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






2. 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).






3. A cytoplasmic protein that binds to a stop codon where it appears in the A- site of the ribosome. Release factors modify the peptidyl transferase activity of the ribosome - such that a water molecule is added to the end of the completed protein. This






4. A sac filled with fluid (aminotic fluid) that surroudns and protects a developing embryo.






5. 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).






6. Pepsinogen - secreting cells foudn at teh bottom of the gastric glands






7. A subsequent immune response to previously encountered antigen that results in antibody production and T cell activation. The secondary immune response is mediated by memory cells (produced during the primary immune respone) and is much faster and st






8. An abdominal organ that is considered part of the immune system. THe spleen has four functions: (1) it filters antigen from the blood (2) it is the site of B cell maturation - (3) it stors blood - and (4) it destroys old red blood cells.






9. Extremely small pseudo - cells in the blood - important for clotting. They are not true cells - but are broken - off bits of a larger cell (a megakaryocyte).






10. 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.'






11. The phase of the cell cycle during which the replicated genome is divided. Mitosis has four phases (prophase - metaphase - anaphase - telophase) and includes cytokinesis (the physical splitting of the cell into two new cells).






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






13. The 3D site of an enzyme where substrates (reactants) bind and a chemical reaction is facilitated.






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






15. 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






16. 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.






17. A string of several hundred adenine nucletodies added to the 3' end of the eukaryotic mRNA.






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






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






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






21. An ion channel that is opened or closed based on the binding of a specific ligand to teh channel. Once opened - the channel allows the ion to cross the plasma membrane according to its concentration gradient. An examples is the acetylcholine receptor






22. A statistical rule stating that the probability of two independent events occuring together is the product of their individual probabilities.






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 removal ( and usually the activation) of a viral genome from its host's genome.






25. One of several vessels that carry oxygenated blood from the lungs to the left atrium of the heart.






26. 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.






27. The first (approximately 5%) of the small intestinte.






28. An enzyme whose transcription can be stopped by an abundance of its product (as opposed to inducible enzymes). Usually part of anabolism of product.






29. A situation in which a heterozygote displays the phenotype associated with each of the alleles - e.g. - human blood type AB.






30. The principal glucocorticoid secreted from teh adrenal cortex. This steroid hormone is released ruing stress - causing increased blood glucose levels and reducing inflammation. The latter effect has led to a clinical use of cortisol as an anti - infl






31. The blood vessels taht carry blood to and from cardiac muscle. The coronary arteries branch off teh aorta and carry oxygenated blood to the cardiac tissue. The coronary veins collect deoxygenated blood from teh cardiac tissue - merge to form teh coro






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






33. A four - carbon molecule that binds with the two - carbon acetyl unit of acetyl - CoA to form citric acid in the first step of the Krebs cycle.






34. 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






35. Toward the 5' end of an Rna transcript (the 5' end of the DNA coding strand). The promoter and start sites are upstream.






36. The fraction of teh end - diastolic volume ejected from the ventricles in a single contraction of teh heart. THe ejection fraction is normally around 60% of the end diastolic volume.






37. 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






38. A region within the nucleus where rRNA is transribed and ribosomes are partially assembled.






39. 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.






40. Connective tissue with large amounts of either collagen fibers (making them strong) or elastic fibers - or both. Dense tissues are typically strong (e.g. bone - cartilage - tendons - etc.)






41. A molecule formed by joining many monosaccharides together. POlysaccharides are typically energy- storage molecules (glycogen in animals - starch in plants) or structural molecules (cellulose in plants - chitin in exoskeletons).






42. 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.






43. A mechanism by which the stroke volume of the heart is increased by increasing the venous return of the heart (thus stretching the ventricular muscle).






44. The opening to the uterus The ervix is typically plugged with a sticky acidic mucus during non - fertile times (to form a barrier against the entry of pathogens) - however during ovulation the mucus becomes more watery and alkaline to facilitate sper






45. A projection of the cell body of a neuron that recieves a nerve impulse form a different neuron and send the impulse to the cell body. Neurons can have one or several dendrites!






46. 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






47. The middle (approximtely 40%) of the small intestine.






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






49. 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.






50. The movement of teh membrane potential of a cell away from rest potential in a more positive direction.