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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. Movement across the membrane of a cell that does not require energy input from the cell. Passive transport relies on concentration gradients to provie the driving force for movement - and includes both simple and facilitated diffusion.






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






3. 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.






4. The stoppage of bleeding; blood clotting.






5. A neuron - to - neuron - neuron - to - organ - or muscle to cell - to - muscle cell junction.






6. 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.






7. 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.






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






9. The site(s) where the parental DNA double helix unwinds during replication.






10. An X- linked recessive disorder in Which blood fails to clot properly - leading to excessive bleeding if injured.






11. Very small tube or channel - such as is found between lacunae (connecting them together) in compact bone.






12. An integral protein that selectively allows molecules across the plasma membrane. See also entries under 'ion channel' - 'voltage - gated channel' - and 'ligand - gated channel'.






13. 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






14. The blood vessel that carries deoxygenated from the right ventricle of the heart to the lungs.






15. The first phase of the ovarian cycle - during which a follicle (an oocyte and its surroudning cells) enlarges and matures. This phase is under the control of FSH from the anterior pituitary - and typically lasts from day 1 to day 14 of the menstrual






16. The elimination of wastes from the body.






17. A cell surface receptor associated with an intracellular protein that binds and hydrolyzes GTP. When GTP is bound - the protein is active - and can regulate the activity of adenylyl cyclease; this modifies the intracellular levels of second messenger






18. A normal component of the outer membrane of Gram - negative bacteria. Endotoxins produce extreme immune reactions (septic shock) - particularly when many of them enter the circulation at once.






19. A blood vessel that carries blood toward the heart chambers. Veins do not have muscular walls - have valves to ensure that blood flows in one direction only - and are typically low - pressure vessels.






20. The period of time during which the ventricles of the heart are contracted.






21. The sum of all genetic material in a population.






22. The perio of time during which the ventricles of the heart are relaxed.






23. A solid clump of cells resulting from cleavage in the early embryo. Because there is very little growth of these cells during cleavage - the morula is ony about as large as the original zygote.






24. A structure made of two protein subunits and rRNA; this is the site of protein synthessis (translation) in a cell. Prokaryotic ribosomes (also known as 70S ribosomes) are smaller than eukaryotic ribosome (80S ribosomes). The S value refers to the sed






25. The enzyme that catalyzes the phosphorylation of fructose -6- phosphate to form fructose -1-6- bisphosphate in the third step of glycolysis. This is the main regulatory step of glycolysis. PFK is feedback - inhibited by ATP.






26. A point mutation in which a condon that specifies an amino acid is mutated into a stop (nonsense) codon.






27. An insulating layer of membranes wrapped around the axons of almost all neurons in the body. Myelin is essentially the plasma membranes of specialized cells; Schwann cells in the peripheral nervous system - and oligodendrocytes in the central nervous






28. The mechanism described by Charles Darwin that drives evolution. Through mutation - some organisms possess genes that make them better adapted to their environment. These organisms survive and reproduce more than those that do not possess the benefic






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






30. The process of bulidng complex structures out of simpler precursors - e.g. synthesizing protiens from amino acids.






31. The non - specific uptake of liquid particles into a cell by invagination of the plasma membrane and subsequent 'pinching off' a small bit of the extracellular fluid.






32. Chemoreceptors on the tongue that respond to chemicals in a food.






33. 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.'






34. Messenger RNA; the type of RNa that is read by a ribosome to synthesize protein.






35. A chemical released by the axon of a neuron in response to an action potential that binds to receptors on a postsynaptic cell and causes that cell to either depolarize slightlly (EPSP) or hyperpolarize slightly (IPSP). Examples are acetylcholine - no






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






37. The small artery that carries blood toward the capillaries of the glomerulus.






38. Something that works together with another thing to augment the the second thing's activity. For example - a uscle that assists another muslce is said to be a syngergist. An enzyme that helps another enzyme is a synergist.






39. A blood protein essential to blood clotting. The conversion of fibrinogen to its active form (fibrin) is among the final steps in clot formation - and is triggered by thrombin.






40. The layer of ciliated - mucus - covered cells in the respiratory tract.The cilia continually beat - sweeping contaminated mucus upward toward the pharynx.






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






42. The physical characterisitcs resulting from the genotype. Phenotypes are usually described as dominant or recessive.






43. A region of specialized cardiac muscle cells in the right atrium of the heart that initiate the impules of heart contraction; for this reason the SA node is knownas the 'pacemaker' of the heart.






44. A globular protein that ssociated with tropomyosin as part of the thin filament of the sarcomere. Troponin binds Ca2+ - which causes the conformaiton change in tropomyosin required to expose the myosin - binding sites on actin and initiate muscle con






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






46. A pigmented membrane found just in from the lens of the eye. In the center of iris is the pupil - a hole through which light enters the eyeball. The iris regulates the diameter of the pupil in response to the brightness of light.






47. The largest organ in the abdominal cavity. The liver has many roles - including procesing of carbohydrates and fats - synthesis of urea - production of blood proteins - production of bile - recycling heme - and storage of vitamins.






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






49. A peptide hormone produced and secreted by the Beta cells of the pancreas. Insulin targets cells in the body - especially the liver and muscle - and allows them to take glucose out of gthe blood (thus lowering blood glucose levels).






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