to contract at regular intervals by the respiratory center in the medulla oblongata (via the phrenic nerve). Although it is made of skeletal muscle (and can therefore be voluntary control






5. 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.






6. The division of the autonomic nervous system known as the 'fright or flight' system. It causes a genera increase in body activities such as heart rate - respiratory rate - and blood pressure - and an increase in blood flow to skeleltal muscle. It cau






7. The synthesis of blood cells (occurs in the red bone marrow)






8. The RF value - the percentage of recombinant offspring resulting from a given genetic cross. The recombination frequency is proportional to the physical distance between genes on a chromosome. If a recombination frequency is low - the genes under con






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






10. The region at the center of an A band of a sarcomere that is made up of myosin only. The H zone gets shorter (and may disappear) during muscle contraction.






11. The 28 days of the menstrual cycle as they apply to events in the ovary. The ovarian cycle has three subphases: the follicular phase - ovulation - and the luteal phase.






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






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






14. 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






15. 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






16. A non - protein - but organic - molecule (such as vitamin) that is covalently bound to an enzyme as part of the active site.






17. A cyoplasmic Ca2+- binding protein. Calmodulin is particularly important in smooth muscle cells - where binding of Ca2+ allows calmodulin to activate myosin light - chian kinase - the first step in smooth muscle cell contraction.






18. A group of three enzymes that decarboxylates pyruvate - creating an acetyl group and carbon dioxide. The acetyl group is then attached to coenzyme A to produce acetyl - CoA - a substrate in the Krebs cycle. In the process - NAD+ is reduced to NADH. T






19. Globular protein that assist in DNA packaging in eukaryotes. Histones form octamers around which DNA is wound to form a nucleosome.






20. A type of syanpse in which the cells are connected by gap junctions - allowing ions (and therefore an action potential) to spread easily from cell to cell - usually in smooth and cardiac muscle. - compared to chemical synapse.






21. A chromosome that does not determine gender (is not a sex chromosome). Humans have two sex chromsomes and 22 autosomes.






22. The movement of a hydrophobic molecule across the plasma membrane of cell - down its concentration gradient. Since the molecule can esialy interact with the lipid bilayer - no additional help (such as a channel or pore) is required.






23. An enzyme that phosphorylates something else. Kinases are frequently used in regulatory pathways - phosphorylating other enzymes.






24. A thick muscular tube that connects the epididymis of the testes to the urethra. Muscular contractions of the vas deferns during ejaculation ehp propel the sperm outward. Severing of the vas deferens (vasectomy) results in sterility of the male.






25. A point mutation in which a codon that specifies an amino acid is mutated into a new codon that specifies the same amion acid.






26. Also called immunoblobins - the antibodies are protiens secreted by B- cells upon activation that bind in a highly specific manner to foreign proteins (such as those found of the surface of pathogens or transplanted tissues). The foreign proteins are






27. Extremely small pseudo - cells in the blood - important for clotting. They are not true cells - but are broken - off bits of a larger cell (a megakaryocyte).






28. A drop in blood pH due to hypoventilation (too little breathing) and a resulting accumulation of Co2.






29. 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)






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






31. A thin (4 mm) layer of gray matter on the surface of the cerebral hemispheres. The cerebral cortex is the conscious mind - and is functionally divided into four pairs of lobes: the frontal lobes - the parietal lobes - the temporal lobes - and the occ






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






33. 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






34. 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






35. The final portion of the large intestine.






36. An ion channel that is opened or closed based on the binding of a specific ligand to teh channel. Once opened - the channel allows the ion to cross the plasma membrane according to its concentration gradient. An examples is the acetylcholine receptor






37. The unit of muscle contraction. Sarcomeres are bounded by Z lins - to which thin filaments attach. Thick filaments are found in the center of the sarcomere - overlapped by thin filaments over one another during contraction reduces the distance betwee






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






39. The main protease secreted by the pancreas; trypsin is activated (from trypsinogen) by enterokinase - and subsequently activates other pancreatic enzymes.






40. A subphase of male orgasm. Emission is the movement of sperm (via the vas deferens) and semen into the urtehra in prepartion for ejaculation.






41. Proteins that bind to and stabilize the signle strands of DNA exposed when helicase unwinds the double helix in preparation for replication.






42. 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] -






43. A hormone released by the anterior pituitary that targets all cells in the body. Growth hormone stimulates whole body growth in children and adolescents - adn increases cell turnover rate in adults.






44. Transfer RNA; the type of RNA that carries an amino acid from the cytoplasm to the ribosome for incorporation into a growing protein.






45. 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






46. A generic connective tissue cell that produces fibers; the progenitor of all other connective tissue cell types.






47. The movement of a particle (the solute) in a solution from its region of high concentration to its region of low concentration ( or down it concentration gradient).






48. The flow of blood from the heart - through the lungs - and back to the heart.






49. The fraction of teh end - diastolic volume ejected from the ventricles in a single contraction of teh heart. THe ejection fraction is normally around 60% of the end diastolic volume.






50. Connective tissue that lacks great amount of collagen or elastic fibers (hence - loose) - e.g. - adipose tissue and areolar (general connective) tissue.







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