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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. 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






2. 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.






3. An electrical potential established across the plasma membrane of all cells by the Na+/K+ ATPase and the K+ leak channels. In most cells - the resting membrane potential is approximately -70 mV with respect to the outside of the cell.






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






5. 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.






6. A protein found in the plasma membrane of all cells in the body that uses the energy of an ATP (hydrolyzes ATP) to move three Na+ ions out of the cell and two K+ ions into the cell - thus establishing concentrations gradients for these ions across th






7. A neuron that carries information (action potentials) away from the central nervous system; a motor neuron.






8. 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.






9. An enzyme inhibitor that competes with substrate for binding at the active site of teh enzyme. When the inhibitor is bound - no product can be made.






10. The tubes that carry urine from the kindeys to the bladder.






11. A form of evolution in which different organisms are placed into the same environment and exposed to teh same selection pressures. This causes the organisms to evolve along similar lines. As a result - they may share functional - but not structural s






12. The entropy (disorder) of the universe (or system) tends to increase.






13. 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.






14. 'Yellow body.' The remnants of an ovarian follicle after ovulation has occurred. The cells enlarge and begin secreting progesterone - the dominant female hormone during the second half of the menstrual cycle. Some estrogen is also secreted.






15. A type of lipoprotein; the form in which absorbed fats from the intestines are transported to the circulatory system.






16. 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






17. The structure in the cochlea of the inner ear made up of the basilar membrane - the auditory hair cells - and the tectorial membrane. The Organ of Corti is the site where auditory sensation is detected and transduced to action potentials.






18. A group of nucleotides that does not specify a particular amino acid - but instead serves to notify the ribosome that the protein being translated is complete. The stop codons are UAA - UGA - and UAG. They are also known as nonsense codons.






19. The formation of haploid gametes (sperm or ova) via meiosis.






20. Muscle tissue found in the walls of hollow organs - e.g. - blood vessels - the digestive tract - the uterus - etc. Smooth muscle is non - striated - uninucleate - and under involuntary control (controlled by the autonomic nervous system).






21. A flexible piece of cartilage in the larynx that flips downward to seal teh trachea during swallowing.






22. The portion of the cell membrane at the neuromusclar junction; essentially the postsynaptic membrane at the synapse.






23. A contact point between the afferent arteriole of the glomerulus and the distal convoluted tubule of the nephron. It is involved in regulating blood pressure.






24. 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






25. 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






26. 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).






27. The main duct of the pancreas. The pancreatic duct carries the exocrine secretions of the pancreas (enzymes and bicarbonate) to the small intestine (dueodenum).






28. Molecules made by connecting amino acids via peptide bonds. Proteins are synthesized (translated) by ribosomes - and function as enzymes - carriers - structrual fibers - cell surface receptors - channels - porters - hormones - etc.






29. A form of symbiosis in Which both organisms involved benefit from the association.






30. The outer ring of cells of a blastocyst. The trophoblast takes part in the formation of the placenta.






31. 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.






32. The portion of the nephron tubule after the loop of Henle - but before teh collecting duct. Selective reabsorption and secretion occur here - most notably regulated reabsorption of water and sodium.






33. An amphipathic molecule secreted by cells in the alveoli (type 2 alveolar cells) tha reducs surface tension on the inside of the alveolar walls. This prevents the alveoli from collapsing upon exhale and sticking together - thus reducing the effort re






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






35. DNA replication in which each of the parental strands is read to make a complementary daughter strand - ethus each new DNa molecule is composed of half the parental molecule paired with a newly synthesized strand.






36. The smooth ER of a muscle cell - enlarged and specialized to act as a Ca2+ reservoir. The SR winds around each myofibril in the muscle cell.






37. The synapse between a motor neuron and a muscle cell. At the NMJ - the muscle cel lmembrane is invaginated and the axon terminus is elongated so that a greater area of membrane can be depolarized at one time.






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






39. 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.






40. In the autonomic division of the PNS - a neuron that has its cell body located in the autonomic ganglion (where a preganglionic neuron synapses with it) and whose axon synapses with the target axon.






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






42. 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






43. A complex polymer of sugars and amino acids; the substance From which bacterial ell walls are made.






44. Identical copies of a chromosome - produced during DNA replication and held together at the centromere Sister chromatids are separated during anaphase of mitosis.






45. A triat determined by a gen on either the X or Y chromosomes (the sex chromosomes).






46. Haploid cells resulting from the first meiotic division of spermatogenesis. Secondary spermatocytes are ready to enter meiosis II.






47. Small cavities in the bone or cartilage that hold individual bones or cartilage cells.






48. A small gland encircling the male urethra just inferior to the bladder (only reproductive structure not paired). Its secretion contain nutrients and enzymes and account for approximately 35% of the ejaculate volume.






49. 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).






50. An organelle surrounded by a double=membrane (two lipid bilayers) where ATP production takes place. The interior (matrix) is where PDC and the Krebs cycle occur - and the inner membrane contains the enzymes of the electron trasport chain and ATP synt