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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 movement of a substance across a membane via pressure. In the kidney - filtration refers specifically to the movement of plasma across the capillary walls fo the glomerulus - into the capsule and tubule of the neprhon. Filtration at teh glomerulu






2. The amount of blood returned to heart by the vena cavae.






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






4. An embryonic structure particularly important in egg - laying animals because it contains the yolk - the only source of nutrients for the embryo developing inside the egg. In humans - the yolk sac is very small (since mammals get their nutrients via






5. A form of genetic recombination in bacteria in which plasmid and/or genomic DNA is transferred from one bacterium to the toher through a conjugation bridge.






6. 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






7. 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.






8. One of several different nutrietns that must be consumed in the diet - and generally not synthesized in the body. Vitamins can be hdyrophobic (fat - solube) or hydrophilic (water - soluble).






9. The division between neighboring cardiac muscle cells. Intercalcated discs include gap junctions - which allow the cells to function as a unit.






10. In skeletal and cardiac muscle tissue - a filament composed of bundles of myosin molecules. The myosin head groups attach to the thick filaments and pull the toward the center of the sarcomere during muscle contraction.






11. The portion of the brain responsible for visual and auditory startle reflexes.






12. A law of population genetics that states that the frequencies of alleles in a given gene pool do not change over time. There are five assumptions required for this law to hold true: there must be no mutation - there must be no migration - there must






13. 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






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






15. A portion of DNA that codes for some product - usually a protein - including all regulatory sequences. Some genes code for rRNA and tRNA - which are not translated.






16. A nonliving - intracellular parasite. Viruses are typically just pieces of nucleic aid surrounded by a protein coat.






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






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






19. A bacterium having a spiral shape (plural = spirochetes)






20. A hormone tha tcontrols the release of another hormone.






21. A bacterial structure formed in unfavorable growth conditions. Endospores have very rough outer shells made of peptidoglycan and can survive harsh conditions. The bacterium inside the endospore is essentially dormant and can become active (called ger






22. The normal configuration of double - stranded DNA in which the 5' end of oen strand is paired with the 3' end of the other






23. The hollow center of an osteon - also known as a Haversian canal. The central canal contains blood vessels - lymphatic vessels - lymphatic vessels - and nerves. Bone is laid down around the central canal in concentric rings called lamellae.






24. The resistance to blood flow in the systemic circulation. Peripheral resistance increases if arteries constrict (diameter decreases) - and an increase in peripheral resistance leads t o an increase in blood pressure.






25. Hardy crystals consisting of calcium and phosphate that form the bone matrix.






26. The fourth and final phase of meiosis II. Telophase II is identical to mitotic telophase - except that the number of chromosomes was reduced by half during meiosis. I.






27. 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.






28. The sphincter that separates the final part of the small intestine (the ileum) from the fron part of the large intestine (the cecum). It is typically kept contracted (closed) so that chyme can remain in the small intestine as long as possible. The il






29. The valve that controls the release of feces from the recturm. It has an internal part made of smooth muscle (thus involuntary) and an external part made of skeletal muscle (thus voluntary).






30. Bacteria that have a thin peptidoglycan cell wall covered by an outer plasma membrane. They stain very lightly (pink) in Gram stain. Gram - negative bacteria are typically more resistant to antibiotics than Gram - positive bacteria.






31. A neuron with a single axon and multiple dendrites; the most common type of neuron in the nervous system.






32. The force required to resist the movement of water by osmosis. Osmotic pressure is essentialy a measure of the concentration of a solution. A solution that is hyighly concnetrated has a strong tendency to draw water into itself - so the pressure requ






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






34. The interior of a mitochondrion (the region bounded by the inner membrane). - The matrix is the site of action of pyruvate dehydroganse complex and the Krebs cycle.






35. The organ that carries out teh command sent along a particular motor neuron






36. (1) The integration of input (EPSPs and IPSPs) from many presynaptic neruons by a single postsynaptic neuron - either temporaly or spatially. Summation of al input can either stimulate the postsynaptic neuron and possibly lead to an action potential






37. Peptidyl - tRNA site; the stie on a ribosome where the growing peptide (attached to a tRNA) is found during translation.






38. The release of milk from the mammary glands via contraction of ducts within the glands. Contraction is stimulated by oxytocin - which is released from the posterior pituitary when the baby begins nursing.






39. The phase of the cell cycle during which the genome is replicated.






40. (1) The secretion of useful substances from a cell - either into the blood (endocrine secretin) or into a cavity or onto the body surface (exocrine secretion). (2) in the nephron - the movement of substances from the blood to the filtrate along the t






41. A fibrous protein found on the intracellular side of the plasma membrane (also associated with the Golgi complex) that helps invaginate the membrane. Typically cel surface receptors are associated with clathrin - coated pits at the plasma membrane bi






42. Early embryonic ducts that can develop into male internal genitalia under the proper stimulation (testosterone).






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






44. The smallest (and final) fibers in the cardiac conduction system. The Purkinje fibers transmit the cardiac impulse to the ventricular muscle.






45. An organism that will use oxygen (aerobic metabolism) if it is available - and that can ferment (anaerobic metabolism) if it is not.






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






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






48. 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






49. The monomer of a protein; amino acids hae an amio group on one end fo the molecule and a carboxylic acid group on the other - and of the of 2 different side chains.






50. A layer of connective tissue underneath the epidermis of the skin. The dermis contains blood vessels - lymphatic vessels - nerves - sensory receptors - and glands.