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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. A type of cell division (in diploid cells) that reduces the number of chromosomes by half. Meiosis usualy produces haploid gametes in organisms that undergo sexual reproduction. It consists of a single interphase (G1 - S - and G2) followed by two set






2. The second major node of the cardiac conduction system (after the SA node). The cardiac impulse is delayed slightly at teh AV node - allowing the ventricles to contract just after the atria contract.






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






4. 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).






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






6. Sperm production; occurs in human males on a daily basis from puberty until death. Spermatogenesis results in the production of four mature gametes (sperm) from a single precursor cell (spermatogonium). For maximum sperm viability - spermatogenesis r






7. A thick - gelatinous fluid found in the posterior segment of the eye (between the lens and the retina). The vireous humor is only produced during fetal development and helps maintain intraocular pressure (the pressure inside the eyeball).






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






9. A structure composed of two coils of DNA wrapped around an octet of histone proteins. The nucleosome is the primary form of packagin of eukaryotic DNA.






10. A strong connective tissue with varying degrees of flexibility. (1) Elastic cartilage is the most flexible - forming structures that reuqire support but also need to bend - such as the epiglottis and outer ear. (2) Hyaline cartilage is more rigid tha






11. A sensory receptor that responds to mechanical disturbances - such as shape changes (being squashed - bent - pulled - etc.). Mechanoreceptors include touch receptors in the skin - hair cells - in the ear - muscle spindles - and others.






12. Aromatic bases found in DNA and RNA that are derived from purine. They have a double rightn structure and include adenine and guanine.






13. The uptake of material into a cell - usually by invagination. See also 'phagocytosis' - pinocytosis - and receptor - mediated endocytosis..






14. The 3' end of a tRNA molecule that binds an amino acid. The nucleotide sequence at this end is CCA






15. Also called immunoblobins - the antibodies are protiens secreted by B- cells upon activation that bind in a highly specific manner to foreign proteins (such as those found of the surface of pathogens or transplanted tissues). The foreign proteins are






16. The constant inhibition provided to the heart by the vagus nerve. Vagal tone reduces the intrinsic firing rate of teh SA node from 120 beats/minute to around 80 beats/minute.






17. The valves in the heart that separate the ventricles from the arteries. The pulmonary semilunar valve separates the right ventricle from the pulmonary artery - and the aortic semilunar valve separates left ventricle from the aorta. These valves close






18. The fourth of meiosis I. Telophase I is identical to mitotic telophase - except that the number of chromosoms is now reduced by half. After this phase the cell is considered to be haploid. Note however - that the chromosomes are still replicated - an






19. The valvecontrolling release of bile and pancreatic juice into the bloodstream.






20. Also called negative feedback - the inhibition of an early step in a series of events by the product of a later step in the series. This has the effect of stopping the series of events when the products are plentiful and the series is unnecesseary. F






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






22. An enzyme that transcribes RNa. Prokaryotes have a single RNA pol - while eukaryotes have three; in eukaryotes - RNA pol I transcribes rRNA - RNA pol II transcribes mRNA - and RNA pol III transcribes tRNA.






23. A thin - watery fluid found in teh anterior segment of the eye (between the lens and the cornea). THe aqueous humor is constantly produced and drained - adn helps to bring nutrients to the lesn and corena - as well as to remove metabolic wastes






24. A long projection off the cell body of a neruon down which an action potential can be propagated.






25. Multiple sites of replication found on large - linear eukaryotic linear eukaryotie chromosomes.






26. A haploid cell resulting from the first meiotic division of oogenesi (not that the cytoplasmic division in this case is unequal - producing one large cell with almost all of they cytoplasm - the secondary oocyte - and one smaller cell with virtually






27. A smooth sustained muscle contraction - such as occurs in skeletal muscle when stimulation frequency is high enough (this is the normal type of contraction exhibited by skeletal muscle).






28. 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






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






30. One type of eukaryotic mRNA processing in which introns are removed from the primary transcript and exons are ligated together. SPlicing of transcripts can be different in different tissues.






31. The portion of the nephron where water reabsorption is regulated via antidiuretic hormone (ADH). Several nephrons empty into each collecting duct - and this is the final region through which urine must passon its way to the ureter.






32. The first phase of mitosis. During prophase the replicated chromosomes condense - the spindle is formed - and the nuclear envelope breaks apart into vessicles.






33. A specific DNA nucleotide sequence where transcriptional regulatory proteins can bind.






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






35. A set of veins that connect a capillary bed in the hypothalamus (the primary capillary plexus) with a capillary bed in the anterior pituitary gland (the secondary capillary bed). Releasing and inhibiting factors from the hypothalamus travel along the






36. All of the cell cycle except for mitosis. Interphase includes G1 - S phase - and G2.






37. Enzymes that degrade various macromolecules and that require an acidic pH to function properly. Acid hydrolases are found within the lysosomes of cells.






38. The portion of the nephron tubule after the loop of Henle - but before teh collecting duct. Selective reabsorption and secretion occur here - most notably regulated reabsorption of water and sodium.






39. The exchange of DNA between paired homologus chromosomes (tetrads) during prophase I of meiosis.






40. A point mutation in which a pyrimidine is substitued for a purine - or vice versa.






41. The primary muscle of inspiration. The diaphragm is stimulated to contract at regular intervals by the respiratory center in the medulla oblongata (via the phrenic nerve). Although it is made of skeletal muscle (and can therefore be voluntary control






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






43. A protein channel in a cell membrane that is specific for a particular ion - such as Na+ or K+. Ion channels may be constitutively open (leak channels) - or regulated (voltage - gated or ligand - gated).






44. A life cycle of animal viruses in which the mature viral particles bud from the host cell - acquiring an envelope (a coating of lipid bilayer) in the process.






45. Fat cell






46. A type of mutation in DNa where a single base is substituted for another.






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






48. An enzyme that cuts one or both strands of DNa to relieve the excess tension caused by the unwinding of the helix by helicase during replication.






49. The law of conservation of energy; the energy of the universe is constant - thus if the energy of a system increases - the energy of its surroundings must decrease - and vice versa.






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