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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 the cell membrane at the neuromusclar junction; essentially the postsynaptic membrane at the synapse.






2. The subdivision of the nervous system consisting of the brain and spinal cord.






3. The muscuar layer of the uterus. The myometrium is made of smooth muscles that retains its ability to divide in order to accomodate the massive size increases that occur during pregnancy. The myometrium is stimulated to contract during labor by the h






4. 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.






5. The neurotransmitter used by the sympathetic division of the ANS at the postganglionic (organ - level ) synapse.






6. The prokaryotic ribosome - binding site on mRNA - found 10 nucleotides 5' to the start codon.






7. Plasma with the clotting factors removed. Serum is often used in diagnostic tests because it does not clot.






8. A situation in which the expression of one gene prevents expression of all allelic forms of another gene - e.g. - the gene for male pattern baldness is epistatic to the hair color gene.






9. (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






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






11. The process by which neighboring cells can influence the determination (and subsequent differentiation) of a cell.






12. Pain receptors. Nociceptors are found everywhere in the body except for the brain.






13. Paired masses of lymphatic tissue near the back of the throat that help trap inhaled or swallowed pathogens.






14. The product of glycolysis; 2 pyruvic acid (pyruvate) molecules are produced from a single glucose molecule. In the absence of oxygen - pyruvic acid undergoes fermentation and is reduced to either lactic acid or ethanol; in the presence of oxygen - py






15. One of the four aromatic bases found in DNA and RNA; also a component of ATP - NADH - and FADH2. Adenine is apurine; it pairs with thymine (in DNA) and with uracil (in RNA)






16. 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.






17. The layer of granulosa cells taht surround an oocyte after is has been ovulated.






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






19. One of the two peripheral nervous system supporting (glial) cells. Schwann cells from he myelin sheath on axons of peripheral neurons.






20. A tropic hormone produced by the anterior pituitary gland that targets the thyroid gland - stimulating it to produce and release thyroid hormone.






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






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






23. The valve that regulates the passage of chyme from the stomach into the small intestine.






24. A hormone derived from cholesterol. Steroids are generally hydrophobic and can easily cross the plasma membrane of cells - thus receptors for steroids are found intracellularly. Once this steroid binds to its receptor - the receptor - steroid complex






25. The first substrate in teh Krebs cycle - produced primarily from the oxidation of pyruvate by the pyruvate dehydrogenase complex - however acetyl - CoA is also produced during fatty acid oxidation and protein catabolism.






26. MRna that codes for several different proteins by utliizing different reading frames - nested genets - etc. Polycistronic mRNa is a characteristic of prokaryotes.






27. The energy in a system that can be used to drive chemical reactions. If the change in free energy of a reaction (Delta G - the free energy of the products minus the free energy of the energy of the reactants) is negative - the reaction will occur spo






28. 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).






29. A phase in the cycle between mitosis and S phase (G1) or between S phase and mitosis (G2). During gap phases the cell undergoes normal activity and growth; G1 may include preparation for DNA replication and G2 includes preparation for mitosis. Note t






30. The combination of alleles of an organism carries. In a homozygous genotype - both alleles are the same - whereas in a heterozygous gentorype the alleles are different.






31. The division of the inner cell mass of a blastocyst (developing embryo) into the three primary germ layers. Gastrulation occurs during weeks 2-4 of gestation.






32. Specif ic defense of the body by antibodies - secreted into the blood by B- cells.






33. The white portion of teh tough outer layer of the eyeball






34. An enzyme whose transcription can be stimulated by an abundance of its substrate (as opposed to repressible enzyme). Usually in catabolism.






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






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






37. A point mutation in which a pyrimidine is susbstituted for a pyrimidine - or a purine is substituted for a purine.






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






39. DNA that is densely packed around histones. The genes in heterochromatin are generally inaccessible to enzymes and are turned off.






40. The region of teh brain that coordinates and smooth skeletal muscle activity.






41. A blood clot that forms in an unbrokened blood vessel. Thrombi are dangerous they can break free and begin travelin in the bloodstream (become an embolus). Emboli ultimately become stuck in a small vessel and prevent adequate blood delivery to tissue






42. A thick - transpartent coating rich in glycoproteins that surrounds an oocyte.






43. The loop of the nephron that dips downward into the renal medulla. The loop of Henle sets up a concentration gradient in the kidney such that from the cortex to the renal pelvis osmolarity increases. The descending limb of the loop of Henle is permea






44. A receptor that responds to changes in body position - such as stretch on a tendon - or contraction of a muscle. These receptor allow us to be consciously aware of the position of our body parts.






45. The step in the sliding filament theory during which yosin undergoes a conformaitonal change to its low energy state - in the process dragging the thin filaments (and the attached Z lines) toward the center fo the sarcomere. NOte that power stroke re






46. 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






47. The second most common of the five classes of leukocytes. Lymphocytes are involved in specific immunity and include two cell types - B- cells and T cells. B- cells produce and secrete antibodies and T- cells are invovled in cellular immunity.






48. The amount of energy required to produce the transition state of a chemical reaction. If the activation energy for a reaction is very high - the reaction occurs very slowly. Enzymes (and other catalysts) increase reaction rates by reducing activation






49. The ball of capillaries at the beginning of the nephron where blood filtration takes place.






50. 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