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






2. An integral membrane protein that undergoes a conformational change to move a molecule from one side of the membrane to another. See also 'uniporter' - 'antiporter' - and 'symporter'.






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






4. A pathway through a plasma membrane that restrics passage based only on the size of the molecules. Pore are made from porin proteins.






5. The duplication of DNA






6. A mechanism for increasing tension (contractile length) in a muscle by activating more motor units.






7. A self - initiating action potential that occurs in the conduction system of the heart and triggers action potentials (and thus contraction) in the cardiac muscle cells Tee pacemaker potential is triggered by the regular - spontaneous depolarization






8. A pair of replicated homologous chromosomes. Tetrads form during prophase I of meiosis so that homologous chromosomes can exchange DNA in a process known as 'crossing over.'






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






10. A precursor cell that undergoes mitosis during fetal development to produce more oogonium. These cells are then activated to produce primary oocytes - which remain dormant until stimulated to undergo meiosis I during some future menstrual cycle.






11. A four - subunit protein found in red blood cells that binds oxygen. Each subunit contains a heme group - a large multi - ring molecule with an iron atom at its center. One hemoglobin molecule can bind four oxygen molecules in a cooperative manner.






12. Also called occluding junctions - tight junctions form a seal between cells that prevents the movement of substances across the cell layer - except by diffusion through the cell membranes themselves. Tight junctions are found between the epithelial c






13. The clear portion of the tough outer layer of teh eye ball - found over the iris and pupil






14. 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






15. Muscles that help focus light on teh retin by controlling the curvature of the lens of the eye.






16. 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).






17. The percentage of wholeblood made up of erythrocytes The typical hematocrit value is between 40-45%.






18. Very small air tubes int eh respiratory system (diameter 0.5 - 1.0 mm). The walls of the bronchioles are made of smooth muscle (thus involunatry) to help regulate air flow.






19. The allele in a heterozygous genotype that is expressed; the phenotype resulting from either a heterozygous genotype or a homozygous dominant genotype.






20. The inner epithelial lining of the uterus that thickens and develops during the menstrual cycle - into which a fertilized ovum can implant - and which sloughs off during menstration if a pregnancy does not occur.






21. Toward the 3' end of an RNA transcript (the 3' end of the DNA coding strand). Stop codons and (in eukaryotes) the pol - A tail are found 'downstream.'






22. The specialized cells of the heart that spontaneously initiate action potentials and transmit them to the cardiac muscle cells. The cells of the conduction system are essentially cardiac muscle cells - but lack the contractile fibers of the muscle ce






23. Diploid cells resultinf rom the activation of a spermatogoium; primary spermatocytes are ready to enter meiosis I. remember: cyte means ready to undergo meiosis.






24. The oxidation of high - energy electron carriers (NADH and FADH2) coupled to the phosphorylation of ADP - producing ATP. In eukaryotes - oxidative phosphorylation occurs in the mitochondira.






25. A lipid bilayer that surrounds the capsid of an animal virus. the envelope is acquired as teh virus buds out through the plasma membrane of its host cell. Not all annimal viruses possess and envelope.






26. A small cell with extremely little cytoplasm that results from the unequal cytoplasmic divsion of the primary (produces the first polar body) and the secondary (produces the second polary body) oocytes during meiosis (oogenesis). The polar bodies deg






27. One of the four aromatic bases found in DNA and RNA. Cytosine is a pyrimidine; it pairs with guanine.






28. The nerve extending from the back of teh eyeball to teh brain that carries visual information. The ptic nerve is made up of the axons of the ganglion cells of the retina.






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






30. A situation in which a heterozygot displays a blended version of the pheotypes associated with each allele - e.g. pure - breeding white - flowered plants crossed with pure - breeding red - flowered plants produces heterozygous offspring plants with p






31. The portion of the hindbrain that controls respiratory and blood pressure - and specialized digestive and respiratory functions such as vomiting - sneezing - and coughing.






32. The neurotransmitter used throughout the parasympathetic nervous system as well as the neuromuscular junction.






33. A waste product of protein dbreakdown - produced by the liver and relased into the bloodstream to be eliminated by the kidney.






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






35. Oil - forming glands found all over the body - especially on the face and neck. The product (sebum) is released to the skin surface through hair follicles.






36. The folds of skin that enclose the vaginal and urethral openings of females.






37. A protein that is associated with the plasma membrane of a cell - but that is not embedded in the lipid bilayer. Peripheral proteins typically associate with embedded proteins through hydrogen bonding or electrostatic interactions.






38. A type of lymphocyte that can recognize (bind to) an antigen adn secrete an antibody specific for that antigen. When activated by binding an antigen - B cells mature into plasma cells (that secreted antibody) and memory cells (that patrol the body fo






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






40. A skeletal muscle cell - also known as a muscle fiber. Skeletal muscle cells are formed from the fusion of many smaller cells (during development) consequently they are very long and are multinucleate.






41. A form of evolution in which the same organism is placed into different environments with different selection pressures. This causes organisms to evolve differently - to diverge from their common ancestor. The resulting (new) species may share struct






42. The third phase of the ovarian cycle - during which a corpus luteum is formed from the remnants of the follicle that has ovulated its oocyte. The corpus luteum secretes progestrone and estrogen during this time period - which typically lasts from day






43. The outer layer of an organ - e.g. the renal cortex - the ovarian cortex - the adrenal cortex - etc.






44. A localized change in a neruon's or musce cell's membrane potential that can propogate itself away from its point of origin. Action potentials are an all - or - none process mediated by the opening of voltage - gated Na+ and K+ channels when the memb






45. The rapid mitotic division of a zygot that being within 24-36 hours after fertilization






46. The fusion of a sperm with an ovum during sexual reproduction. Fertilization typically occurs in the uterine tubes and requires capacitation of the sperm and relase of the acrosomal enzymes. Fertilization is a species - specific process - requiring b






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






48. Muscles located in between the ribs that play a role in ventilation.






49. A layer of collagen fibers that separates epithelial tissue from connective tisse (example of epithelial cells in digestive tract) - they are actual connective tissue.






50. The depolarization of the egg plasma membrane upon fertilization - designed to prevent the entry of more than one sperm into the egg.